一価のカチオン性ヨウ素反応剤を用いるアルキンの求電子的環化反応

Cationic iodine(I)-mediated electrophilic cyclization, termed iodocyclization, allows ring formation and iodination at the same time. In particular, iodocyclization of alkynes as substrates gives cyclic products containing C(sp 2)-I bond, that would be able to introduce various substituents by performing well-established cross-coupling reactions afterwards. Thus, the iodocyclization of alkynes is suitable for diversity-oriented synthesis of cyclic compounds, and has been extensively studied over the past few decades. On the other hand, there are many problems such as 1) overreaction caused by iodine reagents, 2) poor selectivity of cyclic mode (endo/exo), and 3) difficulty of cyclization itself. The author has solved these problems and systematically developed practical methods for synthesizing heterocyclic and carbocyclic rings using the iodocyclization. This article also describes dearomative spirocyclization of phenol derivatives leading to three- dimensional polycyclic compounds.