Propionic Acid → Methyl 5-(3-carbomethoxy-2-phenylthiazolidin-4-yl)-4-pentenoate

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Reaction Steps

A solution of 44.0 g. (0.1575 mol) of crude 4-(1-hydroxyprop-2-en-1yl)-3-carbomethoxy-2-phenylthiazolidine, 191.5 g. (1.570 mol) of trimethylorthoacetate and 100 ml. of a 20% solution of propionic acid in benzene in 2 L. of benzene was heated for 24 hours, at 92°-93° C. The vapors were condensed and collected in a Dean-stark moisture receiver. After cooling, the resulting yellow solution was washed with 100 ml. of a 2N solution of sodium carbonate, then 3 × 100 ml. of water. Drying with magnesium sulfate and evaporation in vacuo gave 50.0 g. (95% yield) of crude methyl 5-(3-carbomethoxy-2-phenylthiazolidin-4-yl)-4-pentenoate. Gas chromatographic analysis showed a purity of 65-70%. If pure starting material is used instead in the process, no detectable impurities were detected in the final product.

Provenance & Evidence