Non-stabilized and semi-stabilized phosphonium diylids of the type (C6H5)2P(CHR)(CHLiR) (5) show a greater nucleophilic reactivity toward carbonyl compounds than the corresponding monoylids (C6H5)2P(CHR)(CH2R) (8). Thus diylid 5a reacts readily at room temperature with sterically hindered ketones such as fenchone or di-t-butylketone. However, the residual negative charge in the intermediate adduct
(C 6 H 5)2 P(CHR)(CHLiR)(5)类型的非稳定化和半稳定化的磷鎓二碘化物对羰基化合物的亲核反应性高于相应的单酰基(C 6 H 5)2 P( CHR)(CH 2 R)(8)。因此,二碘化物5a在室温下容易与空间受阻的酮例如fenchone或二叔丁基酮反应。然而,中间加合物13中残留的负电荷减慢了向维蒂希产物的分解,并且可能是造成E中观察到的变化(通常增强)的原因。在非稳定的和半稳定的脂质的情况下的-选择性。