Sulfones, allyl dienyl synthesis

As far as polyenes are concerned, the Ramberg-Backlund reaction is an extremely powerful tool in putting the double bonds together. Herein just two examples are listed. Cao applied the Chan modification on a group of allylic dienylic sulfones and achieved the stereoselective synthesis of substituted all-tram-1,3,5,7-octatetraenes as exemplified by transformations 9899. 55 Polyene 101 was produced from sulfone 100 using the Chan modification as well.56... 

Allylic and dienyl sulfones have been prepared by conjugate addition to 1,3-dienes ". Phenylsulfonyhnercuration of conjugated dienes gives mercury adducts which can be treated with base to afford phenylsulfonyldienes. 2-(Phenylsulfonyl)-l,3-dienes can be stereo- and regioselectively functionalized via Michael addition of nucleophiles to give allylic sulfones. A key intermediate in the synthesis of a Monarch butterfly pheromone 4 was prepared by BackvaU and Juntunen by alkylation and subsequent palladium-catalyzed substitution of the allylic sulfone formed by Michael addition of dimethyl malonate to 2-(phenylsulfonyl)-l,3-butadiene (equation 10). 

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