Ag-catalyzed asymmetric mannich reactions of enol ethers with aryl, alkyl, alkenyl, and alkynyl imines.
An efficient catalytic and enantioselective method (up to >98% ee) for Mannich reactions between trimethylsilyl enol ethers derived from acetone and acetophenone and aryl, alkenyl, alkynyl, and alkyl imines is disclosed. A large variety of beta-amino ketones can be synthesized in the presence of 1-5 mol % AgOAc and an inexpensive and readily available amino acid-derived phosphine. All Ag-catalyzed asymmetric Mannich reactions can be run in undistilled THF and air. The o-anisyl activating groups of product amines can be removed in >70% isolated yield through a single vessel operation. The synthetic utility of the catalytic asymmetric method is illustrated by a four-pot synthesis of optically pure alkaloid (-)-sedamine.
Josephsohn
Nathan S
NS
Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA.
Snapper
Marc L
ML
Hoveyda
Amir H
AH
D002384:Catalysis; D003500:Cyclization; D004987:Ethers / Q000737:chemistry; D007097:Imines / Q000737:chemistry*; D008352:Mannich Bases / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D012834:Silver / Q000737:chemistry*; D014297:Trimethylsilyl Compounds / Q000737:chemistry*
D004987:Ethers; D007097:Imines; D008352:Mannich Bases; D014297:Trimethylsilyl Compounds; D012834:Silver