Controllable transformation of indoles using iodine(III) reagent
Yinxiang Jian1,2, Peng Liang1,3, Xiaoyan Li1,2
1Natural Products Research Centre, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, People's Republic of China. maxf@cib.ac.cn.
Abstract:
Herein, an efficient and highly functional group-compatible procedure for controllable transformation of indoles by the combination of phenyliodine bis(trifluoroacetate) (PIFA) with n-Bu4NCl·H2O (TBAC) was exploited. Through controlling the amount of PIFA and TBAC from one to three equivalents, 3-chloro-indoles, 3-chloro-2-oxindoles, and 3,3-dichloro-2-oxindoles were obtained, respectively, in satisfactory to excellent yields. The advantages of the protocol include mild conditions, facile process with short reaction time, high yields, satisfactory functional group tolerance, and the use of PIFA, which is an air- and moisture-stable promoter. The mechanism studies showed that the reaction may proceed through a halonium ion species-mediated halogenation-elimination-halogenation stepwise process.
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