ChemInform Abstract: Stereoselective Syntheses of (Z)‐(10‐Methoxy‐4H‐benzo(4,5)cyclohepta(1, 2‐b)thiophen‐4‐ylidene)acetic Acid.

Abstract

StereoselectiveSyntheses of (Z)-(10-Methoxy-4Hbenzo(4,5)cyclohepta(1, 2-b)thiophen-4-ylidene)acetic Acid.-The title compound (VIII) has been shown to exhibit antirheumatic activity, the corresponding E isomer is distinctly less active. Among the two stereoselective syntheses developed for the anti-inflammatory Z isomer the one outlined in the scheme is suitable as a basis for a technical preparation process. Starting with (I), the compound (III) is obtained selectively from a mixture with its diastereomer (by combining thermodynamic epimerization and solubility differences) and converted into (VI) using a novel thiophene anellation method. The sulfoxide (VII) is transformed into the target compound by a highly stereospecific "syn"-elimination. -(WALDVOGEL, E.; Helv. Chim. Acta 77 (1994) 3, 470-480; Chem. Verfahrens-Forsch. und-Entwickl., Sandoz AG, Switz.; DE)