ON THE 1,3-ISOMERIZATION OF NONRACEMIC ALPHA -(ALKOXY)ALLYL STANNANES

A set of optically active (E)-α-(alkoxy)allyl stannanes was prepared by reduction of the acyl stannanes with (R)-(+)-BINAL-H or LiAlH 4 -Chirald and protection of the resulting hydroxy stannanes with NOMCl or BOMCI. On treatment with BF 3 .OEt 2 these stannanes rearranged stereospecifically to the (Z)-γ-(alkoxy)allyl stannanes by 1,3-migration of Bu 3 Sn. The rearrangement was shown to take place by an intermolecular anti pathway. Addition of the γ-alkoxy stannanes to representative aldehydes afforded optically active syn-1,2-diol monoethers as the major diastereomers with high anti S E ' stereoselectivity