Preparation and thermal ring-closure of β-aryl vinyl carbodi-imides: synthesis of isoquinoline derivatives

Abstract

Reaction of the iminophosphoranes (7)–(9), derived from α-azidocinnamates and tri-phenylphosphine, with aromatic isocyanates gives either 1-arylaminoisoquinoline-3-carboxylates (10)–(12) or the corresponding carbodi-imides (14)–(18) which by thermal treatment at 230 °C are converted into 1-(N-aryl-N-imidazolylamino)isoquinoline-3-carboxylates (19)–(20). The iminophosphoranes (7) and (8) also react with aroyl chlorides to give the oxazolone derivatives (23)–(26).