Alkyl chlorocarbonate

The addition of a benzene solution of an alkyl chlorocarbonate to an aqueous solution of sodium tclluride (prepared from tellurium and Rongalite in an aqueous solution of sodium hydroxide) containing tetrabutylammonium bromide as a phase-transfer agent produced the bis[alkoxycarbonyl] tellurium at 20 . The reactions can also be carried out in dimethylformamide with sodium telluride obtained from sodium hydride and tellurium in dimethylformamide4... 

Imidazoles have been N-acylated by isocyanates (at elevated tempera-tures) " (Scheme 21), acid halides, and alkyl chlorocarbonates, but 2-methylimidazole would not react with formamide and phosphoryl chloride. Trifluoromethylsulfonation forms the imidazolide which is a convenient reagent for the introduction of the triflate group. ° With highly basic I-substituted imidazoles, acetyl halides form the 1-acetyl-... 

Of the numerous methods reported by Bdhme et al. for the synthesis of preformed iminium salts, the most general and convenient involves cleavage of methylenediamines (23) by acyl halides (24) or alkyl chlorocarbonates (25), providing preformed iminium salts (26) in quantitative yield and in near analytical purity (equation 4). The by-product of these reactions, a dialkylamide (27) or a dialkylurethane (28), is easily removed since it remains in solution during precipitation of the iminium salt. The ionic nature of iminium salts produced by this method is well established, although an equilibrium between the... 

The most successful realization of the mixed anhydride concept is, however, the generation of reactive intermediates with the help of alkyl chlorocarbonates (also called alkyl chloroformates) ... 

Mixed anhydrides prepared from carboxylic acids and alkyl chlorocarbonates are of paricular value for the preparation of amides of sensitive acids such as A -acylated amino acids. The reaction of cyclic dianhydrides with amines yields imides. If diamines are used with dianhydrides, polyimide resins are produced. 

Carbene complexes have also been prepared by transmetallation reactions. Lithiated azoles react with gold chloride compounds and after protonation or alkylation the corresponding dihydro-azol-ylidene compounds, e.g., (381) or (382), are obtained.22 9-2264 Silver salts of benz-imidazol have also been used to obtain carbene derivatives.2265 Mononuclear gold(I) carbene complexes also form when trimeric gold(I) imidazolyl reacts with ethyl chlorocarbonate or ethyl idodate.2266,2267 The treatment of gold halide complexes with 2-lithiated pyridine followed by protonation or alkylation also yields carbene complexes such as (383).2268 Some of these carbene complexes show luminescent properties.2269-2271... 

Perchlorofulvalene is a highly reactive chlorocarbon which undergoes a variety of reactions, including dimerization and addition reactions, especially with nucleophiles. It has a unique structure4 which reflects a compromise between steric hindrance and conjugation. The method of preparation exemplifies the use of the mild dehalogenating properties of alkyl phosphites. 

Only a few unsubstituted, non-stabilized alkyl tellurium halides were characterized or isolated. /-Butyl tellurium chloride may have been detected by l2STe-NMR spectroscopy as a minor product of the controlled chlorination of di-/-butyl ditellurium6. 2-Chlorocarbon-ylbenzyl tellurium halides were obtained as rather unstable solids by halogenolysis of tellurophthalide7 (p. 246). Tris[trimethylsilyl methyl tellurium chloride, bromide and iodide were isolated as black-blue crystals that were stable in solution and as solids8. The stability of these compounds is attributable to the steric protection of the Te —X group by the trimethylsilyl substituents. 

The reagents used for the completion of the purine heterocycle are essentially the same as those used for the Traubc synthesis. The purine ring is formed by condensation with derivatives of formic acid or other carboxylic acids. Alternatively, formylation of the amino group is accomplished by a mixture of formic acid and acetic anhydride followed by cyclization. Alkyl esters or trialkyl ortho esters are also versatile synthons for ring closure. Moreover, heating in formamide or cyclization with urea or thiourea provides a satisfactory route. Condensations with isothiocyanates show unusual versatility leading to 2-sulfanylpurin-6-ols. From carbonic acid derivatives, cyclization is reported with chlorocarbonic esters, diethyl carbonate or carbon disulfide. 

With secondary alcohols the reaction proceeds similarly, but with tertiary alcohols a further decomposition of the chlorocarbonic ester formed takes place and carbon dioxide is evolved and the corresponding alkyl chloride is formed ... 

Baran, J.R., Pope, G.A., Wade, W.H. and Weerasooriya, V. (1996) Water/chlorocarbon winsor I III II microemulsion phase behavior with alkyl glucamide surfactants. Environ. Sci. Technol, 30(7), 2143-2147. 

The enhancement of enantioselectivity cannot be an effect of solubility because water-soluble substrates gave enhanced activities but no enantioselectivity increase [54], Acylation of PPM ((2S,4S)-4-diphenylphosphino-2-diphenylphosphinomethyl-pyrrolidine) with the chlorocarbonic ester of alkyl polyoxyethylene ethers (Brij 4)... 

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