title: Looking Inside the Intramolecular C-H∙∙∙O Hydrogen Bond in Lactams Derived from α-Methylbenzylamine.
abstract: Recently, strong evidence that supports the presence of an intramolecular C-H···O hydrogen bond in amides derived from the chiral auxiliary α-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 α-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-Hα···O interaction. NBO analysis revealed that rehybridization at C atom of the C-Hα bond (s-character at C is ~23%) and the subsequent bond polarization are the dominant effect over the orbital interaction energyn(O)→σ*C-Hα(E(2) < 2 kcal/mol), causing an important shortening of the C-Hα bond distance and an increment in the positive charge in the Hα atom.
authors.affiliation: Centro de Investigación de la Facultad de Ciencias Químicas, and Centro de Química de la Benemérita Universidad Autónoma de Puebla, 14 Sur Esq. San Claudio, San Manuel. C. P. 72570 Puebla, Mexico. mejia.cabildo@gmail.com.
authors.forename: Sandra
authors.initials: S
authors.lastname: Mejía
authors.affiliation: Centro de Investigación de la Facultad de Ciencias Químicas, and Centro de Química de la Benemérita Universidad Autónoma de Puebla, 14 Sur Esq. San Claudio, San Manuel. C. P. 72570 Puebla, Mexico. julio.hernandez@correo.buap.mx.
authors.forename: Julio M
authors.initials: JM
authors.lastname: Hernández-Pérez
authors.affiliation: Centro de Investigación de la Facultad de Ciencias Químicas, and Centro de Química de la Benemérita Universidad Autónoma de Puebla, 14 Sur Esq. San Claudio, San Manuel. C. P. 72570 Puebla, Mexico. jsandovalira@gmail.com.
authors.forename: Jacinto
authors.initials: J
authors.lastname: Sandoval-Lira
authors.affiliation: Centro de Investigación de la Facultad de Ciencias Químicas, and Centro de Química de la Benemérita Universidad Autónoma de Puebla, 14 Sur Esq. San Claudio, San Manuel. C. P. 72570 Puebla, Mexico. fernando.sartillo@correo.buap.mx.
authors.forename: Fernando
authors.initials: F
authors.lastname: Sartillo-Piscil
mesh_terms: D006860:Hydrogen Bonding; D007769:Lactams / Q000138:chemical synthesis* / Q000737:chemistry; D008956:Models, Chemical; D008958:Models, Molecular; D010627:Phenethylamines / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: D007769:Lactams; D010627:Phenethylamines; C033198:1-phenethylamine
keywords: C−H···O interaction; MP2; chiral lactams; α-methylbenzylamine