Synthesis of Chiral Allenyl Silanes and Homopropargylic Amines from Aldimines

Significance

This is the first report of asymmetric allenylboration of imines, which provides enantio­pure homopropargylic amines 6 bearing an α-chiral center. Readily available alkynyl Grignard reagents can be homologated to the key silylallenylboron 3 quantitatively. Although mostly aromatic aldimines 4 were tested, the enantioselectivity was uniformly excellent. The key intermediate 3 was also shown to furnish enantiopure silylallenes 7 by simple protonolysis. Allenyl silanes are established useful allylating reagents.