title: Ab Initio and DFT Conformational Studies of Propanal, 2-Butanone, and Analogous Imines and Enamines.
abstract: The potential energy surfaces (PES) of 2-butanone, 2-butanimine, 1-butenamine, propanal, and propanimine have been explored with ab initio and DFT calculations at the RHF/6-311G**, MP2/6-311G**, and B3LYP/6-311G** levels of theory. In agreement with previous experimental and computational results, the PES provides two minima for each of the above molecules with the exception of 2-butanone, which clearly shows three distinct minima. Factors influencing the conformational preferences are also elaborated. Our calculations suggest that for 2-butanone and propanal, the steric and the bond dipole interactions are primarily responsible for the conformational preferences of these compounds. Additional charge-charge interactions might also play an important role in determining the imine conformations. For enamines, however, steric interactions play a critical role, with bond dipole interactions exerting some influence. Our results also suggest that for imine formation from butanone and/or propanal, the imine is the predominant product, not the enamine, which is consistent with experimental observations. Therefore, these calculations should provide a better understanding of the ketone/aldehyde to imine and enamine transformations. This transformation may introduce an important imine moiety for the analogues of trans-N-methyl-4-(1-naphthylvinyl)pyridine (NVP), a choline acetyltransferase (ChAT) inhibitor.
authors.affiliation: Center for Drug Design, Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, Computational Center for Molecular Structure and Design, Department of Chemistry, University of Georgia, Athens, Georgia 30602, and Laboratory for Molecular Modeling, Division of Medicinal Chemistry and Natural Products, School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599.
authors.forename: Haizhen
authors.initials: H
authors.lastname: Zhong
authors.affiliation: Center for Drug Design, Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, Computational Center for Molecular Structure and Design, Department of Chemistry, University of Georgia, Athens, Georgia 30602, and Laboratory for Molecular Modeling, Division of Medicinal Chemistry and Natural Products, School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599.
authors.forename: Eugene L
authors.initials: EL
authors.lastname: Stewart
authors.affiliation: Center for Drug Design, Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, Computational Center for Molecular Structure and Design, Department of Chemistry, University of Georgia, Athens, Georgia 30602, and Laboratory for Molecular Modeling, Division of Medicinal Chemistry and Natural Products, School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599.
authors.forename: Maria
authors.initials: M
authors.lastname: Kontoyianni
authors.affiliation: Center for Drug Design, Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, Computational Center for Molecular Structure and Design, Department of Chemistry, University of Georgia, Athens, Georgia 30602, and Laboratory for Molecular Modeling, Division of Medicinal Chemistry and Natural Products, School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599.
authors.forename: J Phillip
authors.initials: JP
authors.lastname: Bowen