102014-84-6Relevant articles and documents
Direct Catalytic Asymmetric Aldol Reaction of an α-Azido Amide
Weidner, Karin,Sun, Zhongdong,Kumagai, Naoya,Shibasaki, Masakatsu
, p. 6236 - 6240 (2015)
A direct aldol reaction of an α-azido 7-azaindolinylamide, promoted by a Cu-based cooperative catalyst, is documented. Aromatic aldehydes bearing an ortho substituent exhibited diastereodivergency depending on the nature of the chiral ligands used. Smooth reactions with ynals highlighted the broad substrate scope. A vicinal azido alcohol unit in the product allowed direct access to the corresponding aziridine and facile hydrolysis of the 7-azaindolinylamide moiety furnished enantioenriched β-hydroxy-α-azido carboxylic acid derivatives.
α-Halo Amides as Competent Latent Enolates: Direct Catalytic Asymmetric Mannich-Type Reaction
Sun, Bo,Balaji, Pandur Venkatesan,Kumagai, Naoya,Shibasaki, Masakatsu
, p. 8295 - 8301 (2017)
α-Halogenated carbonyl compounds are susceptible to dehalogenation and thus largely neglected as enolate precursors in catalytic enantioselective C-C bond-forming reactions. By merging the increased stability of the α-C-halogen bond of amides and the direct enolization methodology of the designed amide, we explored a direct catalytic asymmetric Mannich-type reaction of α-halo 7-azaindoline amides with N-carbamoyl imines. All α-halo substituents, α-F, -Cl, -Br, -I amides, were tolerated to provide the Mannich-adducts in a highly stereoselective manner without undesirable dehalogenation. The diastereoselectivity switched intriguingly depending on the substitution pattern of the aromatic imines, which is ascribed to stereochemical differentiation based on the open transition-state model. Functional group interconversion of the 7-azaindoline amide moiety of the Mannich-adducts and further elaboration into a diamide without dehalogenation highlight the synthetic utility of the present protocol for accessing enantioenriched halogenated chemical entities.
