Dienyl sulphoxides, synthesis

Dienes, synthesis of 731, 953, 956 Dienoic acids, synthesis of 675 Dienones, synthesis of 780 Dienyl sulphoxides, synthesis of 279, 810, 959... 

Another application of this strategy is the construction of cyclic systems bearing 1,4-dissonant relationships. For example, the synthesis of the hasubanan alkaloid ring system 35. reported in 1972 by Evans [24], involves the Diels-Alder cycloaddition of a dienyl sulphoxide 32 with an endocyclic enamine 33, followed by a [2,3]-sigmatropic rearrangement of the resulting cycloadduct 34 (Scheme 5.21). 

A synthetic equivalent to the 4-formyl-/ra/j5,/ra 5-buta-l,3-dienyl anion has appeared in a synthesis of 5-desoxyleukotriene D. The anion of /ra/i5-penta-2,4-dienyl sulphoxide shows good a-selectivity in its reaction with an aldehyde. Double [3,2] sigmatropic rearrangement transfers the functional group to the end of the chain, ready for the unmasking of the aldehyde by Pummerer rearrangement and hydrolysis (Scheme 12). 

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