Cupric acetate, preparation

Cyclodecanedione has also been prepared by oxidation of sebacoin with chromium trioxide in acetic acid, - Cupric acetate in acetic acid has been used for oxidation of an a-hydroxyketone by Ruggli and Zeller. ... 

A solution of bismuth trioxide in hot glacial acetic acid provides a specific method for the oxidation of acyloins. " The reaction rate is dependent on the steric accessibility of the ketol system. A 2,3-ketol requires less than one hour for completion but an 11,12-ketol is not yet fully oxidized in thirty hours." The reaction is highly selective as a-keto acids, hydrazines and phenols are not oxidized. In a direct comparison with cupric acetate, this procedure is somewhat superior for the preparation of a 2,3-diketone from a 2-keto-3-hydroxy steroid. ... 

Recently, the required heteroaromatic organozinc halides for the Negishi reaction have also been prepared using microwave irradiation [23]. Suna reported that a Zn - Cu couple (activated Zn), prepared using a slightly modified LeGoff procedure from Zn dust and cupric acetate monohydrate, allowed the smooth preparation of (3-pyridinyl)zinc iodide and (2-thienyl)zinc iodide... 

In the preparation of D-glucosone by the direct oxidation of D-glucose, D-fructose, or D-mannose by such reagents as that of Fenton,37 cupric acetate,16- 46- 46 selenious acid,16-61 etc., the degree of oxidation must be carefully controlled if the osone, which is the first product, is to be the main product of the reaction. The nature and mechanism of formation of the products of further oxidation of D-glucosone are discussed on p. 68. 

B. Phenylglyoxal. The phenylglyoxal hemimercaptal prepared as described in procedure A (69-74 g.) is dissolved in 400 ml. of warm chloroform, and 60 g. (0.30 mole) of powdered cupric acetate monohydrate is added in one portion to the well-stirred solution. The mixture is stirred at room temperature for 1 hour the solids are removed by suction filtration and washed with two 75-ml. portions of chloroform. The combined chloroform filtrate and washings are shaken in a separatory funnel with 75 ml. of water 20 g. of powdered sodium carbonate is added in small portions to the funnel, and the chloroform solution is shaken with the neutralized aqueous solution. (Cautionl Carbon dioxide is evolved.) The aqueous layer is separated and extracted with four 30-ml. portions of chloroform. The chloroform solutions are combined and dried with anhydrous magnesium sulfate, and the chloroform is removed under reduced pressure. The residue is fractionally distilled under reduced pressure to yield 43-49 g. (64-73%, based on ethyl benzoate) of anhydrous phenylglyoxal as a yellow liquid, b.p. 63-65° (0.5 mm.). 

Attempted Preparation of Bis-(4-methyliminopentane-2-ono)copper(II). A solution of the ligand (2.3 grams, 0.01 mole) in 15 ml. of 95% ethanol was added to an ammoniacal cupric acetate solution, which was prepared as in the preceding synthesis. The mixture was heated on a steam bath for about 15 minutes and a gray precipitate formed. The solid was filtered off, washed with water, and dried (yield 1.6 grams), m.p. 185-87° (dec.). Anal. Calcd. for Ci0Hi6N2O2Cu (imino derivative), C, 46.22 H, 6.21. Found C, 46.27 H, 610. 

Stone78 subsequently reported an improved method for preparing aldos-2-uloses from aldoses. D-Xylose was directly oxidized to D-threo-pentos-2-ulose-(in 34% yield) by cupric acetate in the presence... 

By adding l4C-labelled sodium cyanide to L-threo-pentos-2-ulose (9), L-[l-14C]ascorbic acid was prepared (see Scheme 2) having an activity592-596 of 2.1 x 108 counts, min-1, mg-1. L-Xylose was prepared by the sequence shown in Scheme 21. The resulting L-xylose was oxidized with cupric acetate to 9 in 40-50% yield. In the second procedure, [1-14C]1 (specific activity 0.1 /iCi. mg-1) was purified by way of 5,6-O-cyclohexylidene-L-ascorbic acid.596... 

