Elucidation of Mechanism on the Heteroatom-Directed Stereoselection and its Application to Organic Synthesis.

为了阐明杂原子在烯丙基取代烯烃的亲电加成反应中对非对映选择性的作用，考察了烯丙基胺的氨基，因为氨基的电子性质能够通过改变氮原子上的取代基来系统地控制，所述氮原子上的取代基既涉及氮原子上的孤对电子，也涉及C-然而，现有的方法不能获得空间上限定的不对称取代的胺，并且已经开发了两种合成方法。第一种是钯催化4-乙烯基-1，3-二氧六环-2-酮转化为4-乙烯基-1-氧杂-3-氮杂环己烷-2-酮。第二种是银催化N-对甲苯磺酰基O-（2，3-丁二烯基）氨基甲酸酯氨环化合成N-对甲苯磺酰基-4-乙烯基-2-恶唑烷酮。N-取代的3-氨基-4-戊烯-1-醇的碘醚化得到顺式和反式-2-碘甲基-3-氨基四氢呋喃的混合物。在这个环化的顺式/反式选择性进行检查，改变N-取代基（乙酰基，苯甲酰基，对硝基苯甲酰基，三氟乙酰基，对甲苯磺酰基，甲磺酰基，和三氟甲磺酰基）。环化反应的反应活性以取代基的顺序降低，而选择性（顺式/反式）以取代基的顺序增加。在此基础上，提出了异原子效应的精确机理。

In order to elucidate the role of heteroatoms on the diastereoselection in the electrophilic addition reaction to allylically substituted olefins, the amino group of allylic amines is examined, because the electronic nature of the amino group is able to be controlled systematically by changing the substituents on the nitrogen atom both in terms of the lone pair electrons on the nitrogen atom and also in terms of the sigma electrons of the C-N bond.The sterically defined unsymmetrically substituted amines are, however, not available by the existing methods and two synthetic methods have been developed. The first is the palladium catalyzed transformation of 4-vinyl-1, 3-dioxane-2-ones into 4-vinyl-1-oxa-3-azacyclohexan-2-ones. The second is the silver catalyzed aminocyclization of N-tosyl O-(2, 3-butadienyl) carbamates to N-tosyl-4-vinyl-2-oxazolidinones. By these reactions unsymmetrically substituted allylic amines are prepared and used for an iodoetherification.Iodoetherification of N-substituted 3-amino-4-penten-1-ols provides a mixture of cis and trans-2-iodomethyl-3-aminotetrahydrofurans. The cis/trans selectivity in this cyclization is examined, changing the N-substituents (acetyl, benzoyl, p-nitrobenzoyl, trifluoroacetyl, p-toluenesulfonyl, methanesulfonyl, and trifluoromethanesulfonyl). The reactivity in the cyclization decreases in this order of substituents, while the selectivity (cis/trans) increases in this order. Based on these results, a precise mechanism of the HETEROATOM EFFECT is proposed.