Studies of Stereoceiective Preparation of 7-Membered Heterocycles Utilyzing Intramolecular

α，β-不饱和醛的热反应在β-位置上含有一个（烷烃-2-烯基）氨基酸片段，使氮卓类衍生物的收率很高。当这些基团是杂环的一部分时，形成杂环体系融合的氮卓类衍生物。醛的亚胺也产生了氮平类衍生物。由醛类与活化的亚甲基化合物缩合反应得到的乙烯基底物，根据乙烯基和烯基部分上取代基的种类，得到氮平类衍生物和/或杂Diels-Alder加合物。β-（烷烃-2-烯基）氨基丙烯醛的类似反应得到简单的氮平类衍生物。丙烯醛形成氮平环的反应活性取决于α-位置的取代基(R)；α-位置含甲氧羰基的丙烯醛仍不清楚，我们认为α-取代基的空间体积可能影响环化步骤。这些氮平环的形成可以看作是分子内羰基、亚胺和烯烃的反应，被归类为III型烯反应。其中，反应以高度立体选择性的方式进行；当具有e构型的烯基氨基的底物反应时，得到具有4,5-顺式构型的氮卓类衍生物。模型反应的PM3分子轨道计算表明，氮平环的形成是由两个连续的轨道允许反应组成的；烯基胺部分的烯丙基氢向羰基氧（或免疫氮）的1,6移位，导致偶联亚甲基酰基和1,7电环化。为了进一步了解反应机理，在亚胺和羰基烯反应中，在烯基胺部分有一个手性中心的醛进行了自牺牲手性转移到氮平环上。

The thermal reaction of the α,β-unsaturated aldehydes bearing an (alk-2-enyl) amino moiety at the β-position gave the azepine derivatives in good to excellent yields. When these groups were a part of heterocycles, the azepine derivatives fused by the heterocyclic systems were formed. The imines of the aldehydes also afforded the azepine derivatives. The vinyl substrates, obtained by the condensation reaction of the aldehydes with activated methylene compounds, gave the azepine derivatives and/or hetero Diels-Alder adducts depending on the kind of the substituents both on the vinyl and alkenyl parts. The similar reactions of β-(alk-2-enyl) aminoacroleins gave the simple azepine derivatives. The reactivity for the azepine-ring formation of the acroleins depended on the substituent (R) on the α-position; the acrolein bearing methoxycarbonyl group at the α-position is still obscure, we suggest that the steric bulkyness of the α-substituents should affect on the cyclization step.These azepine-ring formation could be regarded as the intramolecular carbonyl, imine, and olefin ene reactions classified as a Type III ene reaction. Therein, the reactions proceeded in a highly stereoselective manner; when the substrates having alkenylamino moieties with the E-configuration were allowed to react, the azepine derivatives with the 4,5-cis configuration were obtained. The PM3 molecular orbital calculations of the model reactions suggest that the azepine-ring formation is constituted of two consecutive orbital-allowed reactions; 1,6-shift of the allylic hydrogen of the alkenylamino moiety to the carbonyl oxygen (or immune nitrogen) leading to conjugated azomethine ylides and 1,7-electrocyclization of the azomethine ylides.In order to obtain further informations on the reaction mechanism, both imine and carbonyl ene reactions using the aldehydes bearing a chiral center at the alkenylamino moiety have performed a self-immolating chirality transfer to the azepine ring.