1,2-diaza-3-silacyclopent-5-ene - Synthesis and reactions

The dilithium salt or bis(tert-butyl-trimethylsilylmethy-len)ketazine (1) forms an imine-enamine salt. 1 reacts with halosilanes in a molar ratio of 1:1 to give 1,2-diaza-3-silacyclopent-5-enes. Me3SiCH=CCMe3 [N(SiR,R')-N=C-C]HSiMe3 (2-7).(2: R,R' = Cl; 3: R CH3, R' = Ph; 4: R = F, R' = CMe3; 5: R = F, R' = Ph; 6: R F, R' = N(SiMe3)2; 7: R = F, R' = N(CMe3)SiMe3). In the reaction of 1 with tetrafluorosilane the spirocyclus 8 is isolated. The five-membered ring compounds 2-7 and compound 9 substituted on the silicon-fluoro- and (lert-butyltrimethylsilyl) are acid at the C(4)-atom and therefore can be lithiated. Experiments to prepare lithium salts of 4 with MeLi, n-BuLi and PhLi gave LiF and the substitution-products 10-12. 9 forms a lithium salt which reacts with ClSiMe3 to give LiCl and the SiMe3 ring system (13) substituted at the C(4)-atom. The ring compounds 3-7 and 10-12 form isomers, the formation is discussed. Results of the crystal structure and analyses of 8, 10 12, and 13 are presented.