Synthese und Eigenschaften von 2-Methoxycarbonylmethylen- und 2- (Formyl-methoxycarbonylmethylen)-2H-Thiopyran-3-carbonsäureme-thylesterHerrn Professor Dr. Siegfried Hauptmann in Verbundenheit herzlichst zu seinem 60. Geburtstag

0021-8383

Chemistry ; Organic Chemistry

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Synthesis and Properties of Methyl-2-methoxycarbonylmethylene- and -2-(formyl- methoxycarbonylmethylene)-2H-thiopyran-3-carboxylatesDimethyl-2-chloro-propene-l,3-dicarboxylate is a easily available reactive C2-building block for the synthesis of 2H-thiopyran derivatives la  -  n in good yields via [C3S + C2]-cyclisation reactions using β-thioxoaldehydes and their derivatives as C3S-synthons. The structure of the stable red products with Z-configuration (side chain in position 2 of the ring) is elucidated by means of several analytical and spectroscopic methods including X-ray analysis of compounds 1h and lk.Treating of 1 with Vilsmeier reagent yields title compounds 2 with a remarkable less reactive formyl group at the exo-methylene group. There is obviously a shielding effect of the carboxylate groups.

3 Ill.

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