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Abraham RJ, Filippi M, Petrillo G, Piaggio P, Vladiskovic C, Sancassan F. A theoretical and NMR lanthanide-induced shift (LIS) investigation of the conformations of lactams. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2017; 55:1059-1072. [PMID: 28783883 DOI: 10.1002/mrc.4643] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 08/01/2017] [Accepted: 08/01/2017] [Indexed: 06/07/2023]
Abstract
Molecular mechanics (MM) with MMFF94 and MMX force fields and ab initio (RHF/6-31G*,RHF/6-311G**, and B3LYP/6-311G**) calculations are used with lanthanide-induced shift (LIS) to investigate the conformations of N-methyl-2-pyrrolidone 1, N-methyl-2-piperidone 2, ε-caprolactam 3, γ-valerolactam (1,5-dimethyl-2-pyrrolidone) 4, 2-azetidinone 5, 4-methyl azetidinone 6, 4-phenyl azetidinone 7, and N-methyl-4-phenyl azetidinone 8. The Yb(fod)3 paramagnetic induced shifts of all the 1 H and 13 C nuclei are measured and the corresponding diamagnetic complexation shifts obtained by the addition of Lu(fod)3 . The complexation model (two-, three-, or four-site) used depends on the relative rates of the processes involved. The amide inversion is the same order as that of the 5- and 6-membered lactam rings and much faster than the lanthanide complexation and the inversion of the 7-membered ring. Both MM and ab initio calculations give an envelope conformation for 1 with C-4 out of the ring plane in agreement with the LIS analysis. For the piperidone ring of 2, the half-chair is calculated as the most stable form. The LIS analysis confirms this but cannot exclude a small amount (<2%) of the boat conformation. For 3, the LIS analysis gives a minimum for 90:10% chair to boat conformation, and 4 exists in two envelope conformations with the C5 -Me ps-eq and ps-ax in an eq/ax ratio of 94:6%. In 2-azetidinone 5, the ab initio calculations gave both ring and nitrogen planar, but the MMFF94 calculations give a butterfly ring and pyramidal nitrogen. The LIS analysis for 5 gave good agreement (Rcryst 0.46%) for the MMFF94 geometry with endo NH but the planar ab initio geometries worse agreement (Rcryst = 1.1%). For 4-methyl-2-azetidinone 6, the MMFF94 geometry gave good agreement (Rcryst 0.96%) with two butterfly conformations with axial and equatorial methyl groups in 1:1 ratio. All the planar geometries gave worse agreement (Rcryst >1.5%). In 4-phenyl azetidinone 7, the MMFF94 geometry with 60% of the axial conformer gave Rcryst 1.2% but the other geometries Rcryst >1.5%. In contrast the N-methyl-4-phenyl-2-azetidinone 8 gave good agreement for all the geometries. The butterfly conformation gave Rcryst 1.1% for 80% of the axial conformer and the planar geometries Rcryst 0.98%. The LIS results confirm the ab initio and MM optimised geometries, but the conformer energies at times differ from the calculated values. They also differ considerably from the corresponding values for the lactones studied previously, and possible reasons for this are discussed.
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Affiliation(s)
- Raymond J Abraham
- Department of Chemistry, The University of Liverpool, P. O. Box 147, Liverpool, L69 7ZD, UK
| | - Marco Filippi
- Dipartimento di Chimica e Chimica Industriale, Via Dodecaneso 31, I-16146, Genoa, Italy
| | - Giovanni Petrillo
- Dipartimento di Chimica e Chimica Industriale, Via Dodecaneso 31, I-16146, Genoa, Italy
| | - Paola Piaggio
- Dipartimento di Chimica e Chimica Industriale, Via Dodecaneso 31, I-16146, Genoa, Italy
| | - Chiara Vladiskovic
- Dipartimento di Chimica e Chimica Industriale, Via Dodecaneso 31, I-16146, Genoa, Italy
| | - Fernando Sancassan
- Dipartimento di Chimica e Chimica Industriale, Via Dodecaneso 31, I-16146, Genoa, Italy
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Zabalov MV, Tiger RP. Specificities of application of the supermolecule method to the calculation of reaction mechanisms in a protonodonor medium. Ethylene carbonate aminolysis in methanol. Theor Chem Acc 2017. [DOI: 10.1007/s00214-017-2124-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Xia X, Zhang C, Xue Y, Kim CK, Yan G. DFT Study and Monte Carlo Simulation on the Aminolysis of XC(O)OCH3 (X = NH2, H, and CF3) with Monomeric and Dimeric Ammonias. J Chem Theory Comput 2008; 4:1643-53. [DOI: 10.1021/ct800099a] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xuefei Xia
- College of Chemistry, Key Laboratory of Green Chemistry and Technology in Ministry of Education, Sichuan University, Chengdu 610064, P. R. China, State Key Laboratory of Biotherapy, Sichuan University, Chengdu 610041, P. R. China, and Department of Chemistry, Inha University, Inchon 402-751, Korea
| | - Chenghua Zhang
- College of Chemistry, Key Laboratory of Green Chemistry and Technology in Ministry of Education, Sichuan University, Chengdu 610064, P. R. China, State Key Laboratory of Biotherapy, Sichuan University, Chengdu 610041, P. R. China, and Department of Chemistry, Inha University, Inchon 402-751, Korea
| | - Ying Xue
- College of Chemistry, Key Laboratory of Green Chemistry and Technology in Ministry of Education, Sichuan University, Chengdu 610064, P. R. China, State Key Laboratory of Biotherapy, Sichuan University, Chengdu 610041, P. R. China, and Department of Chemistry, Inha University, Inchon 402-751, Korea
| | - Chan Kyung Kim
- College of Chemistry, Key Laboratory of Green Chemistry and Technology in Ministry of Education, Sichuan University, Chengdu 610064, P. R. China, State Key Laboratory of Biotherapy, Sichuan University, Chengdu 610041, P. R. China, and Department of Chemistry, Inha University, Inchon 402-751, Korea
| | - Guosen Yan
- College of Chemistry, Key Laboratory of Green Chemistry and Technology in Ministry of Education, Sichuan University, Chengdu 610064, P. R. China, State Key Laboratory of Biotherapy, Sichuan University, Chengdu 610041, P. R. China, and Department of Chemistry, Inha University, Inchon 402-751, Korea
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Díaz N, Sordo TL, Suárez D, Méndez R, Martín-Villacorta J. Zn2+catalysed hydrolysis of β-lactams: experimental and theoretical studies on the influence of the β-lactam structure. NEW J CHEM 2004. [DOI: 10.1039/b306799h] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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