Copper complexes 5-amino imines

In 2004, Kobayashi et al. introduced enecarbamates as nucleophiles to asymmetric catalysis [48], The addition of enecarbamates to imines in the presence of a chiral copper complex provides access to P-amino imines which can be hydrolyzed to the corresponding p-amino carbonyl compounds [49],... 

Kobayashi and coworkers pioneered the use of enamides or enecarbamates as nucleophiles in enantioselective reactions with either glyoxylates or glyoxylate derived imines catalyzed by chiral copper complexes [65]. The reaction using enamides or enecarbamates as nucleophilic components, namely, the aza ene reaction, with imines provides P amino imines that can be readily transformed into... 

In analogy with the enantioselective carbonyl-ene reactions (Chapter 2, Section 2.11), an attractive but much less well precedented alternative to imine allylations is enantioselective imino-ene reactions. The first such example was reported by Lectka, who found that the Tol-BINAP copper complex 216 promoted the addition of unactivated alkenes to N-tosyl imine 110 (Equation 27) [31, 153, 173]. This transformation provided the homoallylic a-amino acid 270 in 90 % yield and 99 % ee. 

Bovine serum amine oxidase (BSAO) is a copper-containing amine oxidase which utilizes a covalently bound 2,4,5-trihydroxyphenylalanine quinone (TPQ) cofactor in the two-electron oxidation of a broad spectrum of primary amines [99]. The oxidation is thought to proceed via the formation of an iminium complex between the oxidized form of the cofactor and the primary amine (1 in Scheme 10.4). The substrate imine undergoes deprotonation to form product imine, which, after hydrolysis, releases aldehyde product and reduced cofactor [100]. Proton transfer is either partially or largely rate-limiting for the oxidation of benzylamines, as evidenced by a large deuterium isotope effect at the methylene adjacent to the amino group [36, 101, 102]. 

Carretero and coworkers have successfully employed a copper(I)-Fesulphos complex as a Lewis acid for enantioselective Mannich-type reactions of N-sulfonyl imines [43]. A combination of [151 CuBr]2 and AgCl04 does efficiently catalyze the addition of silyl enol ethers of ketones, esters, and thioesters (150) to N-(2-thienyl)sulfonyl aldimines (Scheme 17.30). The corresponding P-amino carbonyl derivatives (152) were isolated in good yields with generally good enan-tioselectivity. 

Copper-bis oxazolidinone complex catalyzed the addition of alkyl and aromatic alkynes to the imine formed by the reaction of ethyl glyoxylate and p-anisidine, providing an easy access to chiral p,Y-alkynyl a-amino acids in good yields (61-80%) and enantioselectivities (66-74%) [38]. The presence of the two phenyl groups in the ligand was found to be crucial in the enantioselectivity enhancement and reduction of the reaction time, with aryl alkynes providing better results than alkyl acetylene derivatives [39]. Another type of Cu(II)-pybox complex led to excellent results in terms of enantioselectivities (28-93% yield, 81-98% ee) in the reaction of aliphatic alkynes with aldehydes and amines [40]. 

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