A copper-catalyzed amino lactonization of unsaturated carboxylic acids has been achieved as well as the analogous intermolecular three-component amino oxygenation of olefins. The transformation features mild conditions and a remarkably broad substrate scope, offering a novel and efficient approach to construct a wide range of amino lactones as well as 1,2-amino alcohol derivatives. Mechanistic studies suggest that the reaction proceeds via a distinctive O-benzoylhydroxylamine-promoted electrophilic amination of alkenes.
The chemo-, regio-, diastereo-, and enantioselective 1,2-oxyamination of alkenes using selenium(II/IV) catalysis with a chiral diselenide catalyst is reported. This method uses Ntosylamides to generate oxazoline products that are useful both as protected 1,2-amino alcohol motifs and as chiral ligands. The reaction proceeds in good yields with excellent enantio-and diastereoselectivity for a variety of alkenes and pendant functional groups such as sulfonamides, alkyl halides, and glycol-protected ketones. Furthermore, the rapid generation of oxazoline products is demonstrated in the expeditious assembly of chiral PHOX ligands as well as diversely protected amino alcohols.
A three-component reaction for 1,2-amino oxygenation of 1,3-dienes has been achieved using Oacyl hydroxylamines and carboxylic acids. The reaction occurs through copper-catalyzed amination of olefins followed by nucleophilic addition of carboxylic acids, offering high levels of chemo-, regio-, and site-selectivity. The method is effective for both terminal and internal 1,3dienes, including those bearing multiple, unsymmetrical substituents. The amino oxygenation conditions also exhibited remarkable selectivity toward 1,3-dienes over alkenes, good tolerance of sensitive functional groups, and reliable scalability.
Copper-catalyzed alkene amino oxygenation reactions using O-acylhydroxylamines have been achieved for a rapid and modular access to diverse 1,2-amino oxygen-containing molecules. This transformation is applicable to the use of alcohols, carbonyls, oximes and thio-carboxylic acids as nucleophiles on both terminal and internal alkenes. Mild reaction conditions tolerate a wide range of functional groups, including ether, ester, amide, carbamate, and halide. The reaction protocol allows for starting with free amines as the precursor of O-benzoylhydroxylamines to eliminate their isolation and purification, contributing to broader synthetic utilities. Mechanistic investigations reveal the amino oxygenation reactions may involve distinct pathways, depending on different oxygen nucleophiles.
SummaryThis paper reports a novel approach for the direct and facile synthesis of 1,2-oxyamino moieties via an intermolecular copper-catalyzed oxyamination of olefins. This strategy utilizes O-benzoylhydroxylamines as an electrophilic amine source and carboxylic acids as a nucleophilic oxygen source to achieve a modular difunctionalization of olefins. The reaction proceeded in a regioselective manner with moderate to good yields, exhibiting a broad scope of carboxylic acid, amine, and olefin substrates.
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