Thermolysis reactions of 2-methoxy-2-(o-N,N-dimethylaminomethyl)-phenyl-3-trimethylsilyl-5,5-dimethyl-2-silahexane

In the neat now vacuum pyrolysis of 2-methoxy-2-(o-N,N-dimethylaminomethyl) phenyl-3-trimethybilyl-5,5-dimethyl-2-silahexane (4) at 600 degrees C and i ts static thermolysis at 350 degrees C, 2,3-benzo-5-aza-1-silacyclohexane ( 5) has been obtained in 97% and 46% yields, respectively. Product 5 might h ave been formed via an intramolecular rearrangement involving a zwitterioni c species generated from the pentacoordinated silene Si-atom. From trapping experiments with an excess of Me3SiOMe or MeOH, we have obtained 2-(o-N,N- dimethylaminomethyl)phenyl-2-methoxy-5,5-dimethyl-2-trimethylsiloxy-2-silah exane (6) and 2-(o-N,N-dimethylaminomethyl)phenyl-2-methoxy-5,5-dimethyl-2- silahexane (7) formed via an intermolecular protodesilylation reaction rath er than through trapped products of the silene.