New synthetic methods using the TiCl < inf > 4 < /inf > -NR < inf > 3 < /inf > reagentsystem

Abstract

The TiCl4-NR3 reagent system is useful for carbon-carbon bond forming reactions such as the aldol and related condensation reactions, the diastereoselective coupling of phenyl acetic acid derivatives, the conversion of aryl alkyl ketimines and ketoximes to pyrroles, ketazines to dihydrodiazines, enamines to aromatic amines, N,N-dialkylanilines to the corresponding benzidine derivatives, trialkylamines to unsaturated aldehydes, diarylcyclobutanones, diarylcyclobutylamine derivatives via iminium ion intermediates and for the reductive coupling of aromatic aldehydes, aldimines and intramolecular reductive coupling of chiral diimine derivatives. In all cases, the organic products are obtained in moderate to good yields, in single-pot operations under ambient reaction conditions. Hence, these synthetic methods have considerable synthetic potential.