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

为了阐明杂原子在烯烃亲电加成反应中对非对映选择性的作用，对烯丙基胺的氨基进行了研究，因为氨基的电子性质可以通过改变氮原子上的取代基来系统地控制，既可以通过氮原子上的孤对电子来控制，也可以通过C-N键的sigma电子来控制。然而，空间定义的不对称取代胺不能通过现有的方法和两种合成方法来实现。第一种是钯催化4-乙烯-1，3-二氧六环-2-酮转化为4-乙烯-1-氧杂-3-氮杂环己酮。第二种是银催化N-对甲苯磺基O-(2，3-丁二烯基)氨基甲酸酯的氨基环化反应，合成N-对甲苯磺基-4-乙烯-2-恶唑烷酮类化合物。通过这些反应，合成了不对称取代的烯丙基胺，并将其用于碘醚化反应。N-取代的3-氨基-4-戊烯-1-醇的碘醚化反应生成了顺式和反式-2-碘甲基-3-氨基四氢呋喃的混合物。通过改变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)，考察了环化反应中的顺反选择性。环化反应的活性按取代基的顺序降低，而选择性(顺式/反式)按顺序增加。在此基础上，提出了杂原子效应的精确机制。

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.