Alkynes, halo hydration

Rawal and Thadani [160] have taken advantage of alkynes as excellent insertion partners in Pd(II)-catalyzed allylations. Interestingly, the Pd(II) species present in the medium after alkyne insertion into allyl chlorides or bromides can serve for a sequential Wacker-Tsuji oxidation upon introduction of CuCl, oxygen, and water to the reaction medium to give y-halo /-fy-cnones 220 in good yields (Scheme 91). If phenylacetylene is used as an alkyne l-phenyl-pent-2-ene-l,4-dione can be isolated in 77% yield as the result of a subsequent oxidative hydration of the y-halo P,y-enone 220. 

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