STEREOSELECTIVE AND REGIOSELECTIVE PALLADIUM-CATALYZED HYDROARYLATIONAND HYDROVINYLATION OF FUNCTIONALIZED ALKYNES - A ROUTE TO SUBSTITUTED Z-2-CINNAMYL ESTERS, 3-CHROMEN-2-OLS, AND COUMARINS

The palladium-catalysed hydroarylation and hydrovinylation of methyl 3 -phenylpropynoate and iethoxy-1-(o-tetrahydropyranyloxy)phenyl-1-propy ne with aryl and vinyl halides or triflates in the presence of Pd(OAc) (2) and KOOCH has been studied. The reaction affords stereoselectively syn addition products. The regiochemical outcome appears to be contro lled by steric effects and the new carbon-carbon bond is generated pre ferentially on the carbon far from the aromatic ring ligated to the ac etylenic carbon. The reaction can be applied to the synthesis of 3-sub stituted-3-chromen-2-ols and 3-substituted coumarins.