Organocatalyzed enantioselective fluorocyclizations.
Lozano O., Blessley G., Martinez del Campo T., Thompson AL., Giuffredi GT., Bettati M., Walker M., Borman R., Gouverneur V.
Enantioenriched fluorinated heterocycles can be prepared through fluorocyclizations of prochiral indoles (see scheme; Ts=tosyl, Bn=benzyl, Boc=tert-butoxycarbonyl). More than twenty examples for this cascade fluorination-cyclization, which is catalyzed by cinchona alkaloids and employs N-fluorobenzenesulfonimide as the electrophilic fluorine source have been explored, and an unprecedented catalytic asymmetric difluorocyclization has also been identified.