Ketone aerial oxidation

Spontaneous aerial oxidation of the initially formed alkoxide is reported in the reaction between a 7-lithiotriazolopyridine and pyridine-2-carboxaldehyde, to give ketone 144 (98T15287). 

Qualitative spot tests for aldehydes, in the presence of ketones, are generally only reliable for water-soluble compounds. This problem can be overcome by the use of 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (Purpald , Aldrich Chemical Company) in the presence of Aliquat (Scheme 5.27). Under aerial oxidation, the initially formed colourless cyclic adduct changes colour through red to purple. The colourless cyclic aminal can also be formed by ketones, but only the adducts derived from the aldehydes are oxidized to the purple bicyclic aromatic system [28]. Weakly electrophilic aldehydes, e.g., 4-methoxybenzaldehyde, reacts slowly, but will give the positive coloration upon gentle heating to ca. 70°C for one or two minutes. 

The pyridazine dioxide derivative (108) was made by intramolecular nitroso compound dimerization as shown (Scheme 23). 1,2-Oxathiin 2,2-dioxides are obtained by the addition of sulfuric acid to a,(3-unsaturated ketones, e.g. (109) — (110) (66HC(21-2)774). 1,2-Dithiins are synthesized from conjugated diynes using benzyl thiol reductive debenzylation of intermediate (111) by sodium in liquid ammonia at - 70°C gives, after aerial oxidation, the 1,2-dithiin (112) (67AG(E)698). 

A sample (0.5-1 ml) of the test solution is added to an equal volume of 4,4 -bis(dimethylamino)benzophenone (Michler s ketone) in dry toluene. A few drops of water are added, and the mixture is shaken." A few drops of a 0.2% solution of iodine in glacial acetic acid are added, resulting in the formation of a blue or green colour. A recent variation employs tris(4-dimethylaminophenyl)methane (leuco crystal violet, LCV), followed by aerial oxidation [1]. 

The reaction of esters of methylenedioxyphthalic acid (387) with the imine (388) affords the ester-lactam (389) and hydrolysis of this to the lactam-acid followed by Arndt-Eistert homologation and cyclisation yields the ketone (390, R R =0). Reduction of this to the secondary alcohol (390, R =H, R =0H), followed by dehydration and aerial oxidation affords oxosangui-narine (391), from which sanguinarine can be prepared (Shamma and H. Tomlinson, J.org.Chem., 1978, 2852). A similar... 

The most common reactions with aldehydes and ketones reported have been those of lithio-imidazoles. The products are usually alcohols, but sometimes ketones are formed on aerial oxidation of the primary products. Access to 2-, 4-, and 5-carbinols is now readily available <94H(38)2487>. 

The diosphenol (214) has been prepared from 3a-bisnorcholanic acid (217), itself obtained from ergosterol. The amino-group is introduced with retention of configuration by means of the Curtius reaction and methylated to give 3a-acetoxy-20a-dimethylamino-5/5-pregnane (216). After hydrolysis and oxidation with chromic acid, the ketone (215) is obtained. Aerial oxidation of (215) in the presence of potassium t-butoxide in t-butyl alcohol gives (214). 

Oxidations Metal-catalyzed aerobic oxidation of organic compounds has been reviewed. Aerial oxidation of primary and secondary alcohols is mediated by TEMPO in the presence of HCl and NaN02- Secondary benzylic alcohols undergo aerial oxidation (or with r-BuOOH) based on catalysis by AuCl - neocuproine," but another report describes the oxidation of both primary and secondary alcohols (to acids and ketones, respectively) using nanoclusters of gold that are stabilized by poly(A-vinyl-2-pyrtolidone). ... 

Hydrazinoquinoxalines are readily converted into hydrazones on treatment with aldehydes or ketones. Attempted formation of the ben-zylidene derivative 4 gives the benzoyl compound 3, presumably as a result of the ready aerial oxidation of the benzylidene derivative." ... 

The reaction between cyclic ketone enolates and diethyl phosphorochloridite followed by aerial oxidation of the intermediate P(III) esters, yields mixtures of C - and (7-phosphorylated products. The formation of the (1 -oxoalkyl)phosphonic diesters was optimized using diethyl ether as solvent (although better yields were sometimes obtained for reactions in Et20/THF when hexamethylphosphoric triamide was added) when the... 

The oxidation of hydrazones has provided two new methods for the preparation of substituted diazomethanes. Ketone hydrazones, upon treatment with sodium in ether and subsequent aerial oxidation, gave diazomethanes (52) in excellent yields (Scheme 50). Similarly, hydrazonoethylidene derivatives yield diazoethylidenes (53) upon oxidation with Mn02 (Scheme 51). ... 

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