Diverse reactivity of an isolable dialkylsilylene toward imines.

ABSTRACT

The reactions of isolable dialkylsilylene 10 with various aldimines proceed smoothly at low temperatures to give diverse products depending on the substituents on the imine. The reactions of 10 with 4-XC(6)H(4)CH=NPh [X = H (11a), MeO (11b), and Cl (11c)] give the corresponding silaaziridines 12a-12c in high yields, which are thermally very stable and remain intact in the air and moisture for a long time. In contrast, the reactions of 10 with 4-F(3)CC(6)H(4)CH=NPh (11d) and 3,5-(F(3)C)(2)C(6)H(3)CH=NPh (11e) having strong electron-withdrawing aryl substituents on imine carbon are accompanied by 1,2-trimethylsilyl migration rather unexpectedly to give silaazetidines 13d-13e incorporated into a bicyclo[3.2.0]heptane ring. The reaction of 10 with N-benzylbenzaldimine 11f affords the corresponding (dibenzylamino)silane 14f in a moderate yield. Molecular structures of 12a-12c, 13d-13e and 14f were determined by X-ray crystallography. All these reactions are proposed to occur via the initial formation of the corresponding imine silaylides, while the subsequent reactions leading to the final products are controlled by the electronic structure of the ylide depending on the substituents. N-phenylbenzophenimine 11g does not react with 10.