Palladium-catalyzed trans-selective alkynylation-alkylation tandem process for the synthesis of (E)-3-alkyl-1-trialkylsilyl-3-alken-1-ynes

The reaction of 1,1-dibromo- and 1,1-dichloro-1-alkenes with ClZnCCSiMe3 and 5% Pd(DPEphos)Cl2 followed by that with methylzincs and ethylzincs produces (E)-3-alkyl-1-trialkylsilyl-3-alken-1-ynes (≥98% E) in >90% yields.