Cycloadditions of 3H-indoles

Abstract

Treatment of 3H-indoles (indolenines) with diethyl oxaloacetate and diethyl oxalopropionate, respectively, yield the pyrrolidones (4) and (3) and with thiobenzoyl isocyanate the thiadiazine (16) is formed. The 1:2 product (8) is formed with dimethyl acetylenedicarboxylate whilst thiocyanates and alkyl isothiocyanates yield triazine derivatives (11). In contrast, and not in accord with literature precedence, aryl and acyl isothiocyanates produce the thiadiazine derivatives (14).