THE REACTION OF TRIS(TRIMETHYLSILYL)SILYLLITHIUM WITH DIBENZOSUBERENONE

Tris(trimethylsilyl)silyllithium (1) reacts with dibenzosuberenone in ether to give, after carbonyl addition of the lithium silanide and lit hium trimethylsilanolate elimination according to a modified Peterson mechanism, the transient silene 5 which is trapped by addition of exce ss 1 at the Si=C double bond to afford 4-hexamethyl-2,3,3-tris(trimeth ylsilyl)tetrasilane (7), When the same reaction is carried out in dime thoxyethane, no silene is generated, but after carbonyl addition of 1 at dibenzosuberenone a 1,3-Si,O-trimethylsilyl migration occurs, produ cing the lithium silanide 8 which undergoes an intramolecular addition at the 10,11-C=C double bond of the dibenzocycloheptatriene system un der formation of a bicyclic organolithium derivative which reacts with excess dibenzosuberenone to afford the alcohol 10. Compounds 7 and 10 were fully characterized by their IR, NMR and MS data, for 10 the res ults of an X-ray crystal structure analysis are also given.