Organocatalytic enantioselective Michael addition of malononitrile to nitroolefins catalyzed by bifunctional thiourea

Abstract

A novel enantioselective Michael addition of malononitrile to trans-β-nitroolefins in the presence of bifunctional amine thiourea organocatalyst is developed. The Michael reaction catalyzed by amine thioureas containing both central and axial chiral elements proceeded smoothly and provided the desired adducts with high yields (up to 96% yield) and moderate enantioselectivities (up to 83% enantiomeric excess).

Chiral Thioureas—Preparation and Significance in Asymmetric Synthesis and Medicinal Chemistry

“…Schreiner and co-workers chose an imidazole-based catalyst (in cooperation with Brønsted acids) as the best one for cyanosilylation of various aldehydes [161]. An axially-chiral binaphthyl-derived amine was used for the synthesis of thioureas which catalyzed stereoselective Michael addition of 2,4-pentanodione and malononitrile to nitroolefins [162,163]. A variety of thiourea organocatalysts based on chiral diaminocyclohexane skeleton have been prepared.…”

An Efficient Solvent Free Microwave Assisted MgFe2O4 Magnetic Nanoparticles Catalyzed Green Protocol Towards Michael Addition

“…An extensive study has been focused in the design and development of catalysts, which will result in high selectivity, mild reaction conditions and sufficient tolerance to a wide range of nucleophilic substrates. During the past decades more efficient and milder catalysts including 1,5,7-triazabicyclo[4,4,0]dec-5ene (TBD) [17], natural phosphate doped catalyst [18], SmI 3 [19], imidazolium ionic liquid [20], bifunctional organocatalyst [21] have been developed in this area of research. There have been few reports on Michael reaction catalyzed by K 2 CO 3 in an organic solvent in the presence of water [22], surfactants [23] and under phase transfer catalyst conditions [24][25][26].…”

The mechanism investigation of the imidazolidinone catalyzed five‐membered ring synthesis reaction

“…In the last few years, organocatalytic Michael reactions in organic synthesis has become an increasingly active area . Since MacMillan's group prepared the first‐generation imidazolidinone ((2S,5S)‐5‐benzyl‐2‐dimethyl‐3‐methylimidazolidin‐4‐one) and developed the second‐generation tert‐butyl imidazolidinone ((2S,5S)‐5‐benzy‐2‐tert‐butyl‐3‐methylimidazolidin‐4‐one) based on a study of the catalyst's molecular model, the profound efficiency and applicability of imidazolidinone catalysts in organic synthesis have been established .…”