Ketene-S, N-acetals as Synthetic Intermediates for Heterocycles. New Synthesis of Multisubstituted Pyridine-2-thiones

HIROKI TAKAHATA; ENG-CHI WANG; TOMOKO NAKAJIMA; TAKAO YAMAZAKI

doi:10.1248/cpb.35.3139

HIROKI TAKAHATA, ENG-CHI WANG, TOMOKO NAKAJIMA, TAKAO YAMAZAKI

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Keywords: ketene-S, N-acetal, thioamide, pyridine-2-thione, α-methylthioenamine, enaminonitrile, bis-lithioenamine

JOURNAL FREE ACCESS

1987 Volume 35 Issue 8 Pages 3139-3145

DOI https://doi.org/10.1248/cpb.35.3139

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Abstract

Ketene-S, N-acetals reacted with isothiocyanates to give β-aminothiocarbonyl-α-methylthioen-amines, which were transformed into enaminonitriles by carbon-carbon bond formation with malononitriles. Treatment of the enaminonitriles with base afforded pyridine-2-thiones. In addition, bis-lithio-ketene-S, N-acetals, generated from the enaminonitriles and n-BuLi, reacted with alkyl halides to give 3-alkylpyridine-2-thiones.

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