The synthesis and Diels–Alder reactions of (E)- and (Z)-1-methoxy-3-(phenylsulfinyl)buta-1,3-dienes

Abstract

The mild and efficient generation of benzenesulfenic acid by the thermolysis of ethyl 2-ethoxycarbonyl-3-(phenylsulfinyl)butanoate 8 in refluxing dichloromethane, and its in situ trapping with (E)- and (Z)-1-methoxybut-2-en-3-yne to form (E)-1-methoxy-3-(phenylsulfinyl)buta-1,3-diene 10 and (Z)-1-methoxy-3-(phenylsulfinyl)buta-1,3-dienes 11 respectively proceeds in high yield. The lithium perchlorate catalysed Diels–Alder reaction of 10 with both symmetrical and unsymmetrical carbonyl activated dienophiles proceeds with complete regioselectivity and in some cases complete endo-selectivity.