Easy Preparation Method for 2-Thioxopyrrolidine Derivatives Including 3-Hydroxy-methylene-2-thioxopyrrolidine, an Antimicrobial Degradation Product of Radish Pungent Principle, via (E, Z)-4-Methoxy-3-butenyl Isothiocyanate

An easy preparation method was developed for 3-hydroxymethylene-2-thioxopyrrolidine (TPC), an antimicrobial degradation product of radish pungent principle. The key intermediate, 4- methoxy-3-butenyl-isothiocyanate (MBI), which was prepared from 3-cyanopropionaldehyde dimethyl acetal in 3 reaction steps, was easily converted to TPC in acidic (pH 3.0–4.0) aqueous media. In methanol or ethanol with a few drops of acetic acid, MBI afforded corresponding 3-(α,α-dialkoxy)methyl-2-thioxopyrrolidines as the major products.