John F. Beck
- Courses1
- Reviews1
- School: Lake Michigan College
- Campus: Bertrand Crossing
- Department: Chemistry
- Email address: Join to see
- Phone: Join to see
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Location:
1905 Foundation Dr
Niles, MI - 49120 - Dates at Lake Michigan College: April 2018 - April 2018
- Office Hours: Join to see
Biography
Lake Michigan College Bertrand Crossing - Chemistry
Chair, Natural Sciences Department at Lake Michigan College
John F.
Beck, PhD
Saint Joseph, Michigan
I help students achieve the america dream by giving them the tools they need to be successful.
• Instructed students enrolled in Introductory Chemistry, Fundamentals of General, Organic, and Biochemistry, and Organic Chemistry
• Experienced with instructing non-traditional students, including high school students
• Redesigned organic chemistry laboratory incorporating green chemistry into organic chemistry one and natural product synthesis into organic chemistry two
• Prepare syllabi, lecture notes and other class materials
• Responsible for preparing online course materials using Canvas, Online Web Learning, and Mastering Chemistry
• Supervised students in both research and teaching laboratories
• Prepared peer reviewed scientific manuscripts
• Knowledgeable in homogeneous catalyst design and screenings
• Solved numerous small molecule structures, using single crystal XRD
Experience
Lake Michigan College
Instructor
Instructed student enrolled in Introductory Chemistry, Fundamentals of General, Organic, and Biochemistry, and Organic Chemistry I & II
Designed and delivered instruction through traditional and hybrid formats.
Redesigned organic chemistry laboratory incorporating green chemistry into organic chemistry and natural product synthesis into organic chemistry lab
Prepare syllabi, lecture notes and other class materials
Experienced with instructing non-traditional students
Experienced with instructing dual enrolled students
Responsible for preparing online course materials using Canvas, and Mastering Chemistry
Current Committee Assignments
Non-Traditional Students Committee
Strategic Scheduling Committee
Early/Middle College Committee
Previous Committee Assignments
Niles Middle College CommitteeLake Michigan College
Lecturer
- Instructed student enrolled in Introductory Chemistry, Fundamentals of General, Organic, and Biochemistry, and Organic Chemistry Laboratory
- Partially redesigned organic chemistry laboratory incorporating green chemistry into organic chemistry one and natural product synthesis into organic chemistry two
- Prepare syllabi, lecture notes and other class materials
- Experienced with instructing non-traditional students, including high school students
- Responsible for preparing online course materials using Canvas, Online Web Learning, and Mastering Chemistry.Lake Michigan College
Chair, Natural Sciences Department
John worked at Lake Michigan College as a Chair, Natural Sciences Department
Education
Western Michigan University
Bachelor of Science (BS)
Chemistry
University of Toledo
Ph.D. in Chemistry
Organometallics
Publications
Palladium catalyzed intermolecular hydroamination of 1-substituted allenes: an atom-economical method for the synthesis of N-allylamines
RSC Advances
The palladium complex [(3IPtBu)Pd(allyl)]OTf previously displayed excellent catalytic activity for the hydroamination of 1,1-dimethylallene with anilines, selectively producing the branched substituted allylamine product (kinetic product) in high conversion. In the current report, the scope of this hydroamination reaction has been expanded to include both alkyl amines and anilines in combination with an array of seven alkyl and aryl allenes. For the majority of amines investigated, the hydroamination of 1,1-dimethylallene, cyclohexylallene, benzylallene, and select aryl allenes with alkyl amines gave the branched substituted allylamine product in nearly quantitative conversion at ambient temperature in less than 1 hour. In contrast, anilines displayed a more limited reaction scope and yielded the linear hydroamination product (thermodynamic product) with all allenes other than 1,1-dimethylallene. Both branched and linear products could be formed selectively in the hydroamination of p-fluorophenylallene with alkyl amines through careful control of [(3IPtBu)Pd(allyl)]OTf catalyst loading and reaction duration. Overall, the branched allylamines produced are useful synthetic intermediates due to their available unsaturated vinyl group, while the linear allylamine products are chemically similar to a class of known pharmaceuticals.
Palladium catalyzed intermolecular hydroamination of 1-substituted allenes: an atom-economical method for the synthesis of N-allylamines
RSC Advances
The palladium complex [(3IPtBu)Pd(allyl)]OTf previously displayed excellent catalytic activity for the hydroamination of 1,1-dimethylallene with anilines, selectively producing the branched substituted allylamine product (kinetic product) in high conversion. In the current report, the scope of this hydroamination reaction has been expanded to include both alkyl amines and anilines in combination with an array of seven alkyl and aryl allenes. For the majority of amines investigated, the hydroamination of 1,1-dimethylallene, cyclohexylallene, benzylallene, and select aryl allenes with alkyl amines gave the branched substituted allylamine product in nearly quantitative conversion at ambient temperature in less than 1 hour. In contrast, anilines displayed a more limited reaction scope and yielded the linear hydroamination product (thermodynamic product) with all allenes other than 1,1-dimethylallene. Both branched and linear products could be formed selectively in the hydroamination of p-fluorophenylallene with alkyl amines through careful control of [(3IPtBu)Pd(allyl)]OTf catalyst loading and reaction duration. Overall, the branched allylamines produced are useful synthetic intermediates due to their available unsaturated vinyl group, while the linear allylamine products are chemically similar to a class of known pharmaceuticals.
