Palladium-catalyzed cross-coupling of cyclopropylmethyl N-tosylhydrazones with aromatic bromides: an easy access to multisubstituted 1,3-butadienes

Direct synthesis of 1,1-disubstitued 1,3-butadienes has been efficiently realized from the cross-coupling of cyclopropylmethyl N-tosylhydrazones with aromatic bromides by means of PdCl2(MeCN)2 as catalyst. 1,1,4-Trisubstitued 1,3-butadiene derivatives were obtained in up to 70% yields through a one-pot procedure catalyzed by Pd(OAc)2 in the presence of excessive amount of aromatic bromides. The present methodology provides an easy and efficient route to multisubstituted 1,3-butadienes.