Diazoacetic ester, decomposition

Decomposition of the diazoacetic ester (548) to the keto carbene (549) is promoted by copper(II) trifluoromethanesulfonate. In the presence of nitriles, 1,3-dipolar addition to the nitrile occurred giving the oxazole (550) (75JOM(88)ll5) (see also Section 4.03.8.1). 

In this review an attempt is made to discuss all the important interactions of highly reactive divalent carbon derivatives (carbenes, methylenes) and heterocyclic compounds and the accompanying molecular rearrangements. The most widely studied reactions have been those of dihalocarbenes, particularly dichlorocarbene, and the a-ketocarbenes obtained by photolytic or copper-catalyzed decomposition of diazo compounds such as diazoacetic ester or diazoacetone. The reactions of diazomethane with heterocyclic compounds have already been reviewed in this series. ... 

The copper-catalyzed decomposition of diazoacetic ester in the presence of pyrrole was first described in 1899 and later investigated in more detail by Nenitzescu and Solomonica. Ethyl pyrrole-2-acetate (13), the normal product of electrophilic substitution, was obtained in 50% yield and was degraded to 2-methylpyrrole. Similarly iV -methylpyrrole with two moles of diazoacetic ester gave, after hydrolysis, the 2,5-diacetic acid (14) while 2,3,5-trimethylpyrrole gave, after degradation, 2,3,4,5-tetramethylpyrrole by substitution of ethoxycarbonylcarbene at the less favored )3-position. Nenitzescu and Solomonica also successfully treated pyrroles with phenyl-... 

Jackson and Manske described the decomposition of diazoacetic ester with indoles to give, after hydrolysis, the 3-acetic acid and some 1,3-diacetic acid no product of 2-substitution was found (see also ref. 49). Diazoacetone and diazopyruvic ester similarly gave the 3-sub-stituted indoles.Badger et al. have also examined the reaction of iV -methylindole, as well as of indole, with diazoacetic ester. Again only the 3-substituted product resulted and no evidence was obtained for addition. 

Although the hazardous properties of di-tert-butyl diazomalo-nate are not known with certainty, it is reasonable to assume that they are similar to those of diazoacetic esters, which are considered to be moderate explosion hazards when heated. Contact with rough or metallic surfaces should be avoided. The submitter has routinely distilled 10-g. quantities of di-ferf-butyl diazomalonate under argon with no sign of decomposition. 

Vinyloxysilyl)diazoacetic esters 3 give rise to oxasilacyclopentenes 4 or 5, depending on the mode of decomposition. Heterocycle 4 cannot be converged to 5 under the photochemical or thermal conditions applied for the synthesis of 5. 

Ethyl 2-fluoroethoxyacetate, F [CH2]2 0 CH2 C02Et, could not be prepared by the action of ethyl diazoacetate on pure redistilled 2-fluoroethyl alcohol, and the addition of a small quantity of concentrated hydrochloric acid had no effect, which is rather surprising in view of the known catalytic action of acids on the decomposition of the diazoacetic ester. However, fluoroethyl alcohol which had not been specially dried reacted immediately with ethyl diazoacetate with a vigorous evolution of nitrogen and the simultaneous disappearance of the yellow colour of the diazo ester. 

Georg Bredig (1868-1944)137 138 was essentially a physical chemist, who worked in catalysis, reaction kinetics, and electrochemistry. For physical organic chemistry his studies of the catalysed decomposition of diazoacetic ester, of reactions in concentrated sulphuric acid, and of the catalysis of the benzoin condensation by cyanide ion are of interest. The last-mentioned work was done in 1904, when Bredig confirmed,... 

Aliphatic diazocarbonyl and related diazo compounds can be decomposed by either photolysis or pyrolysis (or thermal decomposition), or by transition-metal-catalyzed decomposition generates (Scheme 2.51). For example, pyrolysis of diazoacetic ester at 425°C gives the carbethoxy carbene. 

