Newly Designed Asymmetric Reaction Sites Induced by Rotational Barrier around the Carbon-Sulfur Bond Axis and their Reactions

研究了1-磺酰基萘的2-位上的甲醛或亚氨基的亲核加成反应。考察的反应有：格氏反应、与烷基锂的烷基化反应、LiAlH_4或二异丁基氢化铝的还原反应和向山羟醛缩合反应。立体选择性被发现依赖于亚磺酰基基团上的取代基。在含2，4，6-三异丙基苯基的萘甲醛的反应中，可获得高的立体选择性（>98：2）。另一方面，叔丁基亚磺酰基-萘甲醛或-萘甲亚胺显示较低的立体选择性，然而，在良好的雅阁的非对映异构体的比率所造成的旋转障碍周围的碳-硫键轴证明了核磁共振分析。结果表明，1-（2，4，6-三异丙基苯基）亚磺酰基-2-萘甲醛或-萘甲亚胺的高立体选择性是由高转动势垒引起的 关于我们 在碳-硫键轴周围，因为上面显示的所有反应都以高的立体选择性进行，而与螯合或非螯合过渡态无关。此外，1-对甲苯基亚磺酰基-苯甲醛或-苯基甲亚胺，其中围绕碳-硫键轴的自由旋转被假定，仅在反应中通过螯合过渡态显示出高的立体选择性。可以从产物中除去亚磺酰基。例如，可以非常有效地制备特别是具有两个芳族基团的光学活性醇。Dibal还原β-酮基亚砜具有完全的立体选择性，其立体选择性受β-位硅基的控制。在本研究中，我们还成功地设计了一种新的具有旋转势垒的手性配体。因此，1-和1 '-位上分别含有亚磺酰基和二苯基亚磺酰基的二茂铁基化合物是一种高效的手性配体，可以用于钯催化丙二酸酯的烯丙基化反应，通过这些研究，我们可以发展新的由转动势垒引起的立体选择性反应，包括一种新的利用碳-硫键轴转动势垒的立体选择性反应的概念。少

Nucleophilic addition reactions to the carbaldehyde or imino groups at the 2-position of 1-sullinylnaplithalene have been examined. The reactions examined are as follows : Grignard reactions, alkylation reactions with alkyllithiums, reductions with LiAlH_4 or diisobutylaluminum hydride and Mukaiyama aldol reactions. Stereoselectivity was found dependent on the substituents on the sulfinyl group. High stereoselectivity (>98:2) could be achieved in the reactions of suffinylnaphthaldehyde having a 2,4,6-triisopropylphenyl group. On the other hand, tert-butylsulfinyl-naphthaldehyde or -naphthylmethanimine showed lower stereoselectivities which, however, were in good accord to the ratio of the diastereomers caused by the rotational barrier around the carbon-sulfur bond axis evidenced by the nmr analyses. We have concluded that the high stereoselectivity in the reactions of 1-(2,4,6-triisopropylphenyl)sulfinyl-2-naphthaldehyde or -naphthylmethanimine is caused by the high rotational barrier … More around the carbon-sulfur bond axis, because all the reactions shown above proceeded with high stereoselectivities irrespective of the chelating or non-chelating transition states. Furthermore, 1-p-tolylsulfinyl-benzaldehyde or -phenylmethanimine, in which a free rotation around the carbon-sulfur bond axis is assumed, showed high stereoselectivity only in the reaction through chelating transition states. The sulfinyl group can be removed from the products. For example, optically active alcohols especially having two aromatic groups can be prepared very efficiently. Thus, the present reaction provides a new efficient preparative method for optically active methanol having two different aromatic groups, with a similar bulkiness such as phenyl-p-tolylmethanol which is mostly difficult to prepare by the asymmetric reduction.Reduction of β-ketosuklfoxides with Dibal was found to show complete stereoselectivity which was controlled by the silyl group at the β-position. In this study a new chiral ligand having a rotational barrier for enantioselective reactions was also successfully designed. Thus, a ferrocenyl compound having sulfinyl and diphenylphosfinyl groups at 1-and 1'-positions was found to be an afficient chiral ligand for the allylation of malonate with a Pd catalyst.Through these studies, we could develop new stereoselective reactions caused by rotational barriers which includes a new concept of stereoselective reactions using a rotational barrier around the carbon-sulfur bond axis. Less