Studies on the reactions of chiral dianions

在100%e.E.中合成了手性b-羟基砜(I)、-羟基砜(II)和-羟基-硝基化合物(III)。通过贝克氏酵母还原相应的酮。用二异丁基氢化铝还原手性酮亚砜生成非对映异构体羟基亚砜(IV)。I和IV的双阴离子与烷基化试剂或羰基化合物反应，形成立体选择性的碳-碳-碳键。虽然金属阳离子的分子内络合作用可能在IV的反应中起重要作用，但在I的双阴离子中，溶剂分子与金属阳离子的配位可能占主导地位。在这些双阴离子的反应中，羰基化合物攻击金属阳离子一侧的碳离子，而烷基化试剂的方法被发现是由空间效应控制的，而与阳离子无关。在IV的双阴离子中，碳负离子发生构型相互转化，金属阳离子与相邻基团的分子内螯合作用在此过程中起重要作用。从I-IV出发，以100%的e.e.e合成了许多手性化合物，如-，-内酯、四氢呋喃和烯丙基醇类化合物，也就是说，I-IV是非常有用的手性构筑单元。

Chiral b-hydroxysulfones (I), -hydroxysulfones (II), and -hydroxy-nitrocompounds (III) were prepared in 100% e.e. by Baker's yeast reduction of the corresponding ketones. Reduction of chiral -ketosulfoxides with diisobutylaluminum hydride produced diastereoisomeric -hydroxysulfoxides (IV) in 100% e.e. The reaction of the dianions of I and IV with alkylating reagents or carbonyl compounds lead to the stereoselective carbon-carbon-carbon bond formation. While the intramolecular chelation of a metal cation may play an important role in the reaction of IV, the coordinatio of solvents molecules with a metal cation may be predominat in the dianion of I.In the reactions of these dianions the carbonyl compounds attack the carbanion on the side of a metal cation, whereas the approach of the alkylating reagents was found to be governed by the steric effects regardless of the cation. In the dianion of IV the configurational interconversion of the carbanion took place, and the intramolecular chelation of a metal cation with the adjacent group is assumed to play an important role in the conversion.From I-IV many chiral compounds such as -, -lactones, tetrahydrofurans, and allylic alochols were synthesized in 100% e.e., that is to say, I-IV are very useful chiral building blocks.