The conformational analysis of saturated heterocycles. Part 84. Conformational consequences of internal β-heteroatoms. Ring and nitrogen inversion in 3,5-dimethyl-1-oxa-3,5-diaza-, 5-methyl-1,3-dioxa-5-aza-, and 1,3,5-trimethyl-, -triethyl-, -tri-isopropyl-, and -tri-t-butyl-1,3,5-triaza-cyclohexanes

Abstract

Variable temperature proton and carbon-13 dynamic n.m.r. spectroscopy has been used to study the inversion barriers and preferred conformations of 3,5-dimethyl-1-oxa-3,5-diaza-, 5-methyl-1,3-dioxa-5-aza-, and 1,3,5-trimethyl-1,3,5-triaza-cyclohexane. The conformational consequences of consecutively replacing O with NMe in passing from 1,3,5-trioxacyclohexane to 1,3,5-trimethyl-1,3,5-triazacyclohexane are discussed. The observed effects of increasing size of alkyl substituent on the 1,3,5-triazacyclohexane system are also discussed.