RESUMO
To gauge the feasibility of carbenoid eliminative cross-coupling for the synthesis of polyfunctional alkenes, a P-glycoprotein inhibitor containing an (E)-configured 4-chromanylidene-type trisubstituted olefin was prepared as well as its previously undescribed (Z)-isomer. Stereospecific alkene synthesis required generation of functionalized enantioenriched α-metalated carbamates [R1R2CM(O2CNi-Pr2), M = Li or Bneo], and problems associated with incorrect lithiation regioselectivity and unexpected organolithium configurational lability were encountered. Solutions to these difficulties are described together with a method for ee determination of α-carbamoyloxyboronates.
Assuntos
Alcenos/síntese química , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/antagonistas & inibidores , Alcenos/química , Alcenos/farmacologia , Estrutura Molecular , EstereoisomerismoRESUMO
The Beckmann rearrangement of ketoximes, mediated by ammonium persulfate-dimethyl sulfoxide as a reagent, has been achieved under neutral conditions. Based on the radical trapping and (18)O-labeling experiments, the transformation follows a mechanism involving a radical pathway. The scope and generality of the developed protocol has been demonstrated by 19 examples. The developed protocol and Pd-catalyzed intramolecular double C-H activation were used as key steps in the formal total synthesis of antimalarial natural product isocryptolepine.
Assuntos
Antimaláricos/síntese química , Alcaloides Indólicos/síntese química , Quinolinas/síntese química , Sulfato de Amônio/química , Catálise , Dimetil Sulfóxido/química , Sequestradores de Radicais Livres/química , Radicais Livres/química , EstereoisomerismoRESUMO
Ammonium persulfate-dimethyl sulfoxide (APS-DMSO) has been developed as an efficient and new dehydrating reagent for a convenient one-pot process for the synthesis of miscellaneous cyclic imides in high yields starting from readily available primary amines and cyclic anhydrides. A plausible radical mechanism involving DMSO has been proposed. The application of this facile one-pot imide forming process has been demonstrated for a practical synthesis of vernakalant.
