Nitrogen zinc adducts

Tin(Il) shows considerable affinity towards nitrogen, therefore is expected to activate the imino group. The diastereoselective addition of tin(II) enolates derived from thioesters 1 to x-imino-esters 2 is reported12. This reaction proceeds smoothly to afford. vi w-/j-amino acid derivatives 3 (d.r. 95 5) in good yields. Lithium, magnesium, and zinc enolates do not react while titanium enolates give the adducts in low yield with preferential formation of the anti-isomer. 

Zinc dithiocarbamates have been used for many years as antioxidants/antiabrasives in motor oils and as vulcanization accelerators in rubber. The crystal structure of bis[A, A-di- -propyldithio-carbamato]zinc shows identical coordination of the two zinc atoms by five sulfur donors in a trigonal-bipyramidal environment with a zinc-zinc distance of 3.786 A.5 5 The electrochemistry of a range of dialkylthiocarbamate zinc complexes was studied at platinum and mercury electrodes. An exchange reaction was observed with mercury of the electrode.556 Different structural types have been identified by variation of the nitrogen donor in the pyridine and N,N,N, N -tetra-methylenediamine adducts of bis[7V,7V-di- .vo-propyldithiocarbamato]zinc. The pyridine shows a 1 1 complex and the TMEDA gives an unusual bridging coordination mode.557 The anionic complexes of zinc tris( V, V-dialkyldithiocarbamates) can be synthesized and have been spectroscopically characterized.558... 

Heterocyclic nitrogen donors and their adducts with zinc chloride have been studied.623,624 A large number of other ligand systems have also been characterized, for example, zinc halide adducts of 2,2-dimethylpropane-1,3-diamine and hexamethylphosphoramide have been studied.625,626 The formation of mixed ligand complexes with chloride and substituted pyridines has been studied.627 The zinc tris(pyridyl) chloride anion has also been structurally characterized.628 Manganese(II) ions have been used to probe the stereochemistry in reactions of zinc halides with pyrazine.629... 

The mechanism of zinc deprivation by 3-nitrosobenzamide was elucidated most recently. When the reconstituted nucleocapsid protein p7 of HIV-1 (15 i-M) was incubated with 3-nitrosobenzamide (300 iM) at pH 7.5, three disulfide bonds per protein molecule were formed while 3-nitrosobenzamide was reduced to the hydroxylamine. Molecular masses of p7 adducts augmented by one or two 3-nitrosobenzamide residues were observed by electrospray ionization MS, consistent with covalent bond formation between cysteine sulfur and the nitroso nitrogen atom127. 

The ethylzinc amide of mesitylamine crystallizes as a dimeric THF adduct (201) (Figure 97). Also, in this compound the amide nitrogen atom is //. -bonded [Zn—N 2.070(5) and 2.076(5) A] between two zinc atoms. The zinc atoms are distorted tetra-hedrally coordinated by additional coordination of a THF molecule [Zn—O 2.240(5) A]. 

In the nitrogen bag, 50.2 mg of [60]fullerene, ethyl bromoacetate (5 equiv.), zinc dust (20 equiv.) and the stainless-steel ball were placed in the capsule. The above mixture was vigorously agitated for 20 min at room temperature, quenched with 0.5 mL of CF3C02H in 20 mL of o-dichlorobenzene, and carefully separated by silica gel chromatography with hexane-toluene as the eluent to give the expected adduct 1 (17.2%) (62.5% based on consumed C60) together with 2 (0.8%), 3 (3.9%), 4 (1.8%) and unreacted C60 (72.5%). 

The complexes with nickel(II), palladium(II), platinum(II), zinc(Il), cad-mium(II), mercury(II), and lead(II) and their adducts with nitrogen heterocycles have been described. The magnetic moment of the iron(III) complex is temperature-dependent owing to a spin-paired spin-free equilibrium. ... 

Many other 1,3-dipolar cycloadditions are known, amongst which is the addition of diazomethane (CH2N2). Expulsion of nitrogen from the adduct leads to the formation of a cyclopropane ring. Another way of achieving the same result involves the addition of a carbene such as the Simmons Smith reagent. This is generated from methylene iodide (CHjIj) and a zinc/copper couple. 

B s(dialkyldithiocarbamato)zinc(ll) Adducts with Nitrogen Bases. 301... 

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