Diethyl diazomalonate

Geminal difluorination ot diethyl diazomalonate can be effected with molecu lar fluorine (10% in nitrogen) to give diethyl difluoromalonate m 70% yield [90] (equation 27)... 

Copper-catalyzed reactions are particularly effective with a-diazo-P-dicarbonyl compounds such as diethyl diazomalonate. 

The question as to whether enol ether 72, the insertion product derived from diethyl diazomalonate and 1-methoxycyclohexene, has a similar origin or arises from a dipolar intermediate of type 102, has already been discussed (Sect. 2.3.1). Interestingly enough, only one formal C/H insertion product was reported in that case, rather than three as in the reaction with 1-methylcyclohexene. 

In contrast to ethyl diazoacetate, diethyl diazomalonate reacts with allyl bromide in the presence of Rh2(OAc)4 to give the ylide-derived diester favored by far over the cyclopropane (at 60 °C 93 7 ratio). This finding bespeaks the greater electrophilic selectivity of the carbenoid derived from ethyl diazomalonate. For reasons unknown, this property is not expressed, however, in the reaction with allyl chloride, as the carbenoids from both ethyl diazoacetate and diethyl diazomalonate exhibit a similarly high preference for cyclopropanation. 

Exclusive O/H insertion takes place in the Rh2(OAc)4-catalyzed reaction of diethyl diazomalonate with a,(J-unsaturated y-hydroxyesters 167 a-c163). This is not surprising in view of the reluctance of electrophilic metal carbenes to add to electron-poor double bonds (see Sect. 2.3.2). However, the more electron-rich double bond of p-methoxybenzyl clavulanate 168 also cannot compete with the O—H function for the same carbenoid 164). The steric situation at the trisubstituted double bonds of 167 and 168 may be reason enough to render an attack there highly unfavorable as compared to the easily accessible O—H function, no matter how nucleophilic the double bond is. 

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... 

Diazo-l,2,3-triazole, 0678 3-Diazo-3//-l,2,4-triazole, 0677 Di-/er/-butyl diazomalonate, 3411 Dicyclopropyldiazomethane, 2824 Dideuterodiazomethane, 0336 Diethyl diazomalonate, 2828 Dinitrodiazomethane, 0545... 

There is just one example of the reaction of thianthrene with a carbene, generated either by decomposition of diethyl diazomalonate at 140°C in the presence of CUSO4 (82JHC833) or using PhI" -C (CN)2 as a precursor [87JCR(S)374] and producing 50. 

In 1984, a facile synthesis of pyrrolo[3,4-/7]indole (5) as a stable indole-2,3-quinodimethane analogue using an intramolecular azide-alkene cycloaddition-cycloreversion strategy was reported (Scheme 9.2) (3). Treatment of bromo compound 3 with NaNs in aqueous tetrahydrofuran (THF) produced the triazoline 4 via an intramolecular 1,3-dipolar cycloaddition of an intermediate azide. Treatment of the triazoline 4 with p-toluenesulfonic acid (p-TSA) effected 1,3-dipolar cycloreversion of 4 to give pyrroloindole 5 in 82% yield along with diethyl diazomalonate. 

The manner in which a carbene was generated was found to be critical to the product distribution in a synthesis of 4(5//)-thiooxazolones (Scheme 6.9). Treatment of diethyl bromomalonate with excess triethylamine in the presence of benzoyl isothiocyanate afforded a mixture of the 4(5//)-thiooxazolone 25 (44%) and the 1,3-oxathiole 26 (minor). However, if the carbene was generated via copper-catalyzed decomposition of diethyl diazomalonate, then 26 was isolated as the major product, albeit in low yield (22%). 

A rare example of this type of reaction is the formation of (189) in the rhodium catalyzed reaction of di-f-butylthioketene with diethyl diazomalonate. This involves the oxathiole (188) as an intermediate, which undergoes electrophilic attack by the carbenoid to give (189). An X-ray structure was determined (89TL1249). 

