Asymmetric synthesis of alpha-amino allyl,benzyl, and propargyl silanes by metalation and rearrangement

[reaction: see text] Metalation of a Boc-protected N-silylamine alpha to nitrogen results in migration of the silicon from nitrogen to carbon (reverse aza-Brook rearrangement), yielding an alpha-amino silane. The Boc group acts initially as a metalation-directing group and then to stabilize the nitrogen anion, providing a driving force for the rearrangement. In the presence of (-)-sparteine, the new chiral center is formed in >90% ee from allyl, benzyl, and propargylamines.