High yield access to silylene RSiCl (R = PhC(NtBu)2) and its reactivity toward alkyne: synthesis of stable disilacyclobutene.

Two new approaches for synthesizing RSiCl, (R = PhC(NtBu)(2)) are reported by the reaction of RSiHCl(2) with bis-trimethyl silyl lithium amide and N-heterocyclic carbene respectively. In the former method silylene is produced in 90% yield. The silylene was treated with biphenyl alkyne to afford the disilacyclobutene system. This is a rare example of two five-coordinate silicon centers arranged adjacent to each other in a four-membered ring. Furthermore, we fluorinated the four-membered ring by trimethyltin fluoride to obtain the fluoro substituted disilacyclobutene.