Crystal and molecular structure of 5-methoxycarbonylmethylene-2-piperidino-Δ2-thiazolin-4-one

Abstract

The structure of the addition product formed by N-thiocarbamoylpiperidine and dimethyl acetylenedicarboxylate has been shown to be 5-methoxycarbonylmethylene-2-piperidino-Δ²-thiazolin-4-one by a single-crystal X-ray analysis. The crystals, of formula C₁₁H₁₄N₂O₃S, are monoclinic, space group P2₁/c, with Z= 4 in a unit cell of dimensions a= 10·25, b= 16·51, c= 7·85 Å, β= 114·9°. The structure was solved by the heavy-atom method and refined by least-squares calculations to R= 0·115 for 1597 independent reflexions. The elucidation of the structure has yielded further information about the mechanism and stereochemistry of bidentate nucleophilic additions to acetylenic esters.