Indole esters as heterocyclic synthons. II. Preparation of 1,3-oxazino[5,6-b]indoles and 3-substituted-pyrano[3,2-b]indoles

A number of novel 1,3-oxazino[5,6-b]indoles and 2-oxo- or 4-oxopyrano[3,2-b]indoles containing #3-position substituents were prepared. Starting materials were 3-hydroxy-indole-2-carboxylic acid esters in which the #2-position ester function is converted to carboxamide, β-ketoester, or β-ketosulfone.