Structural Characterization of Novel ortho-Lithiated Imines
European Journal of Inorganic Chemistry
ortho-Metallated imines are commonly used as ligands for late transition metals. Unfortunately, not all metals, such as titanium, zirconium, and niobium, can undergo the necessary oxidative addition reactions to form the desired ortho-metallated complexes directly. Therefore, a synthetic methodology allowing easy access to this binding mode from simple early transition metal halides via an ortho-lithiated imine precursor is desirable. ortho-Lithiation of benzylamines and othersystems has been well studied; in contrast, that of imines is poorly developed. However, inclusion of a 3,4-methylenedioxy group on phenyl imines allows for straightforward lithiation and simple isolation of the ortho-lithiated imines. NMR spectroscopy and single-crystal X-ray diffraction allowed for the structural elucidation of the clustering in these lithium complexes. It has been determined that the nature of the imine nitrogen substituent has a profound effect on the clustering of the lithiated imines. Alkyl (Cy, tBu) substituents clustered in a tetrameric form, whereas aryl (2,6-R2C6H3; R = Me, Et, iPr) substituents formed dimers that exhibited long-range ordering in the solid state as coordination polymers. The introduction of coordinating solvent, such as dimethoxyethane and diethyl ether, changed the long-range order of the coordination polymer and in some cases, forced the formation of discrete dimeric lithium complexes. Lithium NMR spectroscopy indicates that in solution the coordination polymer breaks up to form discrete dimers. These complexes also display a pronounced decrease in the ring bond angle of the aromatic carbon atom directly attached to the lithium atom, which indicates an increase in the p-character of the carbon–lithium bond.
Palladium catalyzed intermolecular hydroamination of 1-substituted allenes: an atom-economical method for the synthesis of N-allylamines
RSC Advances
The palladium complex [(3IPtBu)Pd(allyl)]OTf previously displayed excellent catalytic activity for the hydroamination of 1,1-dimethylallene with anilines, selectively producing the branched substituted allylamine product (kinetic product) in high conversion. In the current report, the scope of this hydroamination reaction has been expanded to include both alkyl amines and anilines in combination with an array of seven alkyl and aryl allenes. For the majority of amines investigated, the hydroamination of 1,1-dimethylallene, cyclohexylallene, benzylallene, and select aryl allenes with alkyl amines gave the branched substituted allylamine product in nearly quantitative conversion at ambient temperature in less than 1 hour. In contrast, anilines displayed a more limited reaction scope and yielded the linear hydroamination product (thermodynamic product) with all allenes other than 1,1-dimethylallene. Both branched and linear products could be formed selectively in the hydroamination of p-fluorophenylallene with alkyl amines through careful control of [(3IPtBu)Pd(allyl)]OTf catalyst loading and reaction duration. Overall, the branched allylamines produced are useful synthetic intermediates due to their available unsaturated vinyl group, while the linear allylamine products are chemically similar to a class of known pharmaceuticals.
Structural Characterization of Novel ortho-Lithiated Imines
European Journal of Inorganic Chemistry
ortho-Metallated imines are commonly used as ligands for late transition metals. Unfortunately, not all metals, such as titanium, zirconium, and niobium, can undergo the necessary oxidative addition reactions to form the desired ortho-metallated complexes directly. Therefore, a synthetic methodology allowing easy access to this binding mode from simple early transition metal halides via an ortho-lithiated imine precursor is desirable. ortho-Lithiation of benzylamines and othersystems has been well studied; in contrast, that of imines is poorly developed. However, inclusion of a 3,4-methylenedioxy group on phenyl imines allows for straightforward lithiation and simple isolation of the ortho-lithiated imines. NMR spectroscopy and single-crystal X-ray diffraction allowed for the structural elucidation of the clustering in these lithium complexes. It has been determined that the nature of the imine nitrogen substituent has a profound effect on the clustering of the lithiated imines. Alkyl (Cy, tBu) substituents clustered in a tetrameric form, whereas aryl (2,6-R2C6H3; R = Me, Et, iPr) substituents formed dimers that exhibited long-range ordering in the solid state as coordination polymers. The introduction of coordinating solvent, such as dimethoxyethane and diethyl ether, changed the long-range order of the coordination polymer and in some cases, forced the formation of discrete dimeric lithium complexes. Lithium NMR spectroscopy indicates that in solution the coordination polymer breaks up to form discrete dimers. These complexes also display a pronounced decrease in the ring bond angle of the aromatic carbon atom directly attached to the lithium atom, which indicates an increase in the p-character of the carbon–lithium bond.
Isolation and Characterization of Main Group and Late Transition Metal Complexes using orthoMetallated Imine Ligands
Dalton Transactions
Several late transition metal and main grouporthometallated imine complexes were synthesized by utilizing ortholithiated imine precursors. Magnesium, aluminum, zinc, copper(I), and tin(IV) complexes were isolated and characterized. Subsequent reactions with electrophiles such as Ph2PCl, MeI and I2 yielded several functionalized products, including a new iminophosphine ligand and its corresponding copper(I) complex. The coordination modes of the orthometallated imine ligands, as well as the structures of the metal complexes, were studied in the solid state using small molecule X-ray diffraction when possible.
Palladium catalyzed intermolecular hydroamination of 1-substituted allenes: an atom-economical method for the synthesis of N-allylamines
RSC Advances
The palladium complex [(3IPtBu)Pd(allyl)]OTf previously displayed excellent catalytic activity for the hydroamination of 1,1-dimethylallene with anilines, selectively producing the branched substituted allylamine product (kinetic product) in high conversion. In the current report, the scope of this hydroamination reaction has been expanded to include both alkyl amines and anilines in combination with an array of seven alkyl and aryl allenes. For the majority of amines investigated, the hydroamination of 1,1-dimethylallene, cyclohexylallene, benzylallene, and select aryl allenes with alkyl amines gave the branched substituted allylamine product in nearly quantitative conversion at ambient temperature in less than 1 hour. In contrast, anilines displayed a more limited reaction scope and yielded the linear hydroamination product (thermodynamic product) with all allenes other than 1,1-dimethylallene. Both branched and linear products could be formed selectively in the hydroamination of p-fluorophenylallene with alkyl amines through careful control of [(3IPtBu)Pd(allyl)]OTf catalyst loading and reaction duration. Overall, the branched allylamines produced are useful synthetic intermediates due to their available unsaturated vinyl group, while the linear allylamine products are chemically similar to a class of known pharmaceuticals.
