Methylmesitylneopentylsilene: Synthesis and Study of Its Dimerization

Methylmesitylneopentylsilene Me(Mes)Si=CHCH2tBu 1 is prepared as reactive intermediate by the reaction of methyl(mesityl)vinylfluorosilane 2 with tBuLi.It can be evidenced by trapping reactions with tBuLi (excess) or 2,3-dimethylbutadiene.Without trapping agent, the molecules dimerize to form 4 different isomers of 1,3-disilacyclobutanes 4 (a-d).The Z/Z isomer 4d is the major dimer (83%).Its crystal structure is reported.The influence of the ratio for E-l to Z-l (93/7) on the stereochemical distribution of dimers is discussed.