SYNTHESIS, SPECTRAL AND BIOLOGICAL STUDIES OF OXAZINONE AND PYRONOINDOLES

Abstract

Acetonyl indole-2-carboxylates (2a-n) have been synthesised by the condensation of indole-2-carboxylic acids (1a-n) with chloroacetone in aq. ethanolic K2CO3. These indoles (2a-f) on cyclodehydration PPE in dry chloroform afford 1-methyl-4-pyrono[3,4-b]indoles (3a-f). The indoles (2g-n) on treatment with POCl3 in dry benzene furnish 1-methyl-oxazin-4-one[3,4-a]indoles (4g-n) in moderate yields. 3-Carbethoxy-2,4-dimethyl-6-pyrono[3,2-e]indoles (6p-u) are prepared by the cyclodehydration of Nenitzescu products (5p-u) with ethyl acetoacetate using conc. H2SO4 at low temperature.