Enantioselective Organocatalytic Michael Reaction Of α,β-Unsaturated Ketones And Diphenylphosphine Oxides/2-Oxindoles

Within this paper, new methods for asymmetric conjugate addition of diphenylphosphine oxides and oxindoles to enone have been developed respectively, by novel organocatalysts.The asymmetric Michael reaction of diphenylphosphine oxides and enones was investigated for the first time, employing organocatalysts consisting of 1, 2-diaminocyclohexane and 9-amino-9-deoxy-epicinchona alkaloid. The effects of catalyst, solvent, temperature and additives in the reaction system on the Michael addition were investigated. Under the optimized reaction conditions, the nucleophilies (diphenylphosphine oxide) reacted with a series of enone smoothly to afford the 1,4-adducts in excellent yields (up to 97%) and enantioselectivities (up to 98%). Moreover, the organocatalytic enantioselective construction of all-carbon quaternary stereocenters has been achieved which is an important yet challenging task in asymmetric synthesis.The enantioselective Michael reaction of 3-substituted oxindoles and enones was investigated for the first time. The novel transformations exhibited high diastereoselectivities(up to 98:2), and the adducts bearing adjacent quaternary and tertiary chiral centers were generally obtained in good to excellent enantioselectivities (up to 99% ee).