Nitrones and Oxaziridines. XLV. Formation of Pyrrolo[1,2-a]indoles by Intramolecular Nitrone Cycloaddition

Abstract

The N-allylindole-2-carbaldehydes (5)-(8) and related methyl ketones (9)-(12) undergo reaction with N- methylhydroxylamine to give the cycloadducts (14)-(17) and (19)-(22), respectively. These adducts contain isoxazolidine rings fused to pyrrolo [1,2-a] indole systems. Corresponding cycloaddition of the N- propargylindole derivatives (24) and (25) could not be effected and the nitrone (26) was isolated. The adducts (14)-(17) underwent hydrogenolysis of the isoxazolidine N-O bond to give the amino alcohols (27)-(30), together with traces of the alcohols (31)-(34). X-Ray crystallographic data for the cycloadducts (15) and (16b) are presented.