1239488-19-7Relevant articles and documents
A Chemoselective α-Oxytriflation Enables the Direct Asymmetric Arylation of Amides
Li, Jing,Berger, Martin,Zawodny, Wojciech,Simaan, Marwan,Maulide, Nuno
supporting information, p. 1883 - 1891 (2019/07/08)
Until recently, the direct oxidative oxysulfonylation of carbonyl compounds was limited to ketones. Here, we report the first direct oxytriflation of simple, non-activated amides. Amide umpolung with triflic anhydride and pyridine-N-oxide in the absence of external nucleophiles directly leads to the formation of reactive α-triflates in a single step, which provides a platform for the deployment of valuable downstream α-functionalization reactions. The utility of this method was demonstrated by in situ clean conversion to their corresponding bromides, as desirable starting materials for nickel-catalyzed deracemizing enantioselective arylation. This approach not only enables a telescoped asymmetric arylation of unsubstituted amides but also extends its scope because of the broad chemoselectivity and functional group tolerance of the method. Amides bearing a functional group in α-position are found in many natural products and drugs. The direct α-functionalization of amides is one of the most popular approaches to access these moieties. Classically, the α-functionalization of amides has been dominated by enolate chemistry; however, carboxamides are among the least C-H acidic carbonyl derivatives, and the presence of further carbonyl or carboxyl groups (such as esters and ketones) is therefore not usually tolerated. Here, we report the first direct α-oxytriflation of simple, non-activated amides using triflic anhydride and pyridine-N-oxide in the absence of external nucleophiles, which provides a platform for the deployment of valuable downstream α-functionalization reactions. The utility of this method was demonstrated by in situ clean conversion to the corresponding bromides, which are valuable starting materials for nickel-catalyzed deracemizing enantioselective arylation. A direct and chemoselective α-oxytriflation of simple and non-activated amides has been developed. This approach provides a platform for the development of valuable downstream α-functionalization reactions of amides. Furthermore, the combination of α-oxytriflation of amides and nickel-catalyzed Suzuki reaction provides an efficient approach for direct asymmetric α-arylation of simple amides.
Asymmetric suzuki cross-couplings of activated secondary alkyl electrophiles: Arylations of racemic α-chloroamides
Lundin, Pamela M.,Fu, Gregory C.
supporting information; experimental part, p. 11027 - 11029 (2010/09/17)
A nickel-catalyzed stereoconvergent method for the enantioselective Suzuki arylation of racemic α-chloroamides has been developed. This process provides a unique example of an asymmetric arylation of an α-haloamide, an enantioselective arylation of an α-chlorocarbonyl compound, and an asymmetric Suzuki reaction with an activated alkyl electrophile or an arylboron reagent. The method is also applicable to the corresponding enantioselective cross-coupling of α-bromoamides. The coupling products can be transformed without racemization into enantioenriched α-arylcarboxylic acids and primary alcohols. A modest kinetic resolution of the α-chloroamide was observed; a mechanistic study indicated that the selectivity may reflect discrimination by the chiral catalyst of the two enantiomeric α-chloroamides in an irreversible oxidative-addition process.
