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Catalytic Enantioselective (4+4) Annulation of o-Hydroxybenzyl Alcohols with 4-Indolylmethanols
Wen-Yu Luan1, Ting-Yu Fang1, Yu-Fei Wu1
1School of Chemistry and Materials Science, Research Center of Chiral Functional Heterocycles, Jiangsu Normal University, Xuzhou 221116, China.
Abstract:
A catalytic enantioselective (4+4) annulation of o-hydroxybenzyl alcohols with 4-indolylmethanols has been established under chiral phosphoric acid (CPA) catalysis. By this protocol, a variety of chiral indole-based eight-membered heterocycles are prepared in generally good yields with high enantioselectivities (up to 89% yield, up to 99:1 er). This reaction realizes the first catalytic enantioselective (4+4) annulation of o-hydroxybenzyl alcohols and represents the first catalytic enantioselective (4+4) annulation of 4-indolylmethanols, which will enrich the chemistry of o-hydroxybenzyl alcohols and indolylmethanols. Furthermore, this protocol will offer a new strategy for synthesizing enantioenriched indole-based eight-membered heterocycles.
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