Dynamic stereochemistry of imines and derivatives: 15—Carbon‐13 NMR studies of aryl‐substituted imines and oxaziridines

Abstract

Abstract 13 C chemical shifts for several series of cis ‐ and trans ‐ N ‐alkylimines and oxaziridines bearing para ‐substituted C‐phenyl rings are reported and correlated with dual substituent parameters. The 13 CN and oxaziridine ring carbon shifts correlate primarily with the inductive/field parameters, σ 1 , whereas both resonance and inductive terms generally contribute about equally to the long‐range substituent effects on alkyl side‐chain chemical shifts. Correlations on diastereoisomeric imines show that the transmission of substituent effects can be significantly affected by the E – Z configuration. Aromatic carbon chemical shifts in imines are discussed in relation to the E – Z configuration and the conformation around the aryl—imino bond.