Design of Fine Acid Base Catalysts and their Utility in Selective Organic Synthesis

在本研究项目中，我们将注意力集中在合理设计真正有效的酸/碱催化剂，用于开发合成工艺，以实现普通酸/碱催化剂无法观察到的高反应性和选择性。在复杂的刘易斯酸化学中，成功地设计了一种新的手性双齿钛（IV）配合物，并可用于同时配位醛羰基，从而允许精确的对映体歧视，这种羰基的一种新的催化，实用的烯丙基三丁基锡醛的不对称选择性烯丙基化。该手性双齿钛配合物已成功地应用于硝酮或重氮乙酸酯的不对称1，3-偶极环加成反应。另一方面，相转移催化是一种非常有用的方法，通常涉及简单的实验操作，温和的反应条件，廉价且环境友好的试剂和溶剂，以及大规模反应。因此，由（S）-或（R）-联萘衍生的结构刚性的手性螺环铵盐被设计成新型的C_2对称手性相转移催化剂，并成功地应用于温和相转移条件下的高效催化对映选择性合成。最近，我们成功地设计了简化但活性非常高的手性相转移催化剂，用于实际不对称合成α-烷基和α，α-二烷基氨基酸。此外，我们还设计了手性螺旋型相转移催化剂，用于不对称Strecker反应大规模制备空间位阻α-烷基氨基酸。一种碗状的有机金属主体，三（2，6-二苯基苄基）-硅基，-甲锗基，和-锡化合物可以被制备，并应用于选择性有机转化。

In this research project, we focused our attention on the rational design of truly efficient acid/base catalysts for the development of synthetic processes in order to achieve the high reactivity and selectivity, not observable by ordinary, acid/base catalysts. In the sophisticated Lewis acid chemistry, a new, chiral bidentate Ti(IV) complex was successfully designed and can be utilized for simultaneous coordination to aldehyde carbonyls, thereby allowing the precise enantioface discrimination of such carbonyls for a new catalytic, practical enantioselective allylation of aldehydes with allyltributyltin. This chiral bidentate Ti(IV) complex has been successfully applied to asymmetric 1, 3-dipolar cycloaddition of nitrones or diazoacetates. On the other hand, phase transfer catalysis is a very useful approach that typically involves simple experimental operations, mild reaction conditions, inexpensive and environmentally benign reagents and solvents, and the large-scale reactions. Accordingly, structurally rigid, chiral spiro ammoniurn salts derived from commercially available (S)- or (R)-binaphthol have been designed as new C_2-symmetric chiral phase transfer catalysts and successfully applied to the highly efficient, catalytic enantioselective synthesis under mild phase transfer conditions. Quite recently, we have successfully designed simplified, yet very active chiral phase transfer catalysts for practical asymmetric synthesis of α-alkyl- and α,α-dialkylamino acids. In addition, chiral, helical-type phase transfer catalysts were newly designed for effecting asymmetric Strecker reaction for large-scale production of sterically hindered α-alkylamino acids. A bowl-shaped organometallic host, tris(2, 6-diphenylbenzyl)-silyl, -germyl, and -tin compounds can be prepared, and applied to selective organic transformations.