分子内の酸化還元を介するC（sp<sup>3</sup>）-H結合官能基化型環化反応

Abstract

Direct transformation of unactivated bond such as C-H bond is an important transformation. Because of its high utility from the viewpoints of atom economy and step economy, much effort has been devoted to the development of novel and more efficient strategies. Most of the reported processes have been relied on the use of active, transition metal (TM) catalysts. Unfortunately, this chemistry is hounded by the problem that stoichiometric amounts of oxidants, which become waste after the reaction, are required for the regeneration of the active oxidation state of TM. Needless to say, the use of toxic TM catalysts is also negative point from the economic and practical points of view. We have developed a novel type of C(sp3)-H bond functionalization without external oxidants, and, in some cases, TM catalysts. The key of this reaction is an intramolecular redox process, which is induced by intramolecular hydride shift. This reaction has several useful features: (1) the reaction proceeds via internal redox process, and hence, external oxidants are not required, (2) functionalization of the most tough C-H bond, C(sp3)-H bond, is involved, (3) three dimensional cyclic structures containing chiral centers are produced from non-chiral, linear substrates, (4) functionalization of remote C-H bond (more than five-atoms apart) is achieved. In this article, we want to describe the details of our endeavors to develop the target reactions, and its application to the construction of various useful fused-cycles which are otherwise difficult to achieve by the conventional methods.