Copper complex with benzylamine

Crystals of Escherichia coli CAO were pre-reduced anaerobically with benzylamine, then exposed to O2. This yielded a crystal structure at 2.1 A resolution of a CAO/02/benzaldehyde complex, that gives an informative snapshot of the oxidative half-reaction (Figure ll). " The copper ion is approximately tetrahedral, with normal Cu—N bonds to the three histidine ligands and a long interaction of 2.8 3.0 A to an approximately side-on if-O2 molecule. Both O atoms of the O2 molecule take part in hydrogen bonding one is hydrogen-bonded to 02 of the TPQ... 

The use of primary amines as suitable substrates for the synthesis of 2-substituted benzimidazoles, benzoxazoles, and benzothiazoles with CuBr2 catalyst was developed by Zhou and coworkers (Scheme 8.54). A key step in this reaction is the formation of an imine intermediate via oxidative dehydrogenation of benzylamine with the copper complex and molecular oxygen [94]. 

Silica modified with different functionalities such as -NH2, -SH, diamines, and amino acids is reported to be a good support for various metals like Pd, Cu, Sc, Ru, Pt, and V for different organic transformations [52]. Recently, Likhar et al. [52] reported the A-arylation of N(H)-heterocycles and benzylamines with aryl halides and arylboronic acids using silica immobilized copper complexes (Scheme 12). 

We have used silica tethered copper complexes as reusable catalysts in the Warylation of N(H)-heterocycles and benzylamines with arylboronic acids [85] (Table 38). Warylated products were isolated in good to excellent yields, demonstrating the versatility of the protocol. Moreover the catalyst was easily recovered by simple filtration and reused for several cycles with consistent activity. 

The first reports of N-H insertion reactions of electrophilic carbene complexes date back to 1952 [497], when it was found that aniline can be N-alkylated by diazoacetophenone upon treatment of both reactants with copper. A further early report is the attempt of Nicoud and Kagan [1178] to prepare enantiomerically pure a-amino acids by copper(I) cyanide-catalyzed decomposition of a-diazoesters in the presence of chiral benzylamines. Low enantiomeric excesses (< 26% ee) were obtained, however. 

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