Looking Inside the Intramolecular C-H???O Hydrogen Bond in Lactams Derived from ?-Methylbenzylamine.

ABSTRACT: Recently, strong evidence that supports the presence of an intramolecular C-H···O hydrogen bond in amides derived from the chiral auxiliary ?-methylbenzylamine was disclosed. Due to the high importance of this chiral auxiliary in asymmetric synthesis, the inadvertent presence of this C-H···O interaction may lead to new interpretations upon stereochemical models in which this chiral auxiliary is present. Therefore, a series of lactams containing the chiral auxiliary ?-methylbenzylamine (from three to eight-membered ring) were theoretically studied at the MP2/cc-pVDZ level of theory with the purpose of studying the origin and nature of the C-H?···O interaction. NBO analysis revealed that rehybridization at C atom of the C-H? bond (s-character at C is ~23%) and the subsequent bond polarization are the dominant effect over the orbital interaction energy n_(O)??*_C-H? (E(2) < 2 kcal/mol), causing an important shortening of the C-H? bond distance and an increment in the positive charge in the H? atom.

SUBMITTER: Mejia S 

PROVIDER: S-EPMC6155423 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature