A GENERAL SYNTHETIC ROUTE FOR 1-SUBSTITUTED 4-OXYGENATED BETA-CARBOLINES - (SYNTHETIC STUDIES ON INDOLES AND RELATED-COMPOUNDS .41.)

A new synthetic route for two naturally occurring 1-substituted 4-meth oxy-beta-carbolines (1b, c) is described. This synthetic route involve s elaboration of the ester groups in ethyl indole-2-carboxylate (4b) a nd its 1-benzyl derivative (4a), C-3-selective cyclization of the subs tituent at the C-2-position of the indole nucleus, and functionalizati on at the C-1-position of the beta-carboline nucleus by a modified Rei ssert-Henze reaction. The synthetic beta-carbolines (1b, c) should be key intermediates for the synthesis of their congeners, leading to a g eneral synthetic route of 1-substituted 4-oxygenated beta-carbolines. (C) 1997, Elsevier Science Ltd.