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.
在卤化
锡(IV)促进的 2-(1-烷氧基乙基)丙-2-烯基
锡烷 10 和 4-烷氧基戊-2-烯基
锡烷 1 与 2-烷氧基醛的反应中,观察到了不同的行为。在前一种情况下,醛的手性似乎主导着立体选择性,优先加成遵循螯合控制模式,而在后一种情况下,
锡烷主导着立体选择性。这两种
锡烷的不同表现可能反映了中间体烯丙基三卤化
锡中
锡的配位情况,据信,烯丙基三卤化
锡是参与与醛反应的反应物。