Copper complexes amination with

The copper salt (or copper complex) reacts with Me2PhSi-B(Pin) to deliver the corresponding L-Cu(l)-silane. In parallel, the chiral amine forms the iminium intermediate V with the a,p-unsaturated aldehyde. Next, the catalytic cycles merge and the L-Cu-silane complex stereoselectively reacts with the chiral iminium intermediate V via a possible intermediate W to form a C-Si bond in intermediate X. Subsequent hydrolysis of iminium ion X gives the corresponding P-silyl aldehyde product as weU as regenerate the Cu(I)-silane and the chiral catalyst L37 [115]. 

Crystal stmctures of complexes of copper(II) with aromatic amine ligands and -amino acids " " and dipeptides" have been published. The stmctures of mixed ligand-copper complexes of L-tryptophan in combination with 1,10-phenanthroline and 2,2 -bipyridine and L-tyrosine in combination with 2,2 -bipyridine are shown in Figure 3.2. Note the subtle difference between the orientation of the indole ring in the two 1,10-phenanthroline complexes. The distance between the two... 

Hydantoin itself can be detected ia small concentrations ia the presence of other NH-containing compounds by paper chromatography followed by detection with a mercury acetate—diphenylcarba2one spray reagent. A variety of analytical reactions has been developed for 5,5-disubstituted hydantoias, due to their medicinal iaterest. These reactions are best exemplified by reference to the assays used for 5,5-diphenylhydantoiQ (73—78), most of which are based on their cycHc ureide stmcture. Identity tests iaclude the foUowiag (/) the Zwikker reaction, consisting of the formation of a colored complex on treatment with cobalt(II) salts ia the presence of an amine (2) formation of colored copper complexes and (3) precipitation on addition of silver(I) species, due to formation of iasoluble salts at N. ... 

The proposed reaction mechanism involves intermolecular nucleophilic addition of the amido ligand to the olefin to produce a zwitterionic intermediate, followed by proton transfer to form a new copper amido complex. Reaction with additional amine (presnmably via coordination to Cn) yields the hydroamination prodnct and regenerates the original copper catalyst (Scheme 2.15). In addition to the NHC complexes 94 and 95, copper amido complexes with the chelating diphosphine l,2-bis-(di-tert-bntylphosphino)-ethane also catalyse the reaction [81, 82]. 

A bottle of cuprous chloride solution prepared by standing cupric chloride in strong hydrochloric acid over excess copper burst on standing. In the presence of some complexing agents, copper can react with aqueous media to form hydrogen. Slow pressurisation by this means explains the above explosion (Editor s comments). The metal is also known to dissolve in cyanides and some amine solutions. 

Calixarenes, when in their cone-conformation (54), represent versatile host systems for metalated container molecules and many examples have been reported in the literature (55-61). Reinaud and coworkers have carried out extensive work concerned with calix[6]arenes that are functionalized at the small rim by nitrogen arms (62), aiming to reproduce the hydro-phobic binding site of mononuclear zinc and copper metalloen-zymes. A recent example is the calix[6]arene ligand L1 (Fig. 3), in which a tris(2-methylpyridyl)amine unit covalently caps the calixarene small rim (63). The ligand forms copper complexes of... 

Two other refining processes are also frequently employed. One involves hydrometallurgical refining in which sulfide concentrates are leached with ammonia solution to convert the copper, nickel, and cobalt sulfides into their complex amines. Copper is precipitated from this solution upon heating. Under such conditions, the sulfide-amine mixture of nickel and cobalt are oxidized to their sulfates. The sulfates then are reduced to metalhc nickel and cobalt by heating with hydrogen at elevated temperatures under pressure. The metals are obtained in their powder form. 

Stack and co-workers recently reported a related jx-rf / -peroxodi-copper(II) complex 28 with a bulky bidentate amine ligand capable of hydroxylating phenolates at - 80 °C. At - 120 °C, a bis(yu,-oxo)dicopper(III) phenolate complex 29 with a fully cleaved 0-0 bond was spectroscopically detected (Scheme 13) [190]. These observations imply an alternative mechanism for the catalytic hydroxylation of phenols, as carried out by the tyrosinase metalloenzyme, in which 0-0 bond scission precedes C - 0 bond formation. Hence, the hydroxylation of 2,4-di-tert-butylphenolate would proceed via an electrophilic aromatic substitution reaction. 

The whole procedure, including the filtration, is performed under a nitrogen atmosphere. To a solution of 3.26 g (24.0 mmol) of ( + )-(5 )-l-phenyl-2-propanamine (amphetamine) in 20 mL of methanol is added a solution of 807 mg (6.0 mmol) of copper(II) chloride in 10 mL of methanol at 25 "C with stirring. After 30 min, 432 mg (3.0 mmol) of 2-naphthalenol in 10 mL of methanol are added and the total volume brought up to 60 mL with methanol. After 20 h, the brown precipitate (a binaphthalenol-copper(II) amine complex) is destroyed with 40 mL of 4 N hydrochloric acid. After all of the precipitate is dissolved, 100 mL of water are added and the product crystallizes from the solution. It is isolated by filtration, and dried in vacuo yield 421 mg (98%) 96% ee (T-isomer). 

The results show that a number of ruthenium carbonyl complexes are effective for the catalytic carbonylation of secondary cyclic amines at mild conditions. Exclusive formation of N-formylamines occurs, and no isocyanates or coupling products such as ureas or oxamides have been detected. Noncyclic secondary and primary amines and pyridine (a tertiary amine) are not effectively carbonylated. There appears to be a general increase in the reactivity of the amines with increasing basicity (20) pyrrolidine (pKa at 25°C = 11.27 > piperidine (11.12) > hexa-methyleneimine (11.07) > morpholine (8.39). Brackman (13) has stressed the importance of high basicity and the stereochemistry of the amines showing high reactivity in copper-catalyzed systems. The latter factor manifests itself in the reluctance of the amines to occupy more than two coordination sites on the cupric ion. In some of the hydridocar-bonyl systems, low activity must also result in part from the low catalyst solubility (Table I). 

Copper (II) salts have been found to be inactive as catalysts for the reaction with the exception of the copper (II) carboxylates which are considerably less reactive. In addition, the polymerization of 2.6-xylenol in pyridine with copper (II) acetate as catalyst appears to terminate before high molecular weight polymers are formed. However, treatment of an amine complex of a copper (II) salt with an equivalent of a strong gives the active catalyst. Similarly, although copper (II) hydroxide in pyridine is inactive as a catalyst, treatment with an equivalent of hydrogen chloride generates the active catalyst. Hence it can be concluded that the active catalyst is a basic salt (XV). 

The reaction of imidazole-4,5-dicarbaldehyde with 2-aminoethylpyridine in the presence of copper(II) chloride has enabled the preparation of a binuclear complex (equation 2).29 A more common class of binuclear complex is based on template reactions of a phenolic dialdehyde with various amines and includes the copper complexes (14)30 31 and (15).32 Reactions of this type can be extended to the synthesis of macrocyclic binuclear complexes such as (16).33,34... 

---