Structural Characterization of Novel ortho-Lithiated Imines
European Journal of Inorganic Chemistry
ortho-Metallated imines are commonly used as ligands for late transition metals. Unfortunately, not all metals, such as titanium, zirconium, and niobium, can undergo the necessary oxidative addition reactions to form the desired ortho-metallated complexes directly. Therefore, a synthetic methodology allowing easy access to this binding mode from simple early transition metal halides via an ortho-lithiated imine precursor is desirable. ortho-Lithiation of benzylamines and othersystems has been well studied; in contrast, that of imines is poorly developed. However, inclusion of a 3,4-methylenedioxy group on phenyl imines allows for straightforward lithiation and simple isolation of the ortho-lithiated imines. NMR spectroscopy and single-crystal X-ray diffraction allowed for the structural elucidation of the clustering in these lithium complexes. It has been determined that the nature of the imine nitrogen substituent has a profound effect on the clustering of the lithiated imines. Alkyl (Cy, tBu) substituents clustered in a tetrameric form, whereas aryl (2,6-R2C6H3; R = Me, Et, iPr) substituents formed dimers that exhibited long-range ordering in the solid state as coordination polymers. The introduction of coordinating solvent, such as dimethoxyethane and diethyl ether, changed the long-range order of the coordination polymer and in some cases, forced the formation of discrete dimeric lithium complexes. Lithium NMR spectroscopy indicates that in solution the coordination polymer breaks up to form discrete dimers. These complexes also display a pronounced decrease in the ring bond angle of the aromatic carbon atom directly attached to the lithium atom, which indicates an increase in the p-character of the carbon–lithium bond.
Isolation and Characterization of Main Group and Late Transition Metal Complexes using orthoMetallated Imine Ligands
Dalton Transactions
Several late transition metal and main grouporthometallated imine complexes were synthesized by utilizing ortholithiated imine precursors. Magnesium, aluminum, zinc, copper(I), and tin(IV) complexes were isolated and characterized. Subsequent reactions with electrophiles such as Ph2PCl, MeI and I2 yielded several functionalized products, including a new iminophosphine ligand and its corresponding copper(I) complex. The coordination modes of the orthometallated imine ligands, as well as the structures of the metal complexes, were studied in the solid state using small molecule X-ray diffraction when possible.
Palladium(II) 3-iminophosphine (3IP) complexes: Active precatalysts for the intermolecular hydroamination of 1,2-dienes (allenes) and 1,3-dienes with aliphatic amines under mild conditions
Journal of Organometallic Chemistry
The synthesis of alicyclic 3-iminophosphine ligands is extended to include a new framework incorporating a cyclohexenyl backbone with an N-aryl imino functionality (3IPAr). Accordingly, a series of palladium(II) complexes employing this new ligand have been synthesized and utilized in the intermolecular hydroamination of 3-methyl-1,2-butadiene (1,1-dimethylallene) and 2,3-dimethyl-1,3-butadiene with secondary amines. The complex [(3IPAr)Pd(allyl)]OTf displays excellent catalytic activity in these reactions, selectively producing allylic amine products in high conversion under mild conditions, with an improved rate relative to that observed for our previously reported catalysts. Further, the reactivity trends for the (3IP)Pd triflate systems prove to be complimentary to other known late transition metal based catalytic systems.
Palladium catalyzed intermolecular hydroamination of 1-substituted allenes: an atom-economical method for the synthesis of N-allylamines
RSC Advances
The palladium complex [(3IPtBu)Pd(allyl)]OTf previously displayed excellent catalytic activity for the hydroamination of 1,1-dimethylallene with anilines, selectively producing the branched substituted allylamine product (kinetic product) in high conversion. In the current report, the scope of this hydroamination reaction has been expanded to include both alkyl amines and anilines in combination with an array of seven alkyl and aryl allenes. For the majority of amines investigated, the hydroamination of 1,1-dimethylallene, cyclohexylallene, benzylallene, and select aryl allenes with alkyl amines gave the branched substituted allylamine product in nearly quantitative conversion at ambient temperature in less than 1 hour. In contrast, anilines displayed a more limited reaction scope and yielded the linear hydroamination product (thermodynamic product) with all allenes other than 1,1-dimethylallene. Both branched and linear products could be formed selectively in the hydroamination of p-fluorophenylallene with alkyl amines through careful control of [(3IPtBu)Pd(allyl)]OTf catalyst loading and reaction duration. Overall, the branched allylamines produced are useful synthetic intermediates due to their available unsaturated vinyl group, while the linear allylamine products are chemically similar to a class of known pharmaceuticals.
