Practical and highly enantioselective synthesis of beta-alkynyl-beta-amino esters through Ag-catalyzed asymmetric mannich reactions of silylketene acetals and alkynyl imines.
[reaction: see text] A readily available iso-leucine-based phosphine ligand is used to promote Ag-catalyzed Mannich reactions between silylketene acetals and various alkynyl imines. Reactions can be effected in the presence of 5 mol % catalyst, without the need for rigorous exclusion of air, and with commercially available solvents (without purification) to afford the desired beta-alkynyl-beta-amino esters in 84-94% ee and 61-91% isolated yield.
Josephsohn
Nathan S
NS
Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA.
Carswell
Emma L
EL
Snapper
Marc L
ML
Hoveyda
Amir H
AH
D000080:Acetals / Q000737:chemistry; D000480:Alkynes / Q000138:chemical synthesis* / Q000737:chemistry*; D000596:Amino Acids / Q000138:chemical synthesis*; D002384:Catalysis; D004952:Esters; D007097:Imines / Q000737:chemistry; D007202:Indicators and Reagents; D015394:Molecular Structure; D012821:Silanes / Q000737:chemistry; D012834:Silver / Q000737:chemistry; D013237:Stereoisomerism
D000080:Acetals; D000480:Alkynes; D000596:Amino Acids; D004952:Esters; D007097:Imines; D007202:Indicators and Reagents; D012821:Silanes; D012834:Silver