On the stereoselectivity of reactions of alkoxyallylstannanes and alkoxy aldehydes

Different behaviour is observed in tin(Iv) halide promoted reactions between the 2-(1-alkoxyethyl)prop-2-enylstannane 10 and the 4-alkoxypent-2-enylstannanes 1 with 2-alkoxy aldehydes, The chirality of the aldehyde would appear to dominate the stereoselectivity in the former case with the preferred addition following the chelation controlled mode, whereas the stannane dominates the stereoselectivity in the latter, The different behaviour of these two types of stannane may be a reflection of the coordination of the tin in the intermediate allyltin trihalides which are believed to be the reactive species involved in the reactions with the aldehydes.