Chiral cyclopropenimine-catalyzed enantioselective Michael reactions of phenol and benzofuran-derived α,β-unsaturated pyrazolamides with benzophenone-imine of glycine esters

• Ya Bai,
• Xue-Ying Wang,
• Si-Kai Zhu,
• Yan-Ting Shen,
• Sheng-Yong Zhang and
• Ping-An Wang

Beilstein J. Org. Chem. 2026, 22, 888–896, doi:10.3762/bjoc.22.69

• adjacent stereocenters, which was obtained from in-situ acidic hydrolysis and lactamization of the corresponding Michael product. Keywords: α,β-unsaturated pyrazolamide; chiral cyclopropenimine; glutamic acid; lactamization; Michael addition; Introduction Phenols and benzofurans are feedstock chemicals

• ion pair A, which attacks β-substituted α,β-unsaturated pyrazolamide 5a to provide transition state B. Transition state B may be stabilized through an H-bonding interaction network between the two substrates and CSB-1. Additionally, π–π stacking between the two phenyl groups of 2a and 5a may also

• benzofuran-derived pyrazolamides 5m–q were synthesized through DBU-mediated cyclocondensation of 2-hydroxybenzaldehydes with 4-bromocrotonates to afford (E)-2-benzofuranyl-3-acrylates followed hydrolysis and coupling with 3,5-dimethyl-1H-pyrazole (Scheme 2b) [12]. Initially, the Michael reaction between α,β