Under the conditions of homogeneous catalysis, decomposition temperatures are normally significantly lower than with the heterogeneous catalysts mentioned above, and cyclopropane yields in general are higher. However, catalysts of type 2 must first be converted into the active form [presumably a copper(I) monochelate] by brief heating or by in situ reduction (see Table 10). Another soluble catalyst, copper(I) triflate, even decomposes diazoacetic esters and diazomalonic esters at temperatures below 0 °C and sterically more encumbered diazocarbonyl compounds (e.g. a-diazo-a-trialkylsilyl acetic esters " ) still at room temperature, and has shown its effectiveness in a number of cyclopropanation reactions. Since copper(I) triflate is... 

Decarbonylation of cyclopropene acids. In a study of the synthesis of methyl sterculate (6) from methyl stearolate (1), Gensler et al.1 were unable to repeat the apparently straightforward synthesis based on addition of the Simmons-Smith reagent described in 1, 1021-1022. They were also unable to eifect addition of methylene generated by cuprous bromide decomposition of diazomethane. However, the reaction of (1) with diazoacetic ester in the presence of copper bronze, followed by hydrolysis, gives the cyclopropene diacid (2) in 70-90% yield. 

In a similar fashion, the thermal decomposition of diazoacetic ester in benzonitrile at 145° gave 2-phenyl-5-ethoxyoxazole (42%).1M... 

Carbenoid and nitrenoid reactions. Decomposition of diazoacetic esters by the novel Cu complex (1) in the presence of alkenes and alkynes gives cyclopropanes and cyclopropenes, respectively. Similarly, a nitrenoid is generated from TsN=IPh, forming aziridines in similar reactions. 

Bronsted and Volqvartz (Z. physikal. Chem. 1928, 134, 97) had earlier used the specifically hydrogen-ion catalysed decomposition pf diazoacetic ester to determine the acidity constants of some aquo-cations, in particular Fe(H20)J+, Cr(H20)J, and several aquocobalt-ammine cations. 

Ylide Reaction. Yllde formation in catalytic carbene transfer reactions has attracted considerable attention in the past decade. The ylide can be easily generated from a metal carbene and a Lewis base, such as carbonyl compound or sulfide. The highly reactive ylide then proceeds to undergo further reactions. For example, diazoacetic ester (10) is prepared from -phenylthio-2,3-O-isopropylidene D ribofuranose and compound (1). Decomposition of (10) in refluxing benzene containing rhodium(II) acetate results in lactone (11) via an eight-membered cyclic sulfoniumyUde intermediate (eq 9). ... 

The interaction of the capsnle with the diazoacetate esters did not lead to their decomposition. In fact, aU snbstrates remained nnaltered both in the presence and in the absence of the capsnle, even at 50°C for 20 h in water saturated chloroform-d. More interestingly, since this class of molecules are good partners for the 1,3-dipolar cycloaddition reactions with a large series of dipolarophiles [60], their interaction with electron-poor alkenes was investigated in the presence and in the absence of the capsule in order to ascertain its snpramolecular catalytic effects. 

The decomposition, catalysed by copper at elevated temperatures, can be improved by palladium acetate [10] or rhodium acetate at room temperature [11]. Sterically hindered diazoacetic esters give a higher content of trans-isomer in the reaction product [12], as does the employment of diazoacetonitrile [13]. Intramolecular decomposition leads to precursors of cis-chrysanthemic acid [14]. Substituted furfu-ryldiazoacetats yield the final insecticides directly [15]. 

Particularly the diazoacetic method has a certain appeal for this problem. The decomposition of the sterically hindered diazoacetic ester 74 is effective in the presence of 2,4-dimethyl-hexadien-2,5 75 involving transient unsymmetrical carbon-complexes with chiral copper complexes 76 of highly substituted schiff bases of saUcyhc aldehyde [116] affording the 1-R-trans ester 77 in high optical and chemical yield (Reaction scheme 45) [114]. 

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