Vinyl sulfones intramolecular cycloadditions

Recent synthetic applications of the photochemical [2 + 2] cycloaddition of unsaturated sulfones have been noted. Musser and Fuchs84 have effected an intramolecular [2 + 2] addition of a 6-membered ring vinyl sulfone and a five-membered ring vinylogous ester in excellent yield, as part of a synthetic approach to the synthesis of the mould metabolite, cytochalasin C. The stereospecificity of the addition was only moderate, however, and later problems with this synthetic approach led to its abandonment. Williams and coworkers85 have used the facile [2 + 2] photoaddition of 73 and... 

Synthesis of Hesitine Diterpenoid Alkaloids. An efficient enantioselec-tive approach to the hesitine class of the C2o-diterpenoid alkaloids involves an intramolecular oxidopyridinium dipolar cycloaddition with a vinylic sulfone as the key transformation as depicted in Eq. 156.266 Once the sulfonyl group has played its role in the C-C bond formation, it is removed by a Na/Hg-promoted reductive desulfonylafion. 

Metz has developed a highly diastereoselective intramolecular Diels-Alder reaction of furans with vinyl sulfonates [22]. When hydroxyfuran 10 a was esterified with vinylsulfonic acid chloride, the intermediate sulfonate spontaneously underwent cycloaddition to give sultone 11a, Eq. 9. In the same manner, (-)-llb was obtained from (i )-10b which was derived from L-valine. 

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