Hypervalent Iodine(III)Compounds in Organic Synthesis

在本项目中，我们研究了利用高价碘（III）化合物开发新的反应及其在合成具有生物活性的天然产物中的应用。i)我们最近在极性和低亲核溶剂（如CF_3CH_2OH和（CF_3）_2CHOH）中开发了使用苯基吡啶（III）双（三氟乙酸酯）（PIFA）直接叠氮化对取代苯酚醚的新方法。通过紫外和ESR光谱研究发现，反应是通过阳离子自由基中间体进行的。该反应对氧、碳和硫亲核试剂的引入是有效的。我们可以把这个反应应用于分子内的氧化酚醛偶联。另一方面，在CH_3CN中，烷基叠氮化反应发生在对取代苯酚的苯基位置。ii)虽然已知具有叠氮或氰基配体的试剂对各种化合物的叠氮化或其他反应非常有用，但它们太不稳定而无法分离。可以制备具有叠氮基、氰基和硝基配体的结晶性和空气稳定性的环碘。iii)我们最近报道了通过PIFA诱导对取代的酚氨基醌环化合成海洋抗肿瘤生物碱discorhabdin C。发现含氨基醌的苯酚衍生物在微米或m位上的环化为合成螺二烯酮和h -氮平类化合物提供了一条通用的途径。此外，还开发了通过裂解-内酰胺环合成异虫丁类生物碱基本结构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.