Mesityl[tris(trimethylsilyl)silyl]methanol (1) reacts with strong bases with elimination of trimethylsilanolate according to a Peterson‐type mechanism, the outcome of the reaction being dependent on solvent, temperature, and nature of the organometallic base applied. Thus, 1 was converted by treatment with MeLi in ether at –78°C to (E)‐1,2,3,8a‐tetra ‐hydro‐1‐mesityl‐5,7,8a‐trimethyl‐2,2,3,3‐tetrakis (trimethylsi‐lyl)‐2,3‐disilanaphthalene (3), formally a [2 + 4] cyclodimer of the transient silene (Me3Si)2Si=CHMes (2). The reaction of 1 with PhMgBr in THF after some days resulted in the formation of (Z)‐3,4‐dimesityl‐1,1,2,2‐tetrakis(trimethylsilyl) ‐1,2‐disilacyclobutane (6) as the main product besides small quantities of 3, the polysilane (Me3SiSi(SiMe3)2CH2Mes (10), and the alkoxysilane (Me3Si)3SiCH(Mes)OSi(Si‐Me3)2CH2Mes (7). Compound 6, the formal [2 + 2] cycloadduct of 2, can also be obtained by thermal treatment of 3 and is considered to be the thermodynamically more stable silene dimer whereas 3 is the kinetically preferred product. At high LiBr concentrations in the reaction mixture 1 was converted by PhMgBr in THF to (E)‐2,4‐dimesityl‐1,1,3,3‐tetrakis(tri‐ methylsilyl)‐1,3‐disilacyclobutane (13) besides 6 and [bis(tri‐methylsilyl)silyl]mesityl(trimethylsiloxy)methane (11). The unforeseen formation of 13 is discussed as proceeding via the silene‐lithium bromide adduct (Me3Si)2Si(Br)CH(Li)Mes (12). In the absence of LiBr 1 was converted by MeLi in THF at –78°C to 11 and the trisilane (Me3Si)2Si(Me)CH2Mes (4b). Probable pathways of the formation of all new compounds are discussed. For 6 and 13 the results of the X‐ray structural analyses are given.
- 2,3‐Disilanaphthalene, tetrahydro‐
- Silene dimerization