REACTION OF IMINES WITH SILENES - STABLE SILAZETIDINES

Silenes of the family (Me3Si)RSi=C(OSiMe3)R', 2, have been found to un dergo both [2+4] and [2+2] cycloadditions with imines R2C=NR, 3, to gi ve cyclic products, silatetrahydroisoquinolines, 4, or silazetidines, 5, respectively. If formed, the [2+4] adducts generally rearrange slow ly in the dark, or more rapidly when photolyzed, to the [2+2] adducts. When thermally decomposed in solution, the various silazetidines show ed different reaction pathways, yielding either the original silene an d imine or, in one case, the head-to-tail dimer of a silanimine plus a n alkene, nominally derived from the alternative retro [2+2] decomposi tion.