Cu-catalyzed enantioselective conjugate addition of alkylzincs to cyclic nitroalkenes: catalytic asymmetric synthesis of cyclic alpha-substituted ketones.
An efficient and highly enantioselective (>/=92% ee) catalytic method for conjugate addition of alkylzinc reagents to cyclic nitroalkenes is reported. Reactions are promoted in the presence of 0.5-5 mol % (CuOTf)2.C6H6 and 1-10 mol % of chiral amino acid-based phosphine ligands at 0 degrees C in toluene. The Cu-catalyzed reactions can be effectively carried out with small-, medium-, and large-ring nitroalkenes. Depending on the reaction conditions used, either the nitro or the corresponding alpha-substituted ketone product can be readily accessed by the present protocol.
Luchaco-Cullis
Courtney A
CA
Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA.
Hoveyda
Amir H
AH
D000475:Alkenes / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D003510:Cyclohexanes / Q000737:chemistry; D053138:Cyclohexenes; D006844:Hydrocarbons, Cyclic / Q000138:chemical synthesis* / Q000737:chemistry; D007659:Ketones / Q000138:chemical synthesis*; D009574:Nitro Compounds / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*
D000475:Alkenes; D003510:Cyclohexanes; D053138:Cyclohexenes; D006844:Hydrocarbons, Cyclic; D007659:Ketones; D009574:Nitro Compounds; D009942:Organometallic Compounds; C052568:cyclohexene; D003300:Copper; C454811:diethylzinc