Studies of Stereoceiective Preparation of 7-Membered Heterocycles Utilyzing Intramolecular

α，β-不饱和醛在β-位上含有(Alk-2-enyl)氨基部分的热反应使氮杂环丙烷的衍生物以很好到很好的产率得到。当这些基团是杂环的一部分时，形成了杂环体系融合的氮杂环衍生物。醛的亚胺也提供了氮杂环丙烷的衍生物。通过醛与活性亚甲基化合物的缩合反应得到的乙烯基底物，根据乙烯基和烯基上的取代基的种类，得到了氮杂环上的衍生物和/或杂化的Diels-Alder加合物。通过与β-(Alk-2-enyl)氨基丙烯醛的类似反应，得到了简单的氮杂环丙烷衍生物。丙烯醛的氮杂环化反应活性取决于α-位上的取代基(R)；α-位上的丙烯醛甲氧基基团尚不清楚，我们认为α-取代基的空间体积对环化步骤有影响。这些氮杂环的形成可以被认为是分子内的羰基、亚胺和烯烯反应，属于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构型的烯胺基团的底物被允许反应时，得到了具有4，5-顺式构型的氮杂环丙烷衍生物。模型反应的PM3分子轨道计算表明，氮杂环的形成是由两个连续的轨道允许的反应组成的：1，6-烯基氨基上的烯丙基氢转移到羰基氧(或免疫氮)上，得到共轭的亚甲亚胺叶立德和1，7-亚甲亚胺叶立德的1，7-电环化反应。为了获得更多的反应机理的信息，亚胺和羰基烯的反应都在烯基氨基部分带有手性中心的醛上进行了自自燃手性转移到氮杂环上。

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.