Asymmetric vinylogous Mannich reaction of silyloxy furans with N-tert-butanesulfinyl ketimines.
A highly regio- and diastereoselective TMSOTf promoted vinylogous Mannich reaction for the synthesis of chiral quaternary 3-aminooxindole butenolides from 2-silyloxy furans and chiral ketimines is described. The method is found to be very efficient and also provides a facile access to sterically challenging 3-aminooxindole butenolides bearing two quaternary centers in continuation. Further, the versatility of the method is demonstrated by the 1,4-addition of nucleophiles on the sterically congested butenolide substructure.
Division of Organic Chemistry, National Chemical Laboratory , Dr. Homi Bhabha Road, Pune, India 411008.
V U Bhaskara
VU
Rao
Amol P
AP
Jadhav
Dnyaneshwar
D
Garad
Ravi P
RP
Singh
D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D002384:Catalysis; D005663:Furans / Q000737:chemistry*; D007097:Imines / Q000737:chemistry*; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D009570:Nitriles / Q000737:chemistry*; D013237:Stereoisomerism; D013452:Sulfonium Compounds / Q000737:chemistry*
D005663:Furans; D007097:Imines; D007211:Indoles; C481933:N-tert-butanesulfinylimino ester; D009570:Nitriles; D013452:Sulfonium Compounds; C542835:ketimine; C004511:butenolide; D015107:4-Butyrolactone