Amine Functionalization through Sequential Quinone‐Catalyzed Oxidation/Nucleophilic Addition

Abstract

A simple and efficient method for the synthesis of α‐branched amines through formal oxidative C–H functionalization is reported. A commercially available quinone organocatalyst is employed to promote the aerobic oxidation of primary amines to the corresponding N‐protected imines, which are then trapped in situ with an appropriate nucleophile to give access to versatile functionalized amines in good to excellent yields (70–90 %).

Quinone-catalyzed oxidative deformylation: synthesis of imines from amino alcohols

“…With this plan in mind, we first explored the ability of several quinone catalysts to promote the deformylation of 2-phenylglycinol ( 1a ) to deliver N -PMP imine 7a ( Table 1 ). We selected quinone catalysts ( 2a − c ) that have previously been utilized in amine oxidation reactions [ 21 , 32 , 40 – 41 ], and began with reaction conditions similar to those developed for our quinone-catalyzed oxidative decarboxylation chemistry [ 32 ]. To our delight, the desired deformylation product 7a was formed in 63% yield when catalyst 2a was employed ( Table 1 , entry 1).…”

Asymmetric Transfer Hydrogenations of β-Enamine Cyanide with Chiral Ammonia Borane

“…95～96 ℃; (S)-3-苯基-3-[(4-甲氧基苯基)氨基]丙腈(3d) [21,25] : 黄色油状物, 0.0742 g, 产率 98%, 90% ee. (S)-3-( 对 甲 苯 基 )-3-[(4-甲 氧 基 苯 基 ) 氨 基 ] 丙 腈 (3g) [28] : 黄色油状物, 0.0662 g, 产率 83%, 91% ee. [28] : 黄色油状物, 0.0500 g, 产率 87%, 91% ee.…”

“…(S)-3-( 对 甲 苯 基 )-3-[(4-甲 氧 基 苯 基 ) 氨 基 ] 丙 腈 (3g) [28] : 黄色油状物, 0.0662 g, 产率 83%, 91% ee. [28] : 黄色油状物, 0.0500 g, 产率 87%, 91% ee. [28] : 黄色油状物, 0.0841 g, 产率 91%, 91% ee.…”

“…[28] : 黄色油状物, 0.0841 g, 产率 91%, 91% ee. [28] : 黄色油状物, 0.0502 g, 产率 94%, 91% ee. (S)-3-苯基-3-(苄基氨基)丙腈(3o) [30] : 黄色油状物, 0.0341 g, 产率 48%, 61% ee.…”

Homologation of α-aryl amino acids through quinone-catalyzed decarboxylation/Mukaiyama–Mannich addition

“…Quinone 2 was selected for initial studies because of it’s established ability to enable the aerobic oxidation of amines. 17 Valine, phenylalanine, serine and phenylglycine were first tested (entries 1–4, only phenylglycine results shown) with entry 4 providing initial conditions to promote imine formation for only the α-aryl amino acid. The addition of triethylamine as a base resulted in a slight improvement in reaction efficiency (entry 5, 42% yield) that was furthered by elevation of the reaction temperature (entry 6, 68% yield).…”