Issue 0, 1986

Photochemical conversion of 3-azido-2-vinylthiophenes into thienopyrroles and of 2-azidostyrenes into indoles. High migratory aptitude of sulphur substituents

Abstract

On photolysis in acetonitrile 3-azido-2-vinylthiophenes (8a–h) give thieno[3,2-b]pyrroles (10), (16), (18)–(20), (23), (24), (26) and 2-azidostyrenes (9ad) give indoles (11) and (22). A mechanism is proposed involving formation and 1,5-electrocyclisation of the corresponding nitrene, followed by sigmatropic shift of one or both of the 2-substituents (Y, Z) in the 2H-pyrrole thus formed (Scheme 3). Decomposition of the two series of azides thus provides a measure of the relative migratory aptitudes of these substituents which are found to decrease in the order RSO > RS > H > RSO2 > RCO > EtO2C. The sulphide, sulphoxide, and sulphone groups are thus remarkably mobile.

Article information

Article type
Paper

J. Chem. Soc., Perkin Trans. 1, 1986, 501-506

Photochemical conversion of 3-azido-2-vinylthiophenes into thienopyrroles and of 2-azidostyrenes into indoles. High migratory aptitude of sulphur substituents

R. S. Gairns, C. J. Moody and C. W. Rees, J. Chem. Soc., Perkin Trans. 1, 1986, 501 DOI: 10.1039/P19860000501

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