Design and Application of <scp><i>m</i>‐Hydroxybenzyl</scp> Alcohols in Regioselective (3 + 3) Cycloadditions of <scp>2‐Indolymethanols</scp><sup>†</sup>
Yi‐Cheng Shi, Xinyu Yan, Ping Wu, Song Jiang, Ran Xu, Wei Tan, Feng Shi
Abstract
Comprehensive Summary A new class of m ‐hydroxybenzyl alcohols has been designed as competent three‐carbon building blocks and achieved their application in 2‐indolylmethanol‐involved regioselective (3 + 3) cycloadditions under the catalysis of Brønsted acids. By this appoach, a series of indole‐fused six‐membered cycloadducts have been synthesized in overall good yields (up to 98%) with excellent regioselectivity (all >95: 5 rr), thus affording a powerful method for the construction of indole‐fused six‐membered rings. Moreover, a catalytic asymmetric version of this (3 + 3) cycloaddition has been preliminarily investigated, which revealed the potential of the reaction for constructing chiral indole‐fused six‐membered rings in an enantioselective manner. This work not only has accomplished the first design of m ‐hydroxybenzyl alcohols as competent reactants, but also represents the first application of m ‐hydroxybenzyl alcohols as three‐carbon building blocks in cycloadditions. In addition, this work provides a good example for regioselective and C3‐nucleophilic (3 + 3) cycloadditions of 2‐indolylmethanols, which will substantially enrich the chemistry of 2‐indolylmethanols.