New cyclic and macrocyclic silaolefins via ring-closing metathesis of 1,1-bis(silyl)ethene-tethered dienes

Dialkenyl-substituted 1,1-bis(silyl)ethenes of the general formulae (CH2double bond; length as m-dashCH(CH2)nMe2Si)2Cdouble bond; length as m-dashCH2 and (CH2double bond; length as m-dashCH(CH2)nOMe2Si)2Cdouble bond; length as m-dashCH2, (where n = 1–3) have been successfully converted into new silacyclic or silamacrocyclic compounds in the presence of ruthenium–benzylidene complex (first generation Grubbs catalyst). The structures of both macrocyclic silaolefins have been confirmed using X-ray diffraction.