Indolylmethanols as <scp>C4</scp> Synthons for the Asymmetric Synthesis of Indole‐Fused Spiro Compounds

Abstract

Comprehensive Summary A novel asymmetric [4+2] cycloaddition of indolylmethanols with aurones via chiral phosphoric acid (CPA) catalysis has been established. Enantioenriched indole‐fused spiro compounds were obtained in good yields (60%–89%) with excellent diastereoselectivities (up to &gt;19 : 1 dr) and enantioselectivities (83%–99% ee) with broad substrate scope. This approach not only enabled the first catalytic asymmetric [4+2] cycloaddition of 3‐methyl‐2‐indolylmethanols, but also represented different reactivity from traditional indolylmethanol chemistry. In this reaction, 3‐methyl‐2‐indolylmethanols behaved as C4 synthons rather than C3 synthons.

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