Diazomethane preparation

Decane-1 10-dicarboxylic acid from sebacic acid. Convert sebacic acid into the acid chloride by treatment with phosphorus penta-chloride (2 mols) and purify by distillation b.p. 146-143°/2 mm. the yield is almost quantitative. Dissolve the resulting sebacoyl chloride in anhydrous ether and add the solution slowly to an ethereal solution of excess of diazomethane (prepared from 50 g. of nitrosomethylurea) allow the mixture to stand overnight. Remove the ether and excess of diazomethane under reduced pressure the residual crystalline 1 8-bis-diazoacetyloctane weighs 19 -3 g. and melts at 91° after crystaUisation from benzene. 

A solution of 5 mmol diazomethane, prepared from N-methyl-N-nitrosourea (0.62 g, 6 mmol), in 5 mL pentane is added to 1728 a (0.5 g, 5 mmol) [4] at 0°C and the reaction mixture warmed to room temperature. After 30 min the yellow color of CH2N2 has disappeared and the reaction mixture is evaporated. The residue is extracted with boiling pentane to give 0.66 g (93%) 3-tert-butyl-lH-l,2,4-di-azaphosphol, m.p. 74°C [30] (Scheme 11.10). 

Prepare sufficient diazomethane to methylate the sampled as required. Add the diazomethane prepared in toluene (3 mL) to the extract. Seal the flask with a stopper and gently swirl the reaction mixture. Leave the reaction mixture at room temperature for... 

To a cooled soln (-20 °C) of Z-(S)-Trp-OH (20 g, 59 mmol) in dry THF (100 mL), NMM (6.5 mL, 59 mmol) and isobutyl chloroformate (8.1 mL, 70 mmol) were added. The mixture was stirred at that temperature for 30 min and then filtered. An Et20 soln of diazomethane, prepared from nitrosomethylurea (7.2 g, 70mmol), was added to the filtrate. The mixture was stirred for 15 min at 0°C and concentrated to a small volume. Then, 2.5 M ethanolic HQ was added at rt until N2 evolution ceased. Solvents were removed and the residue purified by column chromatography (EtOAc/hexane 1 3). The product was recrystallized (EtOAc/hexane) to give 19 (R =3-methylindolyl) yield 12 g (59%) mp 134-136 °C. 

Dialysis tubing, 713-714, 718 Diazomethane, preparation, 413 Diene, conjugated, determination of, 515-517, 523-524... 

The submitters used an undistilled ethereal solution of diazomethane, prepared from nitrosomethylurea (Note l).3 For use in the hydrogen-deuterium exchange reaction described, ethereal diazomethane solutions prepared by any standard preparative procedures (Note I)2-3,5 appear to be equally satisfactory. 

This valuable method for the conversion of an acid to its next higher homolog has been used to prepare aliphatic, aromatic, and heterocyclic acids. Excellent reviews of the reaction have been published. Diazomethane preparations are described elsewhere (method 500). The acyl chloride is added to an excess of diazomethane in ether or benzene solution. Diazoketones are usually not purified. 

Dehydroalanine 116 desmosine 48, 49 diazo compounds 157 aryl diazonium salts, reactive properties 157 synthesis 160 diazoacetates, analysis of products 165 reactive properties 162 synthesis 164 diazoketones, analysis of products 162 conversion to haloketones 139 reactive properties 165 synthesis 140 diazomethane preparation 141 reactive properties 162 diazonium salts 89 diazonium-IH-tetrazole 90, 95 3,4-dihydroxyproline 52, 53 diimidoesters 69 diisopropylfluorophosphate 130 2,3-dimethylmaleic anhydride 83 dinitrophenylation 79 disulfide bond reduction 103... 

To a solution of 3,5-dimethoxybenzoyl chloride 24 (10.0 g, 0.05 mol) in 50 mL of ether, was added a solution of diazomethane, prepared from N-methyl-iV-nitroso-p-toluenesulfonamide (32 g), portion-wise with... 

Methylation of carboxylic and phenolic hydroxyl groups with diazomethane. Preparation of an ethereal solution of diazomethane. Caution Diazomethane is extremely toxic and explosive, and all operations should be conducted in a well-ventilated hood behind a safety screen. 

In another route to cyclopropanes, diiodomethane is treated with zinc powder (usually activated with copper) to generate ICH2ZnI, called the Simmons-Smith reagent This species is an example of a carbenoid, or carbene-like substance, because, like carbenes, it also converts alkenes into cyclopropanes stereospecifically. Use of the Simmons-Smith reagent in cyclopropane synthesis avoids the hazards associated with diazomethane preparation. 

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