Die Synthese von 2H-Thiopyranen aus β-Thioxoaldehyden

D. Greif; M. Pulst; M. Weißenfels

doi:10.1055/s-1987-33432

Synthesis 1987; 1987(5): 456-460
DOI: 10.1055/s-1987-33432

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Die Synthese von 2H-Thiopyranen aus ß-Thioxoaldehyden

D. Greif^* , M. Pulst, M. Weißenfels

^*Sektion Chemie der Karl-Marx-Universität, DDR-7010 Leipzig, Talstraße 35, German Democratic Republic

Abstract

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The Synthesis of 2H-Thiopyranes from ß-Thioxoaldehydes [4+2]-Cycloaddition reactions between enaminothioketones and activated alkenes, which are described by Quiniou et al.,^1-4 usually require relatively harsh reaction conditions, and produce the title compounds only in moderate yields. Much better results can be achieved by a new synthesis of 3-acyl-2H-thiopyranes starting with dicyclohexylammonium salts of monothio-ß-dicarbonyl compounds and unsaturated aldehydes or ketones. The mechanism of this new reaction is characterized by Michael addition followed by an aldol reaction.

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