Generation and Reactivity of a New Heterocyclic Silylene, a Silaazaanthracene

The cyclic silylene 6, a silaazaanthracene derivative, which possesses 14-electrons, has been generated by the reduction of 10,10-dichloro-5-methyl-5,10-dihydrophenazasiline (5) with lithium naphthalenide. Reactions of 6 with 2,3-dimethyl-1,3-butadiene, isoprene, and triethylvinylsilane gave the corresponding silylene-trapping products, 7, 8, and 9, in moderate yield. Pseudoaromatic stabilization of the cyclic silylene 6 was not observed, possibly due to the fact that the three rings are not coplanar.