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Issue 0, 1982
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Ring contractions of thiochroman-4-ones and thiochromen-4-ones

Abstract

3-Bromothiochroman-4-one and its S-oxide undergo ring contraction on heating, especially in the presence of sodium acetate, to give mixtures which include thioindigo (9) and the ethanediylidenethioindigo (10). Brominated 2,2-dimethylthiochroman-4-one reacts on silica gel to form thioindigo, thioindirubin, and the bis(benzothieno)pyran (17).

Bromination of thiochromanone gives a number of products, including 2,3-dibromothiochromen-4-one S-oxide which, on heating with sodium acetate in acetic acid, is converted efficiently into thioindigo. The mechanism of this reaction is investigated.

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Article type: Paper
DOI: 10.1039/P19820000395
J. Chem. Soc., Perkin Trans. 1, 1982, 395-402

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    Ring contractions of thiochroman-4-ones and thiochromen-4-ones

    N. E. MacKenzie and R. H. Thomson, J. Chem. Soc., Perkin Trans. 1, 1982, 395
    DOI: 10.1039/P19820000395

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