Efficient Enantioselective Reactions of carbanions α to the Sulfur Functional Groups

自1999年以来，我们研究了利用有机硫化合物进行新的不对称合成。我们成功地开发了由β-硅乙基亚砜衍生的α-亚砜基碳离子的新的非对映选择性反应，在每个反应中，α， β-不饱和羰基化合物和醛只产生单一的非对映异构体。此外，所形成的烯醇酸酯与醛的后续反应也只能得到一个单一的立体异构体。这些结果显著地表明，这些反应可以通过手性亚砜控制四个连续的手性中心的立体化学。还研究了α-亚砜基碳离子的对映选择性反应。手性双恶唑存在下α-亚砜基碳离子与各种亲电试剂的反应。我们研究了与醛类、酮类、三氟甲基磺酸甲酯、三甲基硅酰氯和二氧化碳的反应。α-亚砜基苯基硫化物与α-亚砜基碳离子的反应发现，反应中更多的离子是通过动态动力学分解途径进行的。另一方面，由2-吡啶基硫化物生成的α-亚砜基碳离子，其立体化学性质与苯基苯硫化物反应的产物相反。结果表明，该反应是通过中间锂配合物构型反转的动态热力学分解途径进行的。此外，我们还研究了C-S键轴周围的旋转势垒引起的不对称反应。具有2,4,6-三异丙基苯基的1-亚砜基-2-甲酰基萘和2-酰基萘在亲核反应、Mukaiyama醛醇反应和还原反应中表现出极高的立体选择性。这些立体选择性是由C-S键轴周围的旋转势垒引起的，经1H核磁共振谱、x射线结构分析和MO计算。消去所得产物中的亚砜基，得到手性醇衍生物。少

Since 1999, we have studied on the new asymmetric syntheses using organosulfur sompounds. We stucceeded in developing of new diastereoselective reactions of the α-sulfinyl carbanion derived from β-silylethyl sulfoxides, which afforded only a single diastereoisomer in each reaction using aldehydes, and α, β-unsaturated carbonyl compounds. Furthermore, subsequent reaction of the formed enolates with aldehydes also afforded only a single stereoisomer These results strikingly show that these reactions can control the stereochemistry of the four consecutive chiral centers by a chiral sulfoxide.Enantioselective reactions α-sulfenyl carbanions were also studied. Reactions of α-sulfenyl carbanion with various electrophiles in the presence of chiral bisoxazolines. We examined the reactions with aldehydes, ketones, methyl trifluoromethylsulfonate, trimethylsilyl chloride, and carbon dioxide. The reaction of α-sulfenyl carbanion derived from α-stannylbenzyl phenyl sulfide was found that the react … More ion proceeds through a dynamic kinetic resolution pathway. On the other hand, α-sulfenyl carbanion derived from 2-pyridyl sulfide afforded the product having the stereochemistry opposite to the one obtained in the reaction of benzyl phenyl sulfide. This reaction was proved to proceed through a dynamic thermodynamic resolution pathway with inversion of configuration of the intermediate lithium complex.Furthermore, we have studied on the asymmetric reaction caused by the rotational barrier around the C-S bond axis. The 1-sulfinyl-2-formyl and 2-acylnaphthalenes having the 2,4,6-triisopropylphenyl group showed extremely high stereoselectivities in the nucleophilic reactions, Mukaiyama aldol reactions, and reductions. These stereoselectivities are shown to be caused by the rotational barrier around the C-S bond axis by tire ^1H NMR spectra, the X-ray structural analyses and the MO calculations. Elimination of the sulfinyl group from the obtained products afforded chiral alcohol derivatives. Less