Structural Characterization of Novel ortho-Lithiated Imines
European Journal of Inorganic Chemistry
ortho-Metallated imines are commonly used as ligands for late transition metals. Unfortunately, not all metals, such as titanium, zirconium, and niobium, can undergo the necessary oxidative addition reactions to form the desired ortho-metallated complexes directly. Therefore, a synthetic methodology allowing easy access to this binding mode from simple early transition metal halides via an ortho-lithiated imine precursor is desirable. ortho-Lithiation of benzylamines and othersystems has been well studied; in contrast, that of imines is poorly developed. However, inclusion of a 3,4-methylenedioxy group on phenyl imines allows for straightforward lithiation and simple isolation of the ortho-lithiated imines. NMR spectroscopy and single-crystal X-ray diffraction allowed for the structural elucidation of the clustering in these lithium complexes. It has been determined that the nature of the imine nitrogen substituent has a profound effect on the clustering of the lithiated imines. Alkyl (Cy, tBu) substituents clustered in a tetrameric form, whereas aryl (2,6-R2C6H3; R = Me, Et, iPr) substituents formed dimers that exhibited long-range ordering in the solid state as coordination polymers. The introduction of coordinating solvent, such as dimethoxyethane and diethyl ether, changed the long-range order of the coordination polymer and in some cases, forced the formation of discrete dimeric lithium complexes. Lithium NMR spectroscopy indicates that in solution the coordination polymer breaks up to form discrete dimers. These complexes also display a pronounced decrease in the ring bond angle of the aromatic carbon atom directly attached to the lithium atom, which indicates an increase in the p-character of the carbon–lithium bond.
Isolation and Characterization of Main Group and Late Transition Metal Complexes using orthoMetallated Imine Ligands
Dalton Transactions
Several late transition metal and main grouporthometallated imine complexes were synthesized by utilizing ortholithiated imine precursors. Magnesium, aluminum, zinc, copper(I), and tin(IV) complexes were isolated and characterized. Subsequent reactions with electrophiles such as Ph2PCl, MeI and I2 yielded several functionalized products, including a new iminophosphine ligand and its corresponding copper(I) complex. The coordination modes of the orthometallated imine ligands, as well as the structures of the metal complexes, were studied in the solid state using small molecule X-ray diffraction when possible.
Palladium(II) 3-iminophosphine (3IP) complexes: Active precatalysts for the intermolecular hydroamination of 1,2-dienes (allenes) and 1,3-dienes with aliphatic amines under mild conditions
Journal of Organometallic Chemistry
The synthesis of alicyclic 3-iminophosphine ligands is extended to include a new framework incorporating a cyclohexenyl backbone with an N-aryl imino functionality (3IPAr). Accordingly, a series of palladium(II) complexes employing this new ligand have been synthesized and utilized in the intermolecular hydroamination of 3-methyl-1,2-butadiene (1,1-dimethylallene) and 2,3-dimethyl-1,3-butadiene with secondary amines. The complex [(3IPAr)Pd(allyl)]OTf displays excellent catalytic activity in these reactions, selectively producing allylic amine products in high conversion under mild conditions, with an improved rate relative to that observed for our previously reported catalysts. Further, the reactivity trends for the (3IP)Pd triflate systems prove to be complimentary to other known late transition metal based catalytic systems.
Titanium imido complexes utilizing orthometallated derivatized acetophenone and piperonal imine ligands: synthesis, isolation, and characterization
Dalton Transactions
A series of five ortho-lithiated imines (Li-Ln; n = 1–5) was synthesized via the reaction of an aryl or alkyl acetophenone imine with n-butyllithium. The ortho-lithiated imines were subsequently reacted with Ti(NR)Cl2py3 (R = C(CH3)3, 2,6-Me2C6H3, 2,6-Et2C6H3, or 2,6-iPr2C6H3), yielding complexes of the form (Ln)2Ti(NR). Several of the resulting complexes [(L1)2Ti(NC(CH3)3), 1a; (L3)2Ti(N-2,6-Me2C6H3), 3b; and (L5)2Ti(NC(CH3)3), 5a] were structurally characterized using small molecule X-ray diffraction. The C2 symmetric complexes produced in these reactions displayed a distorted square pyramidal geometry. In each complex the titanium center was located above the square plane of the two coordinated bidentate ligands and the chelating C[similar]N ligands were folded away from the metal center. When a less sterically demanding alkylimine was used (L4), the resulting complex was isolated as an equilibrium mixture of cis and trans isomers of the empirical formula (L4)2Ti(NC(CH3)3)py (cis/trans4a).
Palladium catalyzed intermolecular hydroamination of 1-substituted allenes: an atom-economical method for the synthesis of N-allylamines
RSC Advances
The palladium complex [(3IPtBu)Pd(allyl)]OTf previously displayed excellent catalytic activity for the hydroamination of 1,1-dimethylallene with anilines, selectively producing the branched substituted allylamine product (kinetic product) in high conversion. In the current report, the scope of this hydroamination reaction has been expanded to include both alkyl amines and anilines in combination with an array of seven alkyl and aryl allenes. For the majority of amines investigated, the hydroamination of 1,1-dimethylallene, cyclohexylallene, benzylallene, and select aryl allenes with alkyl amines gave the branched substituted allylamine product in nearly quantitative conversion at ambient temperature in less than 1 hour. In contrast, anilines displayed a more limited reaction scope and yielded the linear hydroamination product (thermodynamic product) with all allenes other than 1,1-dimethylallene. Both branched and linear products could be formed selectively in the hydroamination of p-fluorophenylallene with alkyl amines through careful control of [(3IPtBu)Pd(allyl)]OTf catalyst loading and reaction duration. Overall, the branched allylamines produced are useful synthetic intermediates due to their available unsaturated vinyl group, while the linear allylamine products are chemically similar to a class of known pharmaceuticals.
