1H nuclear magnetic resonance study of high-pressure effects on cis–trans interconversion of N-methyl-lactams

Abstract

An increase in pressure has been found to provide a shift in the conformational equilibrium toward a higher s-cis population for 15-, 17-, and 20-membered-ring lactams, while a slight decrease in the s-cis population upon increase in pressure has been observed for an 11-membered-ring lactam. The results are interpreted in terms of the difference in the molecular shape and polarity of s-cis- and s-trans-isomers.