Diazomethane reacting with

A regiospecific addition takes place when diazomethane reacts with an acetylenic ester [17] (equation 26)... 

When diazomethane reacts with certain imines of hexafluoroacetone [5, 146,... 

Diazomethane reacts with ketonic compounds according to the reactions to give epoxides and homologated ketones. If the ketone employed is cyclic, only a single... 

The 1,3-dipolar reagent diazomethane reacts with oxepin and substituted derivatives to afford 1 1 or 2 1 adducts 13 or 14 across the C-C double bonds of the isomeric benzene oxides.238 239 In the 1 1 addition product 13, the two heterocycles adopt a cis orientation.238 The nitrogen can be extruded by irradiation of the dihydropyrazole. 

Carrie and co-workers studied the cycloaddition of oxime esters derived from methyl cyanoacetate and malonate esters 82 (Scheme 8.20) with diazomethane and some monosubstituted derivatives. Thermally labile 1,2,3-triazolines 83 were obtained when tosyloxy- and benzoyloxyimines were used (141), while methyl acetoxyimino-cyanoacetate (82, X = CN, Y = C02Me, = Ac) gave products derived from both a 1,2,3- and a 1,2,4-triazoline, depending on the stmcture of the diazo compound (142). Not unexpectedly, diazomethane reacted with the corresponding imino-malononitrile (82, X = Y = CN) system at the nitrile function rather than at the C=N bond (143). 

Diazomethane reacts with 4-nitrobenzenediazonium chloride to give the 1-aryltetrazole 218 (Scheme 8.52) in addition to other products (277). This long-known reaction was revisited when the dipolarophUic character of the arenediazo-nium salt was realized (278). The tetrazole probably arises by a concerted 1,3-dipolar cycloaddition rather than by a two-step process. However, the observed regiochemistry is difficult to reconcile with either mechanism. 

Diazomethane reacts with 3-nitrochromone (419) under mild conditions to give the cyclopropabenzopyran (420 R = H) and a homologous dimethylcyclopropane (420 R = Me) is obtained from 2-diazopropane. These compounds undergo useful reactions with opening of the small ring (80JCS(Pl)2049). 

CARBENE. The name quite generally used for the methylene radical, CH,. It is formed during a number of reactions. Thus the flash photochemical decomposition of ketene (CH2=C=0) has been shown to proceed in two stages. The first yields carbon monoxide and CHj. the latter then reacting with more ketene to form ethylene and carbon monoxide. Carbcne reacts by insertion into a C- H bond to form a C-CH, bond. Thus carbene generated from ketene reacts with propane to form, i-butane and isobutane. Carbene generated by pyrolysis uf diazomethane reacts with diethyl ether to form ethylpropyl ether and ethylisopropyl ether. 

Diazomethane reacts with thiooxindole to give the spirooxadiazole (207).400 The reactivity of thiooxindole toward amines differs markedly from that of thioindoxyl (Section VI, 1,2).539,641 In most... 

Diazomethane reacts with 2,4,6-trinitrobenzenesulfonic acid with ring opening similar to that observed with 1,3,5-trinitrobenzene.6 Hence an excess of the reagent is to be avoided. The yellow color is not due to the presence of diazomethane itself. The reaction time is highly sensitive to the temperature of the xylene solution and to the flow rate of gaseous dimethyl ether. The reaction time is usually 20-40 minutes. 

Lithio TMS-diazomethane reacts with ketenimines to produce 4-TMS-1,2,3-triazoles or 4-amino-3-TMS-pyrazoles87 88, depending on the keteneimine substitution pattern. 

Diazomethane reacts with the salts of enamines to yield aziridinium salts.327 327a ThusiV-cyclohexylidenepyrrolidinium perchlorate yields 2,2 -pentamethylene-1,1 -tetramet hyleneaziridinium perchlorate (101). Hydrogenation over Adams catalyst cleaves the bond between the quaternary nitrogen atom and the methylene group to form A-(l-methylcyclohexyl)pyrrolidinium perchlorate (102). 

Diazomethane is an electron-rich 1,3-dipole, and it therefore engages in Sustmann type I 1,3-dipolar cycloadditions. In other words, diazomethane reacts with acceptor-substituted alkenes or alkynes (e. g., acrylic acid esters and their derivatives) much faster than with ethene or acetylene (Figure 15.36). Diazomethane often reacts with unsymmetrical electron-deficient... 

Acyl and perfluoroalkyl diazomethanes react with nitrogen oxides, and a-diazosulfones with nitrosyl chloride or dinitrogen trioxide, to give furoxans. The process is believed to involve nitrosation, followed by loss of nitrogen to form the nitrile oxide which subsequently dimerizes. Nitrosation of dimethylphenacylsulfonium bromide with nitric acid/sodium nitrite gives dibenzoylfuroxan. 

The methylene generated from diazomethane reacts with alkenes to form cyclopropanes, but diazomethane is very toxic and explosive, and the methylene generated is so reactive that it forms many side products. A safer and more reliable way to make cyclopropanes is with the Simmons-Smith reagent. 

Steroidal 1,4-dien-3-ones react with phosphorus pentasulphide in an inert solvent to give the purple-blue l,4-diene-3-thiones (235) (Amax330 and 565—580nm).204 The thiones are remarkably stable, but can be oxidized to give syn- and anti-S-oxides, which are separable but are interconverted on standing. Diphenyl-diazomethane reacts with the dienethione at room temperature to give the 3-(diphenylmethylene)-1,4-diene (236) directly.204... 

Phosphoryl diazomethanes react with 2,6-di-/erf-butylthiopyrylium ion (26) in the presence of triethylamine to give the corresponding 4-(di-azomethyl)-4//-thiopyrans 349-353. Reaction of compound 349 or 350 with di-/x-chlorobis-(7r-allyl)palladium(Il), instead of the expected thiepine derivative, afforded the anhydrobase 354 or 355, respectively (85T811). 

Diazomethane reacts with 78 (RX = PO(OEt)2) with an opposite regiochemistry forming pyrazoline 155 and its more stable tautomer 156. Pyrazoles 157 are obtained by treating the mixture of 155/156 with a base <2001T5455>. 

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