A more-direct method of preparation is oxidation of aldoses, and optimal yields are afforded by the action of cupric acetate in methanol or ethanol.417 This method is suitable for large-scale preparation of intermediates however, a pure product is obtained only by chromatographic separation from the unreacted sugar byproducts. The synthesis of D-eryt/wo-pentos-2-ulose and its D-threo isomer by oxidation of D-arabinose and D-xylose, respectively, with cupric acetate followed by anion-exchange chromatography has been reported.418 The only product obtained by oxidation of D-glucose with sodium 2-anthraquinonesulfonate in alkaline... 

The copper phthalate eluant was prepared by mixing a solution of cupric acetate with an excess of potassium hydroxide and filtering the resulting cupric hydroxide precipitate. The cupric hydroxide precipitate was then mixed with an equimolar amount of phthalic acid and heated gently overnight to produce copper phthalate. 

A solution or suspension of the acid (1 mmol) in carbon tetrachloride (75 ml) containing DIB (0.55 mmol) and iodine (0.5 mmol) was irradiated with two 100 W tungsten-filament lamps for 45 min at reflux temperature. Another portion of DIB (0.55 mmol) was then added and irradiation was continued for 45 min at reflux. The reaction mixture was washed with dilute sodium thiosulphate and water, concentrated and chromatographed (silica gel column, 9 1 hexanes-ethyl acetate) to afford the alkyl iodide. Several steroidal acids with the carboxyl group attached at a 1° or 2° carbon atom gave the corresponding iodides in good yields. Acids with a 3° a-C instead of the iodide afforded alkenes similarly, alkenes were formed with a fivefold excess of DIB in the presence of cupric acetate. Aromatic acids also underwent iododecarboxylation, in moderate yields very effective was the otherwise difficult transformation of 1,8-naphthalenedicarboxylic acid to 1,8-diiodonaphthalene (80%) [68]. Cubyl and homocubyl iodides were also prepared in excellent yield [69]. 

In the oxidative coupling of primary aromatic diamines to azopolymers cupric ion/nitrogen base complexes serve as homogeneous catalysts. Such complexes are best prepared in situ by oxygenating a cuprous species, preferably CuCl or Cu O/HCl, in the presence of the nitrogen base. Cupric salts investigated except for cupric acetate yielded inactive species. 

The catalyst system for the coupling reaction was a Pd(II)-tri-phenylphosphine complex, usually prepared in situ, with excess triphenyl-phospUne and either cuprous iodide or cupric acetate as a co-catalyst. Alternatively, a preformed catalyst mixture prepared from these reagents may be utilized (see Experimental Section). When 2-methyl-3-butyn-2-ol was used as the protected acetylene, the intermediates 5a-d were converted to the corresponding aryl acetylenes 6a-d by a retro-Favorskii-Babayan (8) reaction utilizing potassium r-butoxide in toluene under conditions of slow distillation. In the case of p-iododimethylaniline (3e), trimethylsilylacetylene was used as the ethynyl source. The intermediate (5e) was treated with hydroxide to generate the free aryl acetylene 6e. The syntheses of 6d and 6e are described in the Experimental section below. 

The plant bufadienolide scillarenin (500) has been synthesized. The starting material was 15a-hydroxycortexone (501), which was converted into the diketone ketal (502) by cupric acetate oxidation at C(21), followed by selective ketalization and tosylate elimination. Protection at C(3) as the dienol ether, oxiran formation at C(20) with dimethylsulphonium methylide, and regeneration of the C(3)- and C(21)-oxo-groups by acid hydrolysis then provided (503). Selective reaction at C(21) with the sodium salt of diethyl methoxycarbonyl-methylphosphonate, and boron trifluoride rearrangement of the epoxide ring to the aldehydo-unsaturated ester (504), was followed by enol lactonization to the bufadienolide (505). This was converted, in turn, to scillarenin (500) via the 14,15-bromohydrin, by standard reactions. Unsubstituted bufadienolides have also been prepared by the same method. 

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