An efficient and specific cleavage of the endo-C(sp)-Si bond of silole rings was developed. The stable silole ring was effectively opened in an unexpected regioselectivity by using an AcOH/ROH system, in which the AcOH behaved as a catalyst and the ROH as a nucleophile. Depending on the nature of the substituents at the 2- and 5-positions of the silole ring, the cooperative effect of the AcOH/ROH system exclusively cleaved one of the two endo-C-Si bonds to afford silylbutadiene derivatives. © The Royal Society of Chemistry 2011.