A Synthesis of Allylboronates via the Palladium(0)-Catalyzed Cross-Coupling Reaction of

Abstract: The cross-coupling reaction of bis(pinacolato)diboron [(Me4C2O2)BB(O2C2Me4)] with allyl acetates regioselectively provided the pinacol esters of allylboronic acids in high yields. The reaction was efficiently catalyzed by Pd(dba)2 in DMSO at 50 ｡C. Allylboron compounds are useful reagents in organic synthesis, addition of which to the carbon-oxygen or the carbon-nitrogen double bond diastereoselectively provides homoallylic alcohols or amines via a chair-like six-membered cyclic transition state.1 A number of methods is available for the synthesis of allylboron compounds including the transmetalation of allyllithiums or allylmagnesiums to the boron,2 the coupling of 1-alkenyl halides with borylmethylzinc reagents,3 the reaction of halomethylboronates with vinyllithiums,4 the mono-hydroboration of 1,2- or 1,3-dienes,5 and the one-carbon homologation of 1-alkenylboronates.6 The reaction of boryl nucleophiles with allylic electrophiles is a convenient and alternative candidate; however, this protocol has been throughly limited due to the lack of suitable boron nucleophiles.7 We have recently reported the cross-coupling reaction of bis(pinacolato)diboron (1) with aryl halide