Helical chiral 2-aminopyridinium ions: a new class of hydrogen bond donor catalysts.
Helical chiral 2-aminopyridinium ions were designed as a significantly more acidic (active) dual hydrogen-bonding catalyst than commonly used (thio)urea-based systems. The helicene framework was specifically utilized to position an inherently chiral barrier on the hydrogen-bonding side of the catalyst. The catalyst reactivity and enantioselectivity were successfully demonstrated in additions of 4,7-dihydroindoles to nitroalkenes (0.5-2 mol % catalyst loadings, up to 98:2 er).
Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, Florida 33146-0431, USA. n.takenaka@miami.edu
Norito
N
Takenaka
Jinshui
J
Chen
Burjor
B
Captain
Robindro Singh
RS
Sarangthem
Appayee
A
Chandrakumar
D000631:Aminopyridines / Q000737:chemistry*; D001372:Aza Compounds / Q000138:chemical synthesis / Q000737:chemistry; D002384:Catalysis; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D007477:Ions / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D013237:Stereoisomerism
D000631:Aminopyridines; D001372:Aza Compounds; D007477:Ions; C032439:alpha-aminopyridine