Stereodivergent Michael addition of diphenylphosphite to α-nitroalkenes in the presence of squaramide-derived tertiary amines: an enantioselective organocatalytic reaction in supercritical carbon dioxide

Abstract

The first "green" asymmetric organocatalytic reaction in a supercritical carbon dioxide medium was elaborated. Under the proposed conditions (100 bar, 35 °C), α-nitroalkenes enantioselectively accept diphenylphosphite in the presence of bifunctional organocatalysts bearing the tertiary amino group and the squaramide fragment to afford corresponding β-nitrophosphonates in high yields and with enantioselectivities of up to 94% ee. By varying the catalyst structure it is possible to synthesize both β-nitrophosphonate enantiomers under these conditions. A significant potential of the supercritical extraction for product isolation and catalyst recovery was demonstrated. † Electronic supplementary information (ESI) available. See

Green Asymmetric Organocatalysis

“…The first organocatalytic reaction in sc‐CO 2 was reported by Kuchurov et al. in 2014 . They studied the Michael addition of diphenyl phosphite ( 159 ) to nitroalkenes 2 by using bifunctional squaramide organocatalyst C86 .…”

Prospective Symbiosis of Green Chemistry and Energetic Materials

“…[26][27][28][29] Supercritical CO 2 (scCO 2 )h as been often used in chemistry and chemical engineering as a green extracting agent of useful substances from plant and animal raw materials, [30] as an inexpensive and efficient eluent Ag lobal increasei ne nvironmental pollutiond emands the development of new "cleaner" chemical processes. Homogeneous [32] andh eterogeneous [33] catalytic or biocatalytic (enzymatic) reactions, [34][35][36] green polymerization processes, [15,16,37] and some other chemical reactions [38][39][40] were performed efficientlyi ns ub-and supercritical CO 2 . As ar esult of the favorable combinationo ft heir unique properties, ionicl iquids (ILs), dense gases, and supercritical fluids (SCFs) have gained considerable attention as suitable green chemistry media for the preparation and modification of important chemical compounds and materials.…”

“…for chromatography, [31] and as ac onvenient medium for the environmentally friendly preparationo fc hemical compounds and materials. Homogeneous [32] andh eterogeneous [33] catalytic or biocatalytic (enzymatic) reactions, [34][35][36] green polymerization processes, [15,16,37] and some other chemical reactions [38][39][40] were performed efficientlyi ns ub-and supercritical CO 2 . The global concern with regard to environmental safety in differenti ndustrial areas also affected the production of highenergy materials (HEMs).…”

Recent Advances in Asymmetric Organocatalyzed Conjugate Additions to Nitroalkenes

“…The phospha-Michael addition to nitroalkenes has been recently described using diphenylphosphite as P-centered nucleophile [ 185 ]. Thus, a tertiary amine-squaramide and a tertiary amine-thiourea have been assayed as bifunctional organocatalysts in this asymmetric reaction in a supercritical carbon dioxide medium.…”