THE ADDITION OF GAMMA-(TRIMETHYLSILYL)ALLYLBORONATES TO IMINES

The addition of gamma-(trimethylsilyl)allylboronates to imines is described and compared with the addition of simple allylboronates to imines. The addition of gamma-(trimethylsilyl)allylboronates to imines is found to be more efficient than the addition of simple allylboronates to imines. The stereoselectivity is dependant upon the nature of the imine; imines derived from aromatic aldehydes give anti products and imines derived from aliphatic aldehydes give syn products. Proof of stereochemistry was established by conversion of the anti and syn derivatives to their respective Z- and E-dienes by a methylation/E-2 elimination process. With alpha-alkoxy aldehydes the reaction proceeds with excellent selectivity giving the product of Felkin-Ahn addition.