Structural Characterization of Novel ortho-Lithiated Imines
European Journal of Inorganic Chemistry
ortho-Metallated imines are commonly used as ligands for late transition metals. Unfortunately, not all metals, such as titanium, zirconium, and niobium, can undergo the necessary oxidative addition reactions to form the desired ortho-metallated complexes directly. Therefore, a synthetic methodology allowing easy access to this binding mode from simple early transition metal halides via an ortho-lithiated imine precursor is desirable. ortho-Lithiation of benzylamines and othersystems has been well studied; in contrast, that of imines is poorly developed. However, inclusion of a 3,4-methylenedioxy group on phenyl imines allows for straightforward lithiation and simple isolation of the ortho-lithiated imines. NMR spectroscopy and single-crystal X-ray diffraction allowed for the structural elucidation of the clustering in these lithium complexes. It has been determined that the nature of the imine nitrogen substituent has a profound effect on the clustering of the lithiated imines. Alkyl (Cy, tBu) substituents clustered in a tetrameric form, whereas aryl (2,6-R2C6H3; R = Me, Et, iPr) substituents formed dimers that exhibited long-range ordering in the solid state as coordination polymers. The introduction of coordinating solvent, such as dimethoxyethane and diethyl ether, changed the long-range order of the coordination polymer and in some cases, forced the formation of discrete dimeric lithium complexes. Lithium NMR spectroscopy indicates that in solution the coordination polymer breaks up to form discrete dimers. These complexes also display a pronounced decrease in the ring bond angle of the aromatic carbon atom directly attached to the lithium atom, which indicates an increase in the p-character of the carbon–lithium bond.
Isolation and Characterization of Main Group and Late Transition Metal Complexes using orthoMetallated Imine Ligands
Dalton Transactions
Several late transition metal and main grouporthometallated imine complexes were synthesized by utilizing ortholithiated imine precursors. Magnesium, aluminum, zinc, copper(I), and tin(IV) complexes were isolated and characterized. Subsequent reactions with electrophiles such as Ph2PCl, MeI and I2 yielded several functionalized products, including a new iminophosphine ligand and its corresponding copper(I) complex. The coordination modes of the orthometallated imine ligands, as well as the structures of the metal complexes, were studied in the solid state using small molecule X-ray diffraction when possible.
Palladium(II) 3-iminophosphine (3IP) complexes: Active precatalysts for the intermolecular hydroamination of 1,2-dienes (allenes) and 1,3-dienes with aliphatic amines under mild conditions
Journal of Organometallic Chemistry
The synthesis of alicyclic 3-iminophosphine ligands is extended to include a new framework incorporating a cyclohexenyl backbone with an N-aryl imino functionality (3IPAr). Accordingly, a series of palladium(II) complexes employing this new ligand have been synthesized and utilized in the intermolecular hydroamination of 3-methyl-1,2-butadiene (1,1-dimethylallene) and 2,3-dimethyl-1,3-butadiene with secondary amines. The complex [(3IPAr)Pd(allyl)]OTf displays excellent catalytic activity in these reactions, selectively producing allylic amine products in high conversion under mild conditions, with an improved rate relative to that observed for our previously reported catalysts. Further, the reactivity trends for the (3IP)Pd triflate systems prove to be complimentary to other known late transition metal based catalytic systems.
Titanium imido complexes utilizing orthometallated derivatized acetophenone and piperonal imine ligands: synthesis, isolation, and characterization
Dalton Transactions
A series of five ortho-lithiated imines (Li-Ln; n = 1–5) was synthesized via the reaction of an aryl or alkyl acetophenone imine with n-butyllithium. The ortho-lithiated imines were subsequently reacted with Ti(NR)Cl2py3 (R = C(CH3)3, 2,6-Me2C6H3, 2,6-Et2C6H3, or 2,6-iPr2C6H3), yielding complexes of the form (Ln)2Ti(NR). Several of the resulting complexes [(L1)2Ti(NC(CH3)3), 1a; (L3)2Ti(N-2,6-Me2C6H3), 3b; and (L5)2Ti(NC(CH3)3), 5a] were structurally characterized using small molecule X-ray diffraction. The C2 symmetric complexes produced in these reactions displayed a distorted square pyramidal geometry. In each complex the titanium center was located above the square plane of the two coordinated bidentate ligands and the chelating C[similar]N ligands were folded away from the metal center. When a less sterically demanding alkylimine was used (L4), the resulting complex was isolated as an equilibrium mixture of cis and trans isomers of the empirical formula (L4)2Ti(NC(CH3)3)py (cis/trans4a).
Hydroamination of 1,1-Dimethylallene with Primary Aryl Amines Under Mild Conditions: An Atom-Economical Route to N-(1,1-Dimethyl-2-Propenyl)-Anilines
RSC Advances
The synthesis of alicyclic 3-iminophosphine ligands was extended to include a new framework incorporating a cyclopentenyl backbone with a di-tert-butyl phosphine functionality (3IPtBu). The palladium complex [(3IPtBu)Pd(allyl)]OTf displayed excellent catalytic activity in the 100% atom-efficient hydroamination of 3-methyl-1,2-butadiene (1,1-dimethylallene) with primary aryl amines (anilines), selectively producing the branched allylic amine products (kinetic products) in high conversion at ambient temperature for non-halogenated substrates. Hydroamination using halogenated anilines was successful at 70 °C, providing moderate yields, with the formation of little or no linear product (thermodynamic product). Additionally, a subsequent aromatic amino Claisen rearrangement of selected allylic amine products, employing catalytic triflic acid, proved to be an effective atom-economical method for the production of ortho-allylic anilines in a high yielding two-step, one-pot synthesis.
