Carbon-carbon bond cleavage by means of transition metals has received considerable attentions,which provides new opportunities for the discovery of synthetically useful reactions that are otherwise difficult.Among the strategies for this proposed transformation,the-carbon elimination of the cyclopropylmethyl metal species is an appealing model on account of the high strain energy of cyclopropane.Although the addition of M-M or R-M intermediates to the double bond of methylenecyclopropanes(MCPs) has been established as a common route for the generation of these transient cyclopropyl carbinyl metals,the process is found to be highly dependent on the substitution pattern of MCPs,which forms isomeric products in some cases.In 2012,we reported the Pd-catalyzed cross-coupling of cyclopropyl N-tosylhydrazones with aryl halides,leading to various linear 1,1-disubstituted 1,3-butadiene products(scheme 1,a).1 The reaction provides a novel route toward cyclopropylmethyl palladium species with the Pd-carbene migratory insertion as the characteristic step.