Diazomethane-Alumina

Carboethoxypropyl)zinc iodide, 220 Hexamethylphosphoric triamide, 142 a-Methylbenzylamine, 185 Titanium(IV) chloride, 304 Miscellaneous compounds including polycarbonyl compounds Diazomethane-Alumina, 14... 

From carboxylic acids a-Chloroacetamide, 70 Diazomethane-Alumina, 14 Diphenyldiazomethane, 242 Potassium hydroxide, 258 From other starting materials I-Butyl perbenzoate, 58 Dibromomethyllithium, 93 Di-p,-carbonylhexacarbonyldicobalt, 99... 

Diazomethane-Alumina, 14 Ethers (see also Allylic compounds, Enol ethers, Homoallylic ethers)... 

Chromium(III) chloride-Lithium aluminum hydride, 84 Dialkylaluminum amides, 206 Diazomethane-Alumina, 14 Dibromoalane, 237... 

During the reaction the alumina usually attains a pink color which is due to some decomposition of p-tolylsulfonyldiazomethane. However, the colored decomposition products adhere strongly to the alumina and will therefore not contaminate the final product. If the alumina becomes reddish rather than pink, the type of the alumina in use may be too basic, causing more extensive decomposition of the -tolylsulfonyl-diazomethane the reaction time should then be reduced as much as possible to prevent a considerable decrease in yield. 

Originally, p-tolylsulfonyldiazomethane was prepared by passing an ethereal solution of its precursor, ethyl i 7-nitroso-iV -(j3-toly]8ulfonyI-methyl)carbamate, slowly through a column of alumina, This procedure, which results in yields about 10% higher, is convenient only for small-scale preparations, up to a maximum of 5 g. of p-tolylsulfonyl-diazomethane. The present modification is due to Middelbos, ... 

The methyl ester (100, R = CH3), derived from this A-nor acid by treatment with diazomethane, is different from the ester (102) obtained either by Favorskii rearrangement of 2a-bromo-5a-cholestan-3-one (101) or by the action of cyanogen azide on 3-methoxy-5a-cholest-2-ene (103) followed by hydrolysis on alumina. The ketene intermediate involved in photolysis of (99) is expected to be hydrated from the less hindered a-side of the molecule to give the 2j -carboxylic acid. The reactions which afford (102) would be expected to afford the 2a-epimer. These configurational assignments are confirmed by deuteriochloroform-benzene solvent shifts in the NMR spectra of esters (100) and (102). ... 

Other important porphyrins which can be derived from hemin are hematoporphyrin (5) and mesoporphyrin (6). Hematoporphyrin (5) which is commercially available at a relatively low price is sensitive towards acid due to the 1-hydroxyethyl groups, so commercial samples contain only 60 to 70% of hematoporphyrin. Pure hematoporphyrin dimethyl ester which is a racemic and diastereomeric mixture of four stereoisomers can be obtained by esterification with diazomethane and subsequent chromatography on neutral alumina.84 The pure stereoisomers can be prepared by enantioselective reduction of diacetyldeuteroporphyrin dimethyl ester.85a b The... 

The influence of the modification on the surface atomic ratios of Si Al as measured by ESCA is shown in Table 2. The enrichment of alumina was observed for modified HZSH-5. The surface Si Al ratio was decreased to about one half its original value. It seemed impossible for diazomethane modification to remove the framework alumina of the zeolite. Ve assumed that the enrichment was caused by the migration of the amorphous aluminum oxide to the surface of the zeolite. The mechanism should be studied further in detail. 

Monoesterification of dicarboxylic acids. Chemiabsorption of a dicarboxylic acid on alumina or silica can be used to effect selective esterification of one acid group with diazomethane. The method was demonstrated by conversion of terephthalic acid, C6H4-l,4-(COOH)2) into the monomethyl ester in quantitative yield. 

Mono esters of dicarboxylic acids.1 Aliphatic straight-chain dicarboxylic acids when adsorbed on alumina react with diazomethane to form monomethyl esters in quantitative yield. Terephthalic acid, isophthalic acid, and 1,4-cyclohexanedi-carboxylic acid are also converted selectively to the monomethyl esters. However, phthalic acid does not show any enhanced selectivity under these conditions. Evidently selectivity for monoesterification results from adsorption of one of the acid groups on alumina. 

Methyl O-methyl-7-ketopodocarpate (324) was reduced with sodium boro-hydride to the hydroxyester 325. Birch reduction of 325 followed by acidic hydrolysis and esterification with diazomethane afforded the dienone 326. Reduction of 326 with sodium borohydride followed by acetylation and treatment of the epimeric mixture with m-chloroperbenzoic acid afforded 327. The latter was rearranged with BF3 in ether to yield the ketone 328 which on chromatography over alumina gave the dienone 329. Reaction of 329 with maleic anhydride in refluxing toluene followed by esterification... 

Nagata s method. Reduction of the ketone with sodium borohydride stereoselec-tively led to the alcohol, which on repeated chromatography on basic alumina cyclized to the iminoether, 165. Its conversion into 14-oxodendrobine (97) was achieved by tosylation to the tosylamide and subsequent basic hydrolysis. The authors developed an alternative route from cyanoketone 164 to 14-oxodendrobine (97) by hydrolyzing the nitrile under acidic conditions. The acid formed was esterified with diazomethane and the ketone 166 was reduced stereoselectively with sodium borohydride. Subsequent saponification and acidic lactonization led to 14-oxodendrobine (97). Inubushi et al. also used Borch s method to convert 14-oxodendrobine (97) into dendrobine (82) via the lactimether 167 and reduction. 

Methylation of alcohols. Alcohols can be methylated by diazomethane in the presence of silica gel (30-100 wt. equiv.), silicic acid, neutral alumina, or zeolite. The methylation is faster as the polarity of the alcohol increases. The method is useful for sensitive substrates such as prostaglandins and carbohydrates. 

An alternate procedure was used by Shafer et al. (1966) in their synthesis of p-nitrophenyl diazoacetate. The key to this synthesis was the use of a chloroformate intermediate. To a 16-fold excess of diazomethane in ether (10 ml) was added dropwise a solution of 48.4 mg of p-nitrophenyl chloroformate. After the solution stood overnight at 4°C, the excess diazomethane was removed under a stream of N2 and the ether evaporated under reduced pressure. The residual yellow oil was dissolved in 2 ml of benzene and chromatographed on an alumina column using benzene as the eluant. The first fraction contained 48 mg of product which could be recrystallized from chloroform-hexane (m.p. 92-94°C). These authors reported that several other diazoacetates can be prepared by this procedure. 

Esterification Alumina. Boron trifluoride. Diazomethane. Dimethylformamide dimethyl acetal. Dimethylformamide dineopentyl acetal. Dimethyl sulfite. Diphenyidiazomethane. Ethyldicyclohexylamine. Ion-exchange resins. Isobutene. Methanesulfonic anhydride. 3 % Methanolic HCl (see Acetyl chloride). Methyl iodide. l-Methyl-3-p-tolyltriazine. Poly-phosphoric acid. Sulfosalicylic acid. Sulfuryl chloride. p-Toluenesulfonic acid. p-Tpluene-sulfonyl chloride. Triethylamine. Triethylorthoformate. Trifluoroacetic anhydride. Esterification of phosphoric acid Trichloroacetonitrile. 

Addition of diazomethane to ketosteroids. Alumina-catalyzed (Woelm, neutral, activity 1) reaction of diazomethane with 5a-androstane-17/3-ol-3-one (1) gives as the major product the epoxide (2).1 A minor product is probably a ring-enlarged... 

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