Palladium catalyzed intermolecular hydroamination of 1-substituted allenes: an atom-economical method for the synthesis of N-allylamines
RSC Advances
The palladium complex [(3IPtBu)Pd(allyl)]OTf previously displayed excellent catalytic activity for the hydroamination of 1,1-dimethylallene with anilines, selectively producing the branched substituted allylamine product (kinetic product) in high conversion. In the current report, the scope of this hydroamination reaction has been expanded to include both alkyl amines and anilines in combination with an array of seven alkyl and aryl allenes. For the majority of amines investigated, the hydroamination of 1,1-dimethylallene, cyclohexylallene, benzylallene, and select aryl allenes with alkyl amines gave the branched substituted allylamine product in nearly quantitative conversion at ambient temperature in less than 1 hour. In contrast, anilines displayed a more limited reaction scope and yielded the linear hydroamination product (thermodynamic product) with all allenes other than 1,1-dimethylallene. Both branched and linear products could be formed selectively in the hydroamination of p-fluorophenylallene with alkyl amines through careful control of [(3IPtBu)Pd(allyl)]OTf catalyst loading and reaction duration. Overall, the branched allylamines produced are useful synthetic intermediates due to their available unsaturated vinyl group, while the linear allylamine products are chemically similar to a class of known pharmaceuticals.
Structural Characterization of Novel ortho-Lithiated Imines
European Journal of Inorganic Chemistry
ortho-Metallated imines are commonly used as ligands for late transition metals. Unfortunately, not all metals, such as titanium, zirconium, and niobium, can undergo the necessary oxidative addition reactions to form the desired ortho-metallated complexes directly. Therefore, a synthetic methodology allowing easy access to this binding mode from simple early transition metal halides via an ortho-lithiated imine precursor is desirable. ortho-Lithiation of benzylamines and othersystems has been well studied; in contrast, that of imines is poorly developed. However, inclusion of a 3,4-methylenedioxy group on phenyl imines allows for straightforward lithiation and simple isolation of the ortho-lithiated imines. NMR spectroscopy and single-crystal X-ray diffraction allowed for the structural elucidation of the clustering in these lithium complexes. It has been determined that the nature of the imine nitrogen substituent has a profound effect on the clustering of the lithiated imines. Alkyl (Cy, tBu) substituents clustered in a tetrameric form, whereas aryl (2,6-R2C6H3; R = Me, Et, iPr) substituents formed dimers that exhibited long-range ordering in the solid state as coordination polymers. The introduction of coordinating solvent, such as dimethoxyethane and diethyl ether, changed the long-range order of the coordination polymer and in some cases, forced the formation of discrete dimeric lithium complexes. Lithium NMR spectroscopy indicates that in solution the coordination polymer breaks up to form discrete dimers. These complexes also display a pronounced decrease in the ring bond angle of the aromatic carbon atom directly attached to the lithium atom, which indicates an increase in the p-character of the carbon–lithium bond.
Isolation and Characterization of Main Group and Late Transition Metal Complexes using orthoMetallated Imine Ligands
Dalton Transactions
Several late transition metal and main grouporthometallated imine complexes were synthesized by utilizing ortholithiated imine precursors. Magnesium, aluminum, zinc, copper(I), and tin(IV) complexes were isolated and characterized. Subsequent reactions with electrophiles such as Ph2PCl, MeI and I2 yielded several functionalized products, including a new iminophosphine ligand and its corresponding copper(I) complex. The coordination modes of the orthometallated imine ligands, as well as the structures of the metal complexes, were studied in the solid state using small molecule X-ray diffraction when possible.
Palladium(II) 3-iminophosphine (3IP) complexes: Active precatalysts for the intermolecular hydroamination of 1,2-dienes (allenes) and 1,3-dienes with aliphatic amines under mild conditions
Journal of Organometallic Chemistry
The synthesis of alicyclic 3-iminophosphine ligands is extended to include a new framework incorporating a cyclohexenyl backbone with an N-aryl imino functionality (3IPAr). Accordingly, a series of palladium(II) complexes employing this new ligand have been synthesized and utilized in the intermolecular hydroamination of 3-methyl-1,2-butadiene (1,1-dimethylallene) and 2,3-dimethyl-1,3-butadiene with secondary amines. The complex [(3IPAr)Pd(allyl)]OTf displays excellent catalytic activity in these reactions, selectively producing allylic amine products in high conversion under mild conditions, with an improved rate relative to that observed for our previously reported catalysts. Further, the reactivity trends for the (3IP)Pd triflate systems prove to be complimentary to other known late transition metal based catalytic systems.
Titanium imido complexes utilizing orthometallated derivatized acetophenone and piperonal imine ligands: synthesis, isolation, and characterization
Dalton Transactions
A series of five ortho-lithiated imines (Li-Ln; n = 1–5) was synthesized via the reaction of an aryl or alkyl acetophenone imine with n-butyllithium. The ortho-lithiated imines were subsequently reacted with Ti(NR)Cl2py3 (R = C(CH3)3, 2,6-Me2C6H3, 2,6-Et2C6H3, or 2,6-iPr2C6H3), yielding complexes of the form (Ln)2Ti(NR). Several of the resulting complexes [(L1)2Ti(NC(CH3)3), 1a; (L3)2Ti(N-2,6-Me2C6H3), 3b; and (L5)2Ti(NC(CH3)3), 5a] were structurally characterized using small molecule X-ray diffraction. The C2 symmetric complexes produced in these reactions displayed a distorted square pyramidal geometry. In each complex the titanium center was located above the square plane of the two coordinated bidentate ligands and the chelating C[similar]N ligands were folded away from the metal center. When a less sterically demanding alkylimine was used (L4), the resulting complex was isolated as an equilibrium mixture of cis and trans isomers of the empirical formula (L4)2Ti(NC(CH3)3)py (cis/trans4a).
