New facile experimental procedures for the preparation of 2, 3, 4, 6-tetrasubstituted pyridines in a single synthetic step have been developed. Thus, an enamino ester and alkynone react by Michael addition–cyclodehydration in a heterocyclisation process that is catalysed by acetic acid, Amberlyst 15 ion exchange resin, zinc (II) bromide or ytterbium (III) triflate. The new one-step Brønsted or Lewis acid-catalysed Bohlmann–Rahtz reaction is a ...
