作者:Shang-Shing P. Chou、Mao-Hsun Chao
DOI:10.1002/jccs.199600009
日期:1996.2
AbstractTreatment of 3‐phenylthio‐2‐sulfolene (1) with an equimolar proportion of butyllithium at −78 °C in THF followed by addition of an electrophile gave the 2‐substituted 3‐phenylthio‐2‐sulfolenes (2). The deprotonation was found to proceed only at the vinylic C‐2 position. Some of the 2‐sulfolenes 2 underwent desulfonylation upon heating with base. Of particular interest was the conversion of 3‐phenylthio‐2‐trimethylsilyl‐2‐sulfolene (2h) to its 3‐sulfolene isomer 6 by sequential addition of butyllithium and salicylic acid at low temperatures. The 3‐sulfolene 6 was desulfonylated by Kugelrohr distillation at 150° C under vacuum to give (Z)‐2‐phenylthio‐l‐trimethylsilyl‐1,3‐butadiene (8). The regiochemistry of the Diels Alder reaction of this highly reactive diene 8 was found to be controlled by the phenylthio group, and the stereochemistry is endo addition. Diene 8 was oxidized to its sulfone derivative 12 which also underwent a stereospecific Diels‐Alder reaction.