The preparation of thiophene-based azacryptand Mannich bases

Abstract

The preparation of cryptand-like structures, incorporating four thiophene rings, was undertaken. A variety of approaches were considered, but a stepwise process commencing from the readily available α,ω-bis(2-formyl-3-thienyloxy)alkanes of the type ArO-Z-OAr (where Ar = 2-formyl-3-thienyl and Z = heteroalkyl chain) yielded excellent results. A range of open chain and cyclic Mannich bases incorporating one or two macrorings was prepared via reduction of open chain and macrocyclic imines derived from the heteroalkyl-bridged bisaldehydes. Tosyl and acetyl derivatives of the reduced products, viz. the intermediate secondary amines were prepared; the latter exhibited diastereoisomerism.