The Synthesis of Substituted 2-Aryl 4(3H)-Quinazolinones using Nahso3/Dma. Steric Effect upon the Cyclisation-Dehydrogenation Step

Abstract

A number of 2-aryl substituted 6-pyrrolidino-4(3H)-quinazolinones are reported. They were synthesised in four steps starting from commercially available 5-chloro-2-nitrobenzoic acid. The key cyclisation-dehydrogenation step between 2-amino-pyrrolidinobenzamide 5 and different benzaldehydes employs NaHSO3 as the dehydrogenating agent in hot DMA. This last reaction shows a strong dependence on the position of the substituent at the aromatic ring of the benzaldehyde used. Thus, the 2-substituted benzaldehydes, in contrast to 3- and 4-substituted compounds give a poor yield of desired products or a mixture.