Yasuo Abe

Hydroquinone and Quinone Derivatives of the (Z)- and (E)-β-Thiocrotonates

Addition of ethyl thioacetoacetate to p-benzoquinone and 1,4-naphthoquinone gave satisfactory yields of the expected ethyl(Z)-β-(2,5-dihydroxyphenylthio)crotonate and ethyl(Z)-β-(1,4-dihydroxynaphthyl-2-thio)crotonate respectively. In the latter case, at higher temperatures the isomeric ethyl(E)-β-(1,4-dihydroxynaphthy 1-2-thio)crotonate was the major product. Oxidation of these compounds with chromic acid gave the corresponding Z-and E-isomeric quinone derivatives, but oxidation of the Z-isomer of the phenyl compound at higher temperatures gave the (E)-quinone derivative. All eight isomers in these two series have been isolated, characterized and identified by NMR assignment.