Unusual cleavage of the enolsilane C-O bond: Transformation of 2-silyloxy-1,3-dienes into 1,3-dienyl-2-zirconium compounds and their cross-coupling reactions

Aryl enolsilanes and 2-silyloxy-1,3-dienes react with zirconocene to give a lkenylzirconium, and novel 1-methylene-2-propenylzirconium compounds which can be used as 2-dienylation reagents. Thus, one-pot coupling of 4-phenyl-1 ,3-butadienyl-2-zirconocene (2d) with a range of electrophiles including ar yl, alkynyl, allyl halides, bromine, iodine and a Michael acceptor occurs r egioselectively at the C-2 position in the presence of Pd or Cu catalysts.