Dienyl sulfoxides enantiomerically pure

These normally occur in a regio- and stereoselective manner and provide a useful alternative to the well-known AIBN-catalyzed radical addition. Cochran et al. [194] demonstrated this clearly in the case of the addition of MejSnH to diphenylacetylene, the radical addition proceeding in a trans manner and the Pd-catalyzed reaction cis. Rossi et al. carried out additions of BugSnH to 1,3-diynes to give 2-stannyl-l-en-3-ynes [195] and to esters of substituted propynoic acids [196]. A basically similar reaction was reported by Sai et al. [197]. Paley et al. [198] obtained enantiomerically pure dienyl sulfoxides by first... 

The first report concerning the synthesis of enantiomerically pure dienyl sulfoxides was made by Hoffmann and coworkers [32], who made use of the Horner-Wittig reaction between an a-phosphoryl sulfoxide and acrolein to give the corresponding dienyl sulfoxides as a mixture of geometric isomers. Recently, there has been considerable interest in the synthesis of 1-sulfinyl and 2-sulfinyl-l,3-butadienes, as these types of substrates have considerable potential as diene components in asymmetric Diels-Alder cycloadditions. 

The synthesis of enantiomerically pure dienyl sulfoxides through palladium-catalysed coupling reactions has been reported [36,37]. An efficient Stille coupling process was used to synthesize both (lE E)- and (lZ,3 )-l-sulfinyl-l,3-butadienes through the use of stereodelined vinyl stannanes [36]. For example, coupling of the P-bromo-a,P-imsaturated sulfoxide (23) with vinylstannane (24) under palladiiun catalysis leads to the enantiomerically pure (l , 3 )-l-sulfinyl-l,3-butadiene (25) (Scheme 5.8) [36]. 

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