The conformational analysis of saturated heterocycles. Part 87. Carbon-13 nuclear magnetic resonance studies of 1,3-diazacyclohexanes and some bi- and tri-cyclic analogues

Abstract

Variable temperature ¹³C n.m.r. studies elucidate the conformational equilibria and energetics of 1,3-dimethyl- and 1,2,3-trimethyl-1,3-diazacyclohexane, cis-1,3,4,7,8-pentamethyl-1,3,7-triazabicyclo[3.3.1]nonane, and 1,2,4,5,7,8-hexamethylperhydro-1,4,7,9b-tetra-azaphenalene. ¹³C N.m.r. shifts of the N-methyl carbon atoms in these compounds are correlated using the γ-gauche upfield shift criterion.