The reaction of t-butylithium with chlorodiphenylvinylsilane at low temperatures in hexane gave a 52% yield of the two isomeric 1,1,3,4-tetraphenyl-2,4-dineopenty-1,3-disilacyclo butanes mixture, formed by a head-to-tail dimerization of 1,1-diphenyl-2-neopentylsilene intermediate. In the presence of the trapping agents such as trimethylmethoxysilane and anthracene, the expected trapped adducts, 1-methoxy-l,l-diphenyl-2-trimethylsilyl-4,4-dimethyl-1-silapentane and 2,2-diphenyl-3-neopentyl-(5,6 : 7,8)-dibenzo-2-silabicyclo-(2.2.2)-octane, were obtained in 74% and 46% yields, respectively. These products were separated and their stereochemistry were assigned on the basis of $^1H$- and $^{13}C$-NMR data.