Asymmetric Cycloaddition Using Coordination Ability of Heteroatom with Organometallics

有机化学中的杂原子作为有机金属的手性配体，已成为不对称合成的有力工具。我们把重点放在硫原子上，引入了一个手性分子，它可以与有机金属配位。因此，本研究项目的目的是开发二乙基锌等有机金属化合物在手性樟脑配体存在下与醛的加成反应，这些配体含有硫化物或亚硫醚。此外，β-亚磺酰基化合物中亚磺基作为手性助剂的有效性，它可以在烯丙基金属化合物的烯丙化反应中与Lewis酸形成七元络合物。我们合成了一些樟脑衍生的硫化物和亚砜，并选择了苯甲醛和二乙基锌的不对称加成反应。在优化的反应条件下，苯甲醛与二乙基锌反应生成(S)-1-苯基-1-丙醇。2.在Lewis酸存在下，手性β-亚磺醛与烯丙基金属化合物发生不对称加成反应。尽管使用α-亚磺酰基化合物进行不对称缩合反应的报道很多，但由于β-亚磺酰基化合物的不对称加成反应在络合控制方面的性能较差，因此很少有人对其进行研究。因此，我们合成了手性β-亚硫酰基化合物，即手性对甲苯基亚磺酰基芳醛，并考察了非对映选择性加成反应。在四氯化钛存在下，3-亚磺基呋喃与三苯基烯丙基锡的加成反应具有很高的非对映选择性，得到了高烯丙醇。另一方面，亚磺醛与四氯化锡类似的反应得到了另一种非对映异构体醇，手性亚磺酰基取代的亚硫醛也得到了类似的结果。

Heteroatoms in organic chemistry have become a powerful tool for asymmetric synthesis as a chiral ligand with organometals. We focused on the sulfur atom, incorporated a chiral molecule, which could coordinate with organometals. The aim of this resaerch project is thus to develope an addition reaction of such organometalic compounds as diethylzinc to an aldehyde in the presence of chiral camphor-derived ligands containing the sulfur as sulfides or sulfoxides. Furthermore, the effectiveness of a sulfinyl group in the beta-sulfinyl carbonyl compounds, as chiral auxiliary, which may form a seven-membered chelate with a Lewis acid in the allylation by allylmetal compounds.1. We synthesized some, camphor-derived sulfides and sulfoxides and selected the enantioselective addition of bezaldehyde with diethylzinc. When benzaldhyde was reacted with diethylzinc using beta-oxysulfides, (S) -1-phenyl -1-propanol was obtained in up to 82%e.e.under the optimized conditions.2.We undertook the asymmetric addition of an allylmetal compound to chiral beta-sulfinyl aldehyde in the presence of a Lewis acid. Despite of numerous reports for asymmetric condensations using alpha-sulfinyl carbonyl compounds, little work has been done on the asymmetric addition to beta-sulfinyl carbonyl compounds because of its low performance in chelation control. We thus synthesized chiral beta-sulfinyl carbonyl compounds i.e., chiral p-tolylsulfinyl fyrylaldehydes and examined the diastereoselective addition reactions. The addition of allyltriphenylstannane to 3-sulfinylfurfural in the presence of titanium (IV) tetrachloride proceeded with high diastereoselectivity to give the homoallyl alcohol. On the other hand the similar treatment of the sufinyl aldehyde with tin (IV) tetrachloride afforded the other diastereoisomeric alcohol, exclusively.The similar results were also obtained in the case of chiral, sulfinyl-substituted thienyl aldehyde.