Hydroamination of 1,1-Dimethylallene with Primary Aryl Amines Under Mild Conditions: An Atom-Economical Route to N-(1,1-Dimethyl-2-Propenyl)-Anilines
RSC Advances
The synthesis of alicyclic 3-iminophosphine ligands was extended to include a new framework incorporating a cyclopentenyl backbone with a di-tert-butyl phosphine functionality (3IPtBu). The palladium complex [(3IPtBu)Pd(allyl)]OTf displayed excellent catalytic activity in the 100% atom-efficient hydroamination of 3-methyl-1,2-butadiene (1,1-dimethylallene) with primary aryl amines (anilines), selectively producing the branched allylic amine products (kinetic products) in high conversion at ambient temperature for non-halogenated substrates. Hydroamination using halogenated anilines was successful at 70 °C, providing moderate yields, with the formation of little or no linear product (thermodynamic product). Additionally, a subsequent aromatic amino Claisen rearrangement of selected allylic amine products, employing catalytic triflic acid, proved to be an effective atom-economical method for the production of ortho-allylic anilines in a high yielding two-step, one-pot synthesis.
Mono-anionic acetophenone imine ligands: synthesis, ortho-lithiation and first examples of group (V) metal complexes
Dalton Transactions
A series of niobium and tantalum imido complexes with mono-anionic ortho-metallated acetophenone imine ligands have been prepared and characterized using NMR spectroscopy, mass spectrometry and elemental analysis. These low symmetry complexes are produced with only one or two structural isomers in all cases and display interesting correlations between the steric bulk of the ligands employed and the isomers formed. Crystal structures of several new niobium and tantalum complexes are presented as confirmation of the connectivity in these structural isomers.
Palladium catalyzed intermolecular hydroamination of 1-substituted allenes: an atom-economical method for the synthesis of N-allylamines
RSC Advances
The palladium complex [(3IPtBu)Pd(allyl)]OTf previously displayed excellent catalytic activity for the hydroamination of 1,1-dimethylallene with anilines, selectively producing the branched substituted allylamine product (kinetic product) in high conversion. In the current report, the scope of this hydroamination reaction has been expanded to include both alkyl amines and anilines in combination with an array of seven alkyl and aryl allenes. For the majority of amines investigated, the hydroamination of 1,1-dimethylallene, cyclohexylallene, benzylallene, and select aryl allenes with alkyl amines gave the branched substituted allylamine product in nearly quantitative conversion at ambient temperature in less than 1 hour. In contrast, anilines displayed a more limited reaction scope and yielded the linear hydroamination product (thermodynamic product) with all allenes other than 1,1-dimethylallene. Both branched and linear products could be formed selectively in the hydroamination of p-fluorophenylallene with alkyl amines through careful control of [(3IPtBu)Pd(allyl)]OTf catalyst loading and reaction duration. Overall, the branched allylamines produced are useful synthetic intermediates due to their available unsaturated vinyl group, while the linear allylamine products are chemically similar to a class of known pharmaceuticals.
Structural Characterization of Novel ortho-Lithiated Imines
European Journal of Inorganic Chemistry
ortho-Metallated imines are commonly used as ligands for late transition metals. Unfortunately, not all metals, such as titanium, zirconium, and niobium, can undergo the necessary oxidative addition reactions to form the desired ortho-metallated complexes directly. Therefore, a synthetic methodology allowing easy access to this binding mode from simple early transition metal halides via an ortho-lithiated imine precursor is desirable. ortho-Lithiation of benzylamines and othersystems has been well studied; in contrast, that of imines is poorly developed. However, inclusion of a 3,4-methylenedioxy group on phenyl imines allows for straightforward lithiation and simple isolation of the ortho-lithiated imines. NMR spectroscopy and single-crystal X-ray diffraction allowed for the structural elucidation of the clustering in these lithium complexes. It has been determined that the nature of the imine nitrogen substituent has a profound effect on the clustering of the lithiated imines. Alkyl (Cy, tBu) substituents clustered in a tetrameric form, whereas aryl (2,6-R2C6H3; R = Me, Et, iPr) substituents formed dimers that exhibited long-range ordering in the solid state as coordination polymers. The introduction of coordinating solvent, such as dimethoxyethane and diethyl ether, changed the long-range order of the coordination polymer and in some cases, forced the formation of discrete dimeric lithium complexes. Lithium NMR spectroscopy indicates that in solution the coordination polymer breaks up to form discrete dimers. These complexes also display a pronounced decrease in the ring bond angle of the aromatic carbon atom directly attached to the lithium atom, which indicates an increase in the p-character of the carbon–lithium bond.
Isolation and Characterization of Main Group and Late Transition Metal Complexes using orthoMetallated Imine Ligands
Dalton Transactions
Several late transition metal and main grouporthometallated imine complexes were synthesized by utilizing ortholithiated imine precursors. Magnesium, aluminum, zinc, copper(I), and tin(IV) complexes were isolated and characterized. Subsequent reactions with electrophiles such as Ph2PCl, MeI and I2 yielded several functionalized products, including a new iminophosphine ligand and its corresponding copper(I) complex. The coordination modes of the orthometallated imine ligands, as well as the structures of the metal complexes, were studied in the solid state using small molecule X-ray diffraction when possible.
