Propylene derivatives lactones

The reaction of a a-phenylselanyl enolate derived from 15-pentadecanolide and fSj-propylene oxide furnished a 1 1 mixture of lactones [50] (Scheme 41). The butyrolactone, resulting from a partial trans lactonization, led to (+)-Squa-mostanal-A in 55 % yield after selenoxide syn elimination and PDC oxidation of the hydroxy group. 

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