Cinchona based squaramide catalysed enantioselective Michael addition of α-nitrophosphonates to aryl acrylates: enantioselective synthesis of quaternary α-aminophosphonates
摘要:
Several cinchona based squaramide catalysts were applied to the asymmetric Michael addition of alpha-nitroethylphosphonates to acrylic acid aryl esters, resulting in high yields and enantioselectivities. The absolute configuration of one of the quaternary alpha-nitrophosphonate adducts was deduced from its experimental and calculated CD spectra. The adducts were reduced to their cyclic aminophosphonates by catalytic hydrogenation. (C) 2013 Elsevier Ltd. All rights reserved.
GRAPHICAL ABSTRACT ABSTRACT Three types of chiral catalysts: a chincona-based squaramide, TADDOL and a group of sugar-based crown ethers were applied to the asymmetric Michael addition of diethyl (cyanofluoromethyl)phosphonate to diverse Michael acceptors. Two of the crown ether catalysts resulted in high yields and enantioselectivities with trans-β-nitostyrene as in case of the chincona-based squaramide
The use of arylacrylates in the Baylis-Hillmanreaction is reported. In contrast to their alkyl counterparts these acrylates react very rapidly with aldehydes, often yielding cyclic products arising from reaction of the initial adduct with a second molecule of aldehyde.
Palladium-Catalyzed N-Alkenylation of N-Aryl Phosphoramidates with Alkenes
作者:Yu-An Li、Ge Wu、Jia Li
DOI:10.3390/molecules28114466
日期:——
Versatile and concise Pd-catalyzed oxidative N-alkenylation of N-aryl phosphoramidates with alkenes is described in this study, a reaction that is of great significance but surprisingly unexploited. The transformation proceeds under mild reaction conditions, using O2 as a green oxidant and TBAB as an effective additive. An efficient catalytic system allows a variety of drug-related substrates to participate