Copper compounds reaction with diazoketones

Rhodium(II) acetate was found to be much more superior to copper catalysts in catalyzing reactions between thiophenes and diazoesters or diazoketones 246 K The outcome of the reaction depends on the particular diazo compound 246> With /-butyl diazoacetate, high-yield cydopropanation takes place, yielding 6-eco-substituted thiabicyclohexene 262. Dimethyl or diethyl diazomalonate, upon Rh2(OAc)4-catalysis at room temperature, furnish stable thiophenium bis(alkoxycarbonyl)methanides 263, but exclusively the corresponding carbene dimer upon heating. In contrast, only 2-thienylmalonate (36 %) and carbene dimer were obtained upon heating the reactants for 8 days in the presence of Cul P(OEt)3. The Rh(II)-promoted ylide formation... 

Copper powder, copper bronze, Cu O, CuO, CuSO, CuCl and CuBr were the first catalysts which were used routinely for cyclopropanation of olefins as well as of aromatic and heteroaromatic compounds with diazoketones and diazoacetates. Competing insertion of a ketocarbene unit into a C—H bond of the substrate or solvent remained an excpetion in contrast to the much more frequent intramolecular C—H insertion reactions of appropriately substituted a-diazoketones or diazoacetates Reviews dealing with the cyclopropanation chemistry of diazo-acetic esters (including consideration of the efficiency of the copper catalysts mentioned above) and diazomalonic esters as well as with intramolecular cyclopropanation reactions of diazoketones have appeared. 

Starting from 6-methoxynaphth-2-oic acid (64), the 1,2,3,4,5,8-hexahydro-derivative (65) was prepared by reduction with excess lithium and t-butyl alcohol in liquid ammonia. Compound (65) was converted into the keto-acid (66) by hydrolysis. Reduction of (66) with lithium tri-t-butoxyaluminium hydride gave the hydroxy-acid (67). The acetate derivative (68) was converted into the acid chloride (69) by reaction with oxalyl chloride in pyridine. Treatment of this compound with diazomethane afforded the diazoketone (70). Decomposition of the latter with copper powder in cyclohexane gave the cyclopropyl ketone (71) in yields of 70—80%. The acetate function was then hydrolysed, and the resulting hydroxy-ketone (72) was oxidized to the cyclopropyl diketone (73) with Jones reagent. Treatment of (73) with a weakly acidic acetone solution or adsorption on to basic alumina produced the enedione (74) via a retrograde... 

Polymer-supported benzenesulfonyl azides have been developed as a safe diazotransfer reagent. ° These compounds, including CH2N2 and other diazoalkanes, react with metals or metal salts (copper, paUadium, and rhodium are most commonly used) to give the carbene complexes that add CRR to double bonds. Diazoketones and diazoesters with alkenes to give the cyclopropane derivative, usually with a transition-metal catalyst, such as a copper complex. The ruthenium catalyst reaction of diazoesters with an alkyne give a cyclopropene. An X-ray structure of an osmium catalyst intermediate has been determined. Electron-rich alkenes react faster than simple alkenes. ... 

Many substituted tricycloalkanones 22 have been made by copper-catalyzed intramolecular cycloaddition of diazoketones to cycloalkenes. Cleavage of these compounds with the lithium/ammonia reagent (Table 13) provides a useful alternative to acid-catalyzed ring-opening reactions (see Section 2.4.1.3.4.) because it often leads to cleavage in a different mode. 

Rhodium(II) acetate was found to be much more superior to copper catalysts in catalyzing reactions between thiophenes and diazoesters or diazoketones The outcome of the reaction depends on the particular diazo compound With f-butyl... 

Intramolecular reactions of carbenes with alkenes have been exploited in synthesis. The sesquiterpene cycloeudesmol was prepared using, as a key step, the intramolecular cyclopropanation of the diazoketone 122 (4.97). The cyclopropana-tion reaction occurs stereoselectively to give the tricyclic product 123, which was subsequently converted into the natural product. A synthesis of sesquicarene was achieved using the copper(I)-catalysed decomposition of the diazo compound 125, itself prepared by oxidation of the hydrazone 124 (4.98). 

The intramolecular Buchner reaction of aryl diazoketones has been carried out using both copper(I) and rhodium(II) catalysts. For example, 1-diazo-4-phenylbutan-2-one 27a cyclizes in bromobenzene with copper(I) chloride catalysis, furnishing 3,4-dihydroazulen-l(2//)-one 30 in 50% yield after purification by chromatography over alumina. Trienone 30 is not the primary cyclization product, and the less conjugated isomeric trienone 29a is first produced, but contact with alumina causes isomerization to 30. The yield of this cyclization is further improved when rhodium(II) acetate is used as the catalyst instead of copper(I) chloride. Thus a catalytic amount of rhodium(II) acetate brings about the nearly quantitative conversion of 27a to 29a within minutes in hot dichloromethane. Compound 29a isomerizes to 30 on treatment with triethylamine, and rearranges to 2-tetralone 31a when exposed to silica gel or acid. 

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