Study on the development of highly selective catalytic reactions mediated by nitrogen heterocycles

研究了以8-苯基甲基为手性助剂的n -烷氧羰基甲基吡啶基非对映体环丙烷化反应中的取代基效应。研究发现，引入一个给电子的4-甲氧基，与t-Bu取代的甲基丙二腈底物的反应选择性高达964。虽然含有芳香取代基的底物的选择性可达8317，但含有脂肪取代基的其他底物的选择性不超过7030。为了从整体上提高选择性，我们决定用8-苯基薄荷胺代替8-苯基薄荷醇作为手性助剂。该胺的选择性高达8911，收率为97%。在t-Bu取代甲基丙二腈底物上的非对映体环丙烷化反应的选择性高达2 98，整体上的选择性（63:37 ~ 12:88）也高于酯系对其他底物的选择性。酰胺系主要产物的绝对立体化学与酯系主要产物的绝对立体化学相反。改变反应条件可以得到含有环亚胺基团的双环产物。基于在吡啶环中引入手性可以实现手性源的再循环的思想，研究了几种在3位有手性助剂的手性吡啶。然而，不幸的是，没有观察到不对称诱导。对氯酮与共轭烯烃底物之间的环丙烷化反应进行了研究，发现该反应是由4-二甲氨基吡啶催化的

Examination of substituent effects in the diastereomeric cyclopropanation reaction of N-alkoxycarbonylmethyl pyridinium ylides bearing an 8-phenylmenthyl group as the chiral auxiliary was carried out. It was found that introduction of an electron donating 4-methoxy group gives rise to selectivities up to 964 for the reaction with a t-Bu substituted methylidene malononitrile substrate. Although selectivities up to 8317 could be observed for substrates bearing aromatic substituents, those for other substrates bearing aliphatic substituents did not exceed 7030. In order to raise the selectivity as a whole, we decided to examine 8-phenylmenthylamine in the place of 8-phenylmenthol as the chiral auxiliary. The amine could be prepared with selectivities up to 8911 and 97% yield. Examination of the diastereomeric cyclopropanation reaction on the t-Bu substituted methylidene malononitrile substrate resulted in selectivities up to 2 98, and as a whole the selectivity (63:37 to 12:88) was also higher than that in the ester series for other substrates. It was also found that the absolute stereochemistry for the major products of the amide series was opposite of that of the major product of the ester series. Modification of reaction conditions gave rise to bicyclic products bearing a cyclic imide moiety. Based upon the idea that introduction of chirality into the pyridine ring would allow for recycling of the chiral source, several chiral pyridines with chiral auxiliaries in the 3 position were examined. Unfortunately, however, no asymmetric induction could be observed. In an examination of the cyclopropanation reaction between a chloroketone and a conjugated olefin substrate, it was found that the reaction is catalyzed by 4-dimethylaminopyridine