AZOMETHINE YLIDE CYCLOADDITION/REDUCTIVE HETEROCYCLIZATION APPROACH TO OXINDOLE ALKALOIDS: ASYMMETRIC SYNTHESIS OF (-)-HORSFILINE

The intermolecular [3 + 2] annulation of azomethine ylides with 2(2-nitrophenyl)acrylate dienophiles followed by reductive heterocyclization affords the spiro(indole-pyrrolidine) ring system. Hence, this enable us to accomplish a concise and highly enantioselective synthesis of ( 12)-horsfiline 1, based on chiral auxiliary-directed \u3c0-face discrimination in the 1,3-dipolar cycloaddition of (1S,2R)-2-phenyl-1-cyclohexyl ester 4f with N-methylazomethine ylide

Camphor-based oxazaphospholanes as chiral templates for the enantioselective synthesis of a-chlorophosphonic acids

Constrained camphor-derived oxazaphospholanes have provided an efficient entry for the preparation of enantiomerically enriched \u3b1-chlorophosphonic acids

Chiral atropisomeric five-membered biheteroaromatic diphosphines: new ligands of the bibenzimidazole and biindole series

Two new chiral atropisomeric biheteroaromatic diphosphines are described: 2,2\u2032-bis(diphenylphosphino)-1,1\u2032-bibenzimidazole (3a) and 3,3\u2032-dimethyl-1,1\u2032-bis(diphenylphosphino)-2,2\u2032-biindole (4a). Structural characterization is given and configurational stability at room temperature demonstrated. The oxidation potential was recognized as a good tool to evaluate the electronic availability of the phosphorus atom in the series of biheteroaromatic diphosphines. Its value increases parallel to the electronic demand of the heterocyclic system and also depends on the position of the diphenylphosphino group