Pyrrolo[2,3-d]pyrimidines. Synthesis from 4-pyrimidylhydrazones, a 2-bis(methylthio)methyleneaminopyrrole-3-carbonitrile, and a pyrrolo[2,3-d][1,3]thiazine-2(1H)-thione

Abstract

The synthesis of pyrrolo[2,3-d]pyrimidines and 5,6,7,8-tetrahydropyrimido[4,5-b]indoles by means of a thermally induced cyclisation of 4-pyrimidylhydrazones is shown to be of limited generality owing to the high reaction temperatures required, and to steric constraints on the [3,3] sigmatropic shift involved.

4,7-Diihydro-4-imino-5-phenylpyrrolo[2,3-d][1,3]thiazine-2(1H)-thione was conveniently prepared from 2-amino-4-phenylpyrrole-3-carbonitrile and proved to be a useful intermediate, both for the production of two series of 4-iminopyrrolo[2,3-d]pyrimidines, and for the synthesis of a 1H-pyrrolo[2,3-d]pyrimidine-2,4(3H,7H)-dithione and two 2-thioxo-4-ketones.