Stereochemistry of seven-membered heterocycles. Communication 17. PMR spectra and conformation of 2-methyl-2-phenyl-1, 3-dioxa-5,6-benzocycloheptene and its isomeric 4-methyl derivatives

Abstract

1. 2-Methyl-2-phenyl-1,3-dioxa-5,6-benzocycloheptene and its isomeric 4-methyl-substituted derivatives exist in the twist conformation. 2. In the PMR of these compounds the benzyl protons and 4-methyl groups are coupled and the screening influence of the 2-phenyl substituent on the gauche-oriented methylene protons was revealed. © 1986 Plenum Publishing Corporation.