Triethylamine → 3-Indolizinecarboxylic acid, 2-(methylthio)-, ethyl ester

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Reaction Steps

A solution of 1-ethoxycarbonylmethylpyridinium bromide 5 (6.15 g, 25 mmol), 1,1-bis(methylsulphanyl)-2-nitroethylene (8.2 g, 50 mmol) and 25 g of triethylamine in 150 ml of ethanol was heated at reflux for 12 h. Following evaporation of the solvents and of the excess triethylamine, 150 ml of water were added to the residue, and the organic phase was extracted with petroleum ether (75 ml×3). The combined extracts were dried over anhydrous magnesium sulphate, filtered and then concentrated under vacuum. The residual oil was chromatographed on a neutral alumina column, with hexane as the eluting solvent, to give ethyl 2-(methylsulphanyl)-3-indolizinecarboxylate 9 (5.4 g).

Provenance & Evidence