Preparation of α-substituted γ-alkoxyallylstannanes from β-tributylstannyl acrolein acetals: scope of the method and primary rationalization of the obtained results

α-Substituted γ-alkoxyallylstannanes were obtained from β-tributylstannyl acrolein acetals when reacted with lower order magnesium cyanocuprates in the presence of boron trifluoride at low temperature. In the case of n-alkylcyanocuprates an anti SN2′ substitution on a cisoid conformation appears to be the main reaction pathway. However, subtle competitions with other mechanisms may occur depending on the experimental conditions, on the reagents or on the substrates. These drawbacks constitute limitations for the use of the method especially when enantioenriched α-substituted γ-alkoxyallylstannanes are desired.