Regioselective Synthesis of 2-(Aryloxythio)benzoates by the First (3+3) Cyclizations of 3-Aryloxythio-l-silyloxybuta-l,3-dienes with 3-Alkoxy-2-en-l-ones

摘要

Functionalized 2-(aryloxythio)benzoates were regio-selectively prepared by the first [3+3] cyclizations of 3-aryloxythio-l-trimethylsilyloxybuta-l,3-dienes with 3-alkoxy-2-en-l-ones.Diaryl sulfides are pharmacologically relevant compounds that occur in a number of natural products. Prominent examples include lissoclibadins, dibenzothiophenes, cyclic sulfides, varacins (lissoclinotoxins), and related natural products.1 Classic syntheses of diaryl sulfides include, for example, reactions of arenes with sulfur2 or sulfur dichloride,3 condensations of Grignard or organo-lithium reagents with chlorophenyl sulfides4 or base-mediated reactions of thiophenols with chloroarenes.5 The formation of pblysulfides and low regioselectivities are severe drawbacks of these methods. In contrast, transition-metal-catalyzed6 and metal-free7 C-S coupling reactions allow the synthesis of diaryl sulfides under relatively mild conditions. However, the scope of this approach is limited by the fact that reactions of sterically encumbered substrates are often difficult or not possible at all. In addition, the synthesis of the starting materials, substituted aryl halides or triflates, can be difficult and tedious.