Enynes, Negishi cross-coupling reaction

Dienes and l -enynes. Negishi et al have extended the synthesis of 1,3-enynes by palladium-catalyzed cross-coupling of alkynylzinc chlorides with an alkenyl halide (8, 472) to a similar stcrcospccific synthesis of 1,5-dienes or 1,5-enynes by coupling an alkenyl halide with a homoallyl- or homopropargylzinc chloride. An example is the synthesis of the 1,5-cnync I (equation 1). This reaction... 

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