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Craft CL, Lemler PM, Vaccaro PH. Optical Activity in Saturated Cyclic Amines: Untangling the Roles of Nitrogen-Inversion and Ring-Puckering Dynamics. J Phys Chem A 2021; 125:5562-5584. [PMID: 34142836 DOI: 10.1021/acs.jpca.1c03882] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The dispersive optical activity of two saturated cyclic amines, (R)-2-methylpyrrolidine (R-2MPY) and (S)-2-methylpiperidine (S-2MPI), has been interrogated under isolated and solvated conditions to elucidate the roles of large-amplitude motion associated with nitrogen-center inversion and ring-puckering dynamics. Experimental optical rotatory dispersion profiles were almost mirror images of one another and displayed parallel solvent dependencies. Quantum-chemical analyses built on density-functional and coupled-cluster methods revealed four low-lying conformers for each molecule, which are distinguished by axial/equatorial orientations of their amino hydrogens and methyl substituents. Chiroptical signatures predicted for these species were combined through an independent-conformer ansatz to simulate the ensemble-averaged response, with a polarizable continuum model (PCM) being used to treat implicit solute-solvent interactions. The intrinsic behavior observed for isolated (gaseous) R-2MPY and S-2MPI was reproduced best by merging coupled-cluster (CCSD) estimates of rotatory powers with thermal population fractions deduced from complete basis set (CBS-APNO) free-energy calculations. Although prior claims of sizable chiroptical contributions arising from helically twisted (chiral) heterocyclic frameworks could be discounted, less satisfactory agreement between experiment and theory was realized for solution phases. Response properties sustained modest isomer-dependent changes in the presence of PCM solvation, but the corresponding energy metrics showed systematic trends, whereby structures having larger electric-dipole moments were stabilized preferentially in media of high polarity. Despite the fact that R-2MPY conformations were predicted to undergo a progressive reordering of their relative energies across the six solvents of interest, S-2MPI was found to exhibit more pronounced solvent-induced perturbations at long wavelengths (viz., in regions far removed from electronic resonances). Experimental results are discussed in terms of the distinct ring-puckering mechanisms for R-2MPY and S-2MPI, which are expected to be dominated by hindered pseudorotation among envelope/twist motifs and semi-inversion between chairlike antipodes, respectively.
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Affiliation(s)
- Clayton L Craft
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, United States
| | - Paul M Lemler
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, United States
| | - Patrick H Vaccaro
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, United States
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Müller TE, Hultzsch KC, Yus M, Foubelo F, Tada M. Hydroamination: Direct Addition of Amines to Alkenes and Alkynes. Chem Rev 2008; 108:3795-892. [PMID: 18729420 DOI: 10.1021/cr0306788] [Citation(s) in RCA: 1644] [Impact Index Per Article: 102.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Thomas E. Müller
- CAT Catalytic Center, ITMC, RWTH Aachen, Worringerweg 1, 52074 Aachen, Germany, Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854-8087, Departamento de Química Orgánica, Universidad de Alicante, E-03080 Alicante, Spain, and Department of Chemistry, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kai C. Hultzsch
- CAT Catalytic Center, ITMC, RWTH Aachen, Worringerweg 1, 52074 Aachen, Germany, Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854-8087, Departamento de Química Orgánica, Universidad de Alicante, E-03080 Alicante, Spain, and Department of Chemistry, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Miguel Yus
- CAT Catalytic Center, ITMC, RWTH Aachen, Worringerweg 1, 52074 Aachen, Germany, Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854-8087, Departamento de Química Orgánica, Universidad de Alicante, E-03080 Alicante, Spain, and Department of Chemistry, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Francisco Foubelo
- CAT Catalytic Center, ITMC, RWTH Aachen, Worringerweg 1, 52074 Aachen, Germany, Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854-8087, Departamento de Química Orgánica, Universidad de Alicante, E-03080 Alicante, Spain, and Department of Chemistry, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Mizuki Tada
- CAT Catalytic Center, ITMC, RWTH Aachen, Worringerweg 1, 52074 Aachen, Germany, Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854-8087, Departamento de Química Orgánica, Universidad de Alicante, E-03080 Alicante, Spain, and Department of Chemistry, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Gribkov DV, Hultzsch KC, Hampel F. 3,3‘-Bis(trisarylsilyl)-Substituted Binaphtholate Rare Earth Metal Catalysts for Asymmetric Hydroamination. J Am Chem Soc 2006; 128:3748-59. [PMID: 16536549 DOI: 10.1021/ja058287t] [Citation(s) in RCA: 296] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chiral 3,3'-bis(trisarylsilyl)-substituted binaphtholate rare earth metal complexes (R)-[Ln{Binol-SiAr3}(o-C6H4CH2NMe2)(Me2NCH2Ph)] (Ln = Sc, Lu, Y; Binol-SiAr3 = 3,3'-bis(trisarylsilyl)-2,2'-dihydroxy-1,1'-binaphthyl; Ar = Ph (2-Ln), 3,5-xylyl (3-Ln)) and (R)-[La{Binol-Si(3,5-xylyl)3}{E(SiMe3)2}(THF)2] (E = CH (4a), N (4b)) are accessible via facile arene, alkane, and amine elimination. They are efficient catalysts for the asymmetric hydroamination/cyclization of aminoalkenes, giving TOF of up to 840 h(-1) at 25 degrees C for 2,2-diphenyl-pent-4-enylamine (5c) using (R)-2-Y. Enantioselectivities of up to 95% ee were achieved in the cyclization of 5c with (R)-2-Sc. The reactions show apparently zero-order rate dependence on substrate concentration and first-order rate dependence on catalyst concentration, but rates depend on total amine concentrations. Activation parameters for the cyclization of pent-4-enylamine using (R)-2-Y (deltaH(S)(double dagger) = 57.4(0.8) kJ mol(-1) and deltaS(S)(double dagger) = -102(3) J K(-1) mol(-1); deltaH(R)(double dagger) = 61.5(0.7) kJ mol(-1) and deltaS(R)(double dagger) = -103(3) J K(-1) mol(-1)) indicate a highly organized transition state. The binaphtholate catalysts were also applied to the kinetic resolution of chiral alpha-substituted aminoalkenes with resolution factors f of up to 19. The 2,5-disubstituted aminopentenes were formed in 7:1 to > or = 50:1 trans diastereoselectivity, depending on the size of the alpha-substituent of the aminoalkene. Rate studies with (S)-1-phenyl-pent-4-enylamine ((S)-15e) gave the activation parameters for the matching (deltaH(double dagger) = 52.2(2.8) kJ mol(-1), deltaS(double dagger) = -127(8) J K(-1) mol(-1) using (S)-2-Y) and mismatching (deltaH(double dagger) = 57.7(1.3) kJ mol(-1), deltaS(double dagger) = -126(4) J K(-1) mol(-1) using (R)-2-Y) substrate/catalyst combination. The absolute configuration of the Mosher amide of (2S)-2-methyl-4,4-diphenyl-pyrrolidine and (2R)-methyl-(5S)-phenyl-pyrrolidinium chloride, prepared from (S)-15e, were determined by crystallographic analysis. Catalyst (R)-4a showed activity in the anti-Markovnikov addition of n-propylamine to styrene.
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Affiliation(s)
- Denis V Gribkov
- Institut für Organische Chemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Henkestrasse 42, D-91054 Erlangen, Germany
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