Cu-catalyzed asymmetric allylic alkylations of aromatic and aliphatic phosphates with alkylzinc reagents. An effective method for enantioselective synthesis of tertiary and quaternary carbons.
Efficient enantioselective Cu-catalyzed allylic alkylations of aromatic and aliphatic allylic phosphates bearing di- and trisubstituted olefins are disclosed. Enantioselective C-C bond forming reactions are promoted in the presence of 10 mol % readily available chiral amino acid-based ligand (5 steps, 40% overall yield synthesis) and 5 mol % (CuOTf)2 x C6H6. Reactions deliver tertiary and quaternary stereogenic carbon centers regioselectively and in 78-96% ee. Data regarding the effect of variations in ligand structure on the efficiency and enantioselectivity of the alkylation process, as well as a mechanistic working model, are presented. The suggested model involves a dual role for the chiral Cu complex: association of the Cu(I) center to the olefin is facilitated by a two-point binding between the carbonyl of the ligand's amide terminus and the P=O of the substrate.
Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA.
Monica A
MA
Kacprzynski
Amir H
AH
Hoveyda
D000478:Alkylation; D000498:Allyl Compounds / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D006838:Hydrocarbons / Q000138:chemical synthesis* / Q000737:chemistry; D006841:Hydrocarbons, Aromatic / Q000138:chemical synthesis* / Q000737:chemistry; D009942:Organometallic Compounds / Q000737:chemistry; D010755:Organophosphates / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
D000498:Allyl Compounds; D006838:Hydrocarbons; D006841:Hydrocarbons, Aromatic; D009942:Organometallic Compounds; D010755:Organophosphates; D003300:Copper; D015032:Zinc