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    Enantioselective installation of quaternary centers in cyclic oxonitriles
    (Wiley-VCH Verlag, 2015) Güneş, Yakup; Arçelik, Nejat; Şahin, Ertan; Fleming, Fraser F.; Altundaş, Ramazan
    Quaternary centers are rapidly and selectively installed in a series of seven-membered and bridged cyclic oxonitriles through conjugate addition of an alkoxide to chloroalkenenitriles, followed by a Claisen rearrangement. Using this strategy, the stereogenic information of the carbinol in secondary allylic alcohols is transferred to the newly generated quaternary center. Experimentally, the sequence rapidly gives alkyl cyanocycloheptanones and bicycloalkanonecarbonitriles in good yield and with high selectivity, in a single synthetic operation.
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    Enantioselective synthesis of cyclic, quaternary oxonitriles
    (American Chemical Society, 2010) Güneş, Yakup; Polat, Muhammed Fatih; Şahin, Ertan; Fleming, Fraser F.; Altundaş, Ramazan
    Quaternary oxonitriles are stereoselectively generated from the union of five-, six-, and seven-membered 2-chloroalkenecarbonitriles with chiral alcohols via a Claisen rearrangement. The strategy rests on a new conjugate addition-elimination of allylic alkoxides to 2-chlorocycloalkenecarbonitriles to afford substituted 2-alkoxyalkenenitriles. Subsequent thermolysis unmasks a cyclic oxonitrile while selectively forming a new quaternary center with enantiomeric ratios typically greater than 9:1. The overall alkylation strategy addresses the challenge of enantioselectively generating hindered, quaternary centers while simultaneously installing ketone, nitrile, and olefin functionalities.