Palladium(II) 3-iminophosphine (3IP) complexes: Active precatalysts for the intermolecular hydroamination of 1,2-dienes (allenes) and 1,3-dienes with aliphatic amines under mild conditions
Journal of Organometallic Chemistry
The synthesis of alicyclic 3-iminophosphine ligands is extended to include a new framework incorporating a cyclohexenyl backbone with an N-aryl imino functionality (3IPAr). Accordingly, a series of palladium(II) complexes employing this new ligand have been synthesized and utilized in the intermolecular hydroamination of 3-methyl-1,2-butadiene (1,1-dimethylallene) and 2,3-dimethyl-1,3-butadiene with secondary amines. The complex [(3IPAr)Pd(allyl)]OTf displays excellent catalytic activity in these reactions, selectively producing allylic amine products in high conversion under mild conditions, with an improved rate relative to that observed for our previously reported catalysts. Further, the reactivity trends for the (3IP)Pd triflate systems prove to be complimentary to other known late transition metal based catalytic systems.
Titanium imido complexes utilizing orthometallated derivatized acetophenone and piperonal imine ligands: synthesis, isolation, and characterization
Dalton Transactions
A series of five ortho-lithiated imines (Li-Ln; n = 1–5) was synthesized via the reaction of an aryl or alkyl acetophenone imine with n-butyllithium. The ortho-lithiated imines were subsequently reacted with Ti(NR)Cl2py3 (R = C(CH3)3, 2,6-Me2C6H3, 2,6-Et2C6H3, or 2,6-iPr2C6H3), yielding complexes of the form (Ln)2Ti(NR). Several of the resulting complexes [(L1)2Ti(NC(CH3)3), 1a; (L3)2Ti(N-2,6-Me2C6H3), 3b; and (L5)2Ti(NC(CH3)3), 5a] were structurally characterized using small molecule X-ray diffraction. The C2 symmetric complexes produced in these reactions displayed a distorted square pyramidal geometry. In each complex the titanium center was located above the square plane of the two coordinated bidentate ligands and the chelating C[similar]N ligands were folded away from the metal center. When a less sterically demanding alkylimine was used (L4), the resulting complex was isolated as an equilibrium mixture of cis and trans isomers of the empirical formula (L4)2Ti(NC(CH3)3)py (cis/trans4a).
Hydroamination of 1,1-Dimethylallene with Primary Aryl Amines Under Mild Conditions: An Atom-Economical Route to N-(1,1-Dimethyl-2-Propenyl)-Anilines
RSC Advances
The synthesis of alicyclic 3-iminophosphine ligands was extended to include a new framework incorporating a cyclopentenyl backbone with a di-tert-butyl phosphine functionality (3IPtBu). The palladium complex [(3IPtBu)Pd(allyl)]OTf displayed excellent catalytic activity in the 100% atom-efficient hydroamination of 3-methyl-1,2-butadiene (1,1-dimethylallene) with primary aryl amines (anilines), selectively producing the branched allylic amine products (kinetic products) in high conversion at ambient temperature for non-halogenated substrates. Hydroamination using halogenated anilines was successful at 70 °C, providing moderate yields, with the formation of little or no linear product (thermodynamic product). Additionally, a subsequent aromatic amino Claisen rearrangement of selected allylic amine products, employing catalytic triflic acid, proved to be an effective atom-economical method for the production of ortho-allylic anilines in a high yielding two-step, one-pot synthesis.
Mono-anionic acetophenone imine ligands: synthesis, ortho-lithiation and first examples of group (V) metal complexes
Dalton Transactions
A series of niobium and tantalum imido complexes with mono-anionic ortho-metallated acetophenone imine ligands have been prepared and characterized using NMR spectroscopy, mass spectrometry and elemental analysis. These low symmetry complexes are produced with only one or two structural isomers in all cases and display interesting correlations between the steric bulk of the ligands employed and the isomers formed. Crystal structures of several new niobium and tantalum complexes are presented as confirmation of the connectivity in these structural isomers.
How resonance assists hydrogen bonding interactions: an energy decomposition analysis
Journal of Computational Chemistry
Block-localized wave function (BLW) method, which is a variant of the ab initio valence bond (VB) theory, was employed to explore the nature of resonance-assisted hydrogen bonds (RAHBs) and to investigate the mechanism of synergistic interplay between π delocalization and hydrogen-bonding interactions. We examined the dimers of formic acid, formamide, 4-pyrimidinone, 2-pyridinone, 2-hydroxpyridine, and 2-hydroxycyclopenta-2,4-dien-1-one. In addition, we studied the interactions in β-diketone enols with a simplified model, namely the hydrogen bonds of 3-hydroxypropenal with both ethenol and formaldehyde. The intermolecular interaction energies, either with or without the involvement of π resonance, were decomposed into the Hitler-London energy (ΔEHL), polarization energy (ΔEpol), charge transfer energy (ΔECT), and electron correlation energy (ΔEcor) terms. This allows for the examination of the character of hydrogen bonds and the impact of π conjugation on hydrogen bonding interactions. Although it has been proposed that resonance-assisted hydrogen bonds are accompanied with an increasing of covalency character, our analyses showed that the enhanced interactions mostly originate from the classical dipole–dipole (i.e., electrostatic) attraction, as resonance redistributes the electron density and increases the dipole moments in monomers. The covalency of hydrogen bonds, however, changes very little. This disputes the belief that RAHB is primarily covalent in nature. Accordingly, we recommend the term “resonance-assisted binding (RAB)” instead of “resonance-assisted hydrogen bonding (RHAB)” to highlight the electrostatic, which is a long-range effect, rather than the electron transfer nature of the enhanced stabilization in RAHBs.
Possible Matching Profiles
The following profiles may or may not be the same professor:
- Thomas John Beckett (-10% Match)
Adjunct Faculty
Valdosta Technical College - Valdosta Technical College - John Beckem II (-10% Match)
Associate Professor
SUNY Empire State College - Su Empire State College
