Helical Multi‐Coordination Anion‐Binding Catalysts for the Highly Enantioselective Dearomatization of Pyrylium Derivatives

CApTive lock‐key model: Oxygen heterocycles were synthesized in high enantioselectivities from pyrylium derivatives by embracing a multi‐coordination approach with helical anion‐binding tetrakistriazole catalysts. New insights into the hydrogen‐donor ability and key binding interactions suggest the formation of a high‐order host:guest complex.

Abstract

A general and highly enantioselective synthesis of oxygen heterocycles from readily available in situ generated pyrylium derivatives has been realized by embracing a multi‐coordination approach with helical anion‐binding tetrakistriazole catalysts. The high activity of the tetrakistriazole (TetraTri) catalysts, with distinct confined anion‐binding pockets, allows for remarkably low catalyst loadings (down to 0.05 mol %), while providing a simple access to chiral chromanones and dihydropyrones in high enantioselectivities (up to 98:2 e.r.). Moreover, experimental and theoretical studies provide new insights into the hydrogen‐donor ability and key binding interactions of the TetraTri catalysts and its host:guest complexes, suggesting the formation of a 1:3 species.

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