Dual Lewis acid-Lewis base activation in enantioselective cyanation of aldehydes using acetyl cyanide and cyanoformate as cyanide sources.
Dual activation by a chiral Lewis acid and an achiral or chiral Lewis base enabled cyanation of both aromatic and aliphatic aldehydes with acetyl cyanide and ethyl cyanoformate to provide direct access to O-acetylated and O-alkoxycarbonylated cyanohydrins, respectively, under mild conditions. With a combination of a Ti-salen catalyst and Et3N, benzaldehyde was converted to the O-acetylated cyanohydrin with 94% ee within 10 h at -40 degrees C in 89% isolated yield.
Lundgren
Stina
S
Department of Chemistry, Organic Chemistry, Royal Institute of Technology, SE 100 44 Stockholm, Sweden.
Wingstrand
Erica
E
Penhoat
Maël
M
Moberg
Christina
C
D000447:Aldehydes / Q000138:chemical synthesis* / Q000737:chemistry; D003486:Cyanides / Q000737:chemistry*; D015394:Molecular Structure; D009570:Nitriles / Q000138:chemical synthesis / Q000737:chemistry*; D013237:Stereoisomerism
D000447:Aldehydes; D003486:Cyanides; D009570:Nitriles