Diazomethane Compound

With diazomethane, compound 109, 110 gave a mixture of O-methyl and V-methyl derivatives60 lEq. (74). but other methylating agents gave... 

Note that 2-dimethoxyphosphoryl-l,l-dimethylcyclopropane (3) can also be obtained by intramolecular C-H bond insertion of the carbene resulting from (/ert-butyl)(dimethoxyphos-phoryl)diazomethane. Compound 3 was obtained in 9% yield by the copper-catalyzed decomposition method, and in 21% using photolysis, while by [2-fl] cycloaddition, the yield was only 14%. - ... 

Szilagyi et al. (83H765) (Scheme 27) compared the methylation of pyrazol-3-one 86 both on N1 and the carbonyl oxygen of the ring using methyl iodide, dimethyl sulfate, or diazomethane. Thus with methyl iodide or dimethyl sulfate the results were similar, l-methylpyrazol-3-one 87 and methyl 5-methoxypyrazole-3-carbox-ylate 88 were obtained in a ratio of about 1 5, whereas with diazomethane, compounds 87 and 88 were obtained in a ratio of 5 1. 

In connection with the biogenetic path of manzamenones and related Plakortis metabolites, we isolated 3-carboxy-5-(carboxymethyl)-4-tetradecyl-l-oxacyclopent-3-en-2-one (73) [38] from the same Plakortis sponge collected off Manzamo. The structure of compound 73 was defined by extensive spectroscopic analyses. On treatment with diazomethane compound 73 was converted into a dimethyl ester (74), indicating the presence of two carboxylic acids. From the 2D NMR studies, compound 73 was suggested to have a y-butenolide structure with... 

Phenolic alkaloids are present in both S. strictum and S. namaquense. Three of these bases have been shown to belong to the mesembrine subgroup and have been characterized as 4 -0-demethylmesembranol (24) (25), 4 0-demethylmesembrenol (25) (25), and 4 -0 demethylmesembrenone (2Q (27). The essential features of the structures of each of these phenolic alkaloids were apparent by their conversion to known bases by methylation with diazomethane. Compound 25 was converted to 24 by catalytic hydrogenation, indicating that the phenolic hydroxyl occupied the same site in both compounds. 

CHR) , formed, e g. from the reaction of diazomethane and alcohols or hydroxylamine derivatives in the presence of boron compounds or with metal compounds. Poly-methylene is formally the same as polyethene and the properties of the various polymers depend upon the degree of polymerization and the stereochemistry. 

Diasomethane Method. Diazomethane readily methylates phenolic hydroxy-compounds, primary and secondary amines, and carboxylic acids,... 

The cj/cioheptan9ne is readily separated by taking advantage of the experimental fact that it alone forms a soUd bisulphite compound. Diazomethane is conveniently generated in situ from p-tolyl.sulphonylmethylnltrosamlde (Section VII,20). 

Liquid diazomethane CHjjNj, b.p. —24°, is an explosive compound and explosions may also occur in the gaseous state if the substance is dry and undiluted. The gas may be handled with safety by diluting it with nitrogen. For synthetical work, a dry ethereal solution of the gas is employed and this can be handled with safety due regard must, however, be paid to the poisonous... 

Methylation with diazomethane may be carried out as follows (FUME CUPBOARD )-. Dissolve 2-3 g. of the compound (say, a phenol or a carboxylic acid) in a little anhydrous ether or absolute methanol, cool in ice, and add the ethereal solution of diazomethane in small portions until gas evolution ceases and the solution acquires a pale yellow colour. Test the coloured solution for the presence of excess of diazomethane by removing a few drops into a test-tube and introducing a glass rod moistened with glacial acetic acid immediate evolution of gas should... 

Diazomethane alkylation of A-4-thiazoline-2-ones (36, 214) or the Williamson reaction of 2-halogenothiazoles (6. 287-300) provide good yields of 2-alkoxythiazole otherwise obtained by reaction between O-esters of monothiocarbamic acid with a-halocarbonyl compounds (see Chapter II). 

Ecample Suzuki et. al. used a reaction strategy to expand the Cgo molecule, buckminsterfullerene, by adding divalent carbon equivalents. Adding phenyl diazomethane to Cgo. (I)> followed by the loss of molecular nitrogen, results in a Cgi compound. 

Carbon—nitrogen double bonds in imines, hydrazones, oximes, nitrones, azines, and substituted diazomethanes can be cleaved, yielding mainly ketones, aldehydes and/or carboxyHc acids. Ozonation of acetylene gives primarily glyoxal. With substituted compounds, carboxyHc acids and dicarbonyl compounds are obtained for instance, stearoHc acid yields mainly azelaic acid, and a smaH amount of 9,10-diketostearic acid. 

Cinnolin-3(2//)-one (7) is methylated with diazomethane or methyl sulfate to give 2-methylcinnolin-3(2H)-one. In a similar manner, benzylation with benzyl chloride, cyanoethylation with acrylonitrile in the presence of benzyltrimethylammonium hydroxide and glucosidation with tetra-O-acetyl-a-o-glucopyranosyl bromide in the presence of a base affords the corresponding 2-substituted cinnolin-3(2//)-ones. However, glucosidation of the silver salt of cinnolin-3(2//)-one produces the corresponding O-substituted compound. 

Sometimes compounds which exist predominantly in the hydroxyl form give products of N-methylation with diazomethane, for example 3-hydroxy-5-phenylisothiazole (63AHCi2)245) of course, the ambident anion (493) is an intermediate. 3-Hydroxypyrazoles, under rather severe conditions, can be converted into 3-chloropyrazoles with POCI3 <66AHQ6)347). 

These compounds generally exist in carbonyl forms. The oxygen function can be converted into halogen by phosphorus halides. Reactions with electrophiles are quite complex. Thus urazole (511) reacts with diazomethane quickly to yield (512), which is more slowly converted into (513). 1-Phenylurazole gives (514) however, 4-phenylurazole yields (515). Oxadiazolinones of type (516) can be alkylated at both O- and N-atoms. 

Pyrazoles are formed when the diazo compounds react with alkynes or with functionalized alkenes, viz. the enols of /3-diketones. Pyrazolenines (353 Section 4.04.2.2.1) are isolated from disubstituted diazomethanes. Many pyrazoles, difficult to obtain by other methods, have been prepared by this procedure, for example 3-cyanopyrazole (616) is obtained from cyanoacetylene and diazomethane (7iJCS(C)2i47), 3,4,5-tris(trifiuoromethyl)pyrazole (617) from trifluorodiazoethane and hexafluoro-2-butyne (8lAHC(28)l), and 4-phenyl-3-triflylpyrazole (618 R =H) from phenyltriflylacetylene and diazomethane (82MI40402). An excess of diazomethane causes iV-methylation of the pyrazole (618 R = H) and the two isomers (618 R = Me) and (619) are formed in a ratio of 1 1. 

Even more recent calculations using STO-3G and 6-31G basis sets could not safely predict diazomethane as the more stable compound in comparison with diazirine, although there is an experimental energy difference of 125 kJ moP 79JST(52)275). 

The energy difference between diazirine and diazomethane, interesting from the point of view of their isomerism, came from MS measurements (63JCP(39)3534). The appearance potentials of the CH2 ion, common to both compounds, yielded a difference in heats of formation of 125kJmor A strong peak in the mass spectrum of 3-chloro-3-methyl-diazirine (50) with relative mass 55 was ascribed to the methyldiazirinium ion (51). 

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