Fluorine-Activated and -Directed Allene Cycloadditions with Nitrile Oxides and Imine Oxides: Synthesis of Ring-Fluorinated Isoxazole Derivatives
Kohei Fuchibe, K SAKON, Kyosuke Suto, R. Eto, Sho Nakazono, Junji Ichikawa
Abstract
In this study, 1,1-difluoroallenes underwent a regioselective [2+3] cycloaddition with nitrile oxides and imine oxides in the presence of a AuCl catalyst. ( E )-4-Alkylidene-5,5-difluoroisoxazolines and -isoxazolidines were obtained in regioselective and diastereoselective manners by employing aurated difluoroallylic cation intermediates. The synthesized 5,5-difluoroisoxazolines were readily aromatized through dehydrofluorination or allylic fluorine substitution to provide 5-fluoroisoxazoles.
Topics & Concepts
ChemistryRegioselectivityNitrileAlleneIsoxazoleCycloadditionImineAllylic rearrangementRing (chemistry)FluorineMedicinal chemistryOrganic chemistryCatalysisFluorine in Organic ChemistryCyclopropane Reaction MechanismsSynthesis and Catalytic Reactions