Hypervalent Iodine(III)Compounds in Organic Synthesis

在这个项目中，我们研究了高价碘（III）化合物的新反应及其在生物活性天然产物合成中的应用：i）我们最近开发了一种新的邻取代苯酚醚的直接叠氮化反应，在极性和低亲核性溶剂如CF_3CH_2OH和（CF_3）_2中，通过紫外光谱和电子自旋共振（ESR）光谱研究发现，反应是通过阳离子自由基中间体进行的。该反应对于引入氧、碳和硫亲核试剂是有效的。该反应可应用于分子内氧化酚偶联反应。另一方面，在CH_3CN中，对位取代酚醚的苄基位发生烷基叠氮化反应。ii）虽然已知具有叠氮基或氰基配体的试剂对各种化合物的叠氮化反应或其它反应是非常有用的，但它们太不稳定而不能分离。三）我们最近报道了海洋抗肿瘤生物碱discorhabdin C的全合成，通过PIFA诱导的环化的p-取代酚氨基醌。发现在ω-或m-位上带有氨基醌的苯酚衍生物的环化提供了一条合成螺二烯酮和IH-氮杂卓的通用路线。此外，还发展了通过β-内酰胺环断裂合成discorhabdin生物碱的基本结构N，S-缩醛的新方法。

In'this project, we have studied on the developement of novel reactions using hypervalent iodine(III)compounds and the application to the synthesis of biologically active natural products.i)We recently developed the novel direct azidation of p-substituted phenol ethers using phenyliodine(III)bis(trifluoroacetate)(PIFA)in polar and low nucleophilic solvents such as CF_3CH_2OH and(CF_3)_2CHOH.We found that the reaction proceeds via cation radical intermediates by UV and ESR spectroscopic studies. The reaction is effective for introductions of oxygen, carbon, and sulfur nucleophiles. We could apply the reaction to the intramolecular oxidative phenolic coupling. On the other hand, in CH_3CN the alkyl azidation occurrs at the benzylic position of p-substituted phenol cthers.ii)Although the reagents having azido or cyano ligands are known to be quite useful for the azidation of various compounds or for other reactions, they are too labile to be isolated. The cyclic iodinanes having azido, cyano, and nitrooxy ligands, which are crystalline and air-stable could be prepared.iii)We recently reported the total synthesis of marine antitumor alkaloid, discorhabdin C by PIFA induced cyclization of p-substituted phenolic aminoquinones. It was found that the cyclization of phenol derivatives bearing aminoquinones at the omicron-or m-position provides a versatile route to spirodienones and lH-azepines. Furthermore, the novel synthetic method for N,S-acetal, which is the essential structure of discorhabdin alkaloids, by the cleavage of the beta-lactam ring was also developed.