RESUMO
We examined the catalytic enantioselective fluorination of 3-(2-arylacetyl)-2-thiazolidinones 1 with N-fluorobenzenesulfonimide (NFSI) by DBFOX-Ph/metal complexes under a variety of conditions. After optimization of the metal salts, solvents and additives, we found that the fluoro-2-thiazolidinones 2 were obtained in good to high yields with moderate to good enantioselectivities (up to 78% ee) when the reaction was carried out in the presence of DBFOX-Ph (11 mol%), Ni(ClO(4))(2).6H(2)O (10 mol%) and 2,6-lutidine (0 or 1.0 equiv) in CH(2)Cl(2).
RESUMO
The first catalytic enantioselective hydroxylation reaction of both 3-aryl and 3-alkyl-2-oxindoles using the DBFOX-Zn(II) complex, leading to pharmaceutically important chiral 3-hydroxy-2-oxindoles was described. The structure of oxidant was found to play an important role to increase the enantioselectivity. The methodology has successfully applied to the highly enantioselective hydroxylation of beta-keto esters using the DBFOX-Ni(II) complex.
Assuntos
Ésteres/síntese química , Indóis/síntese química , Cetonas/síntese química , Zinco/química , Catálise , Ésteres/química , Compostos Heterocíclicos com 3 Anéis/química , Hidroxilação , Indóis/química , Cetonas/química , Ligantes , Estrutura Molecular , Níquel/química , Oxazóis/química , Oxindóis , EstereoisomerismoRESUMO
We have employed a cinchona alkaloid/Selectfluor-mediated enantioselective fluorination of the oxindole 2 to achieve the first enantioslective synthesis of BMS-204352 (MaxiPost, S-1), an effective opener of maxi-K channels. Fluorination occurred to produce S-1 with 84% ee using the bis-cinchona alkaloid (DHQ)(2)AQN. Recrystallization produced enantiomerically pure (>99% ee) product. Quinidine-mediated fluorination of 2 gave the (R)-antipode of 1 with 68% ee.
