Tuning the Basicity of a Metal‐Templated Brønsted Base to Facilitate the Enantioselective Sulfa‐Michael Addition of Aliphatic Thiols to α,β‐Unsaturated <i>N</i>‐Acylpyrazoles

Abstract

Abstract The enantioselective addition of aliphatic thiols to α,β‐unsaturated N ‐acylpyrazoles catalyzed by a bis‐cyclometalated iridium(III) complex with fine‐tuned Brønsted basicity was investigated. Good to excellent yields (71–99 %) and enantioselectivities (86–98 % ee ) were achieved at catalyst loadings of 0.2–2.5 mol‐%. In this metal‐templated catalyst design, the metal serves as a structural center and the catalysis is executed by the organic ligand sphere through a combination of proton transfer, hydrogen‐bond formation, and electrostatic interactions.