This method was extended to different diazonium salts and several arsonium ylides (14) were prepared (23, 32). The reaction is greatly facilitated by the presence of copper, copper-bronze, or copper salts. For example, attempts to prepare the bis(carbethoxy)methylene ylide by thermolysis of diethyl diazomalonate in the presence of triphenylarsine without the presence of a catalyst proved abortive, whereas this ylide was obtained in 61% yield if the reactants were heated at 150°C with copper-bronze (32). 

The diazo compound (181a), prepared from the nitrosamine, cyclized to a pyrrolopyrazoline in 80% yield.98 The diazo compound (181b), prepared from diethyl diazomalonate and allylamine, cyclized similarly but at a much more rapid rate. This is consistent with the lowered LUMO of the dipole of (181b), substituted with an ester group here the dipole LUMO-dipolarophile HOMO is the likely dominant interaction. The N—N double bond of the pyrrolopyrazoline products was readily isomerized to afford A2-isomers. 

The bromomethylindole (200a) cyclized on treatment with sodium azide to give a tetracyclic triazoline.111 Treatment with a catalytic amount of p-toluenesulfonic acid afforded 2,4-dihydropyrrolo[3,4-bjindole (201), presumably via loss of diethyl diazomalonate by cycloreversion and subsequent tautomerization. 

The production of buta-1,3-dienes (37) by reaction of 1,2-diarylcyclopropenes with dihalocarbenes is thought to involve electrophilic attack of the carbene to give a dipolar intermediate (38).51 The addition of carbene to CO and H2C=0 has been studied by MNDO calculations.52 Photolysis of diethyl diazomalonate in a CO matrix at low temperature gave rise to ketenes by immediate trapping of the postulated carbene (39).53 The major products of reaction between dichlorocarbene and cyclone were CO and the gem-dichloro species (40).54 The predominance of this pathway over formation of the dichlorooxirane or the cyclopropane is attributed to the aromatic nature of the carbonyl ylide and its twist geometry. 

Diethyl chlorophosphate, see Diethyl phosphorochloridate, 1675 Diethyl diazomalonate, 2824 Diethyl-3-diethylaminopropylaluminium, 3408 Diethyl l,4-dihydro-2,6-dimethylpyridine-3,5-dicarboxylate, 3609 3,6-Diethyl-3,6-dimethyl-1,2,4,5-tetraoxane, 3047... 

Diazoindene, 3110 Diazomalonic acid, 1078 Diazomalononitrile, 1340 Diazomethane, 0405 5-(Diazomethylazo)tetrazole, 0715 Diazomethyldimethylarsine, 1236 3-Diazopropene, 1132 a-Diazo-y-thiobutyrolactone, 1430 Di-terf-butyl diazomalonate, 3405 Dicyclopropyldiazomethane, 2820 Dideuterodiazomethane, 0335 Diethyl diazomalonate, 2824 Dinitrodiazomethane, 0542... 

Diethylaminoethyl chloride hydrochloride Diethyl diazomalonate DiethyUndoloindole DiethyUsopropylsilyl... 

Diethyl diazomalonate (142) reacts with allyl bromide in the presence of a Rh catalyst to produce only minor amounts of the cyclopropane 174 together with the ylide derived malonate ester (173) . With allyl chloride the electrophilic cyclopropane derivative 174 is produced predominantly (equation 41). 

Examples of the oxidation of aliphatic hydrazones are the conversion of acetone hydrazone into 2-diazopropane [386, 392], of hexafluoroacetone hydrazone into 2-diazohexafluoropropane [445], of 4-octanone hydrazone into 4-diazooctane [386], and of the hydrazone of diethyl mesoxalate into diethyl diazomalonate [935] (equations 457 and 458). 

The diazocompounds, such as azibenzil [107], 2,3,4,5-tetraphenyldiazocyclopenta-diene [108], diazodimedone [109], and diethyl diazomalonate [106], whose anion radicals decompose to relatively stable carbene anion radicals, are all derived from compounds with relatively low pKa values (from 13 to 18 in DMSO). It thus seem essential for the lifetime of the carbene radical anion that the negative charge can be accommodated in the structure [110]. 

Exclusive O/H insertion takes place in the Rh2(OAc)4-catalyzed reaction of diethyl diazomalonate with a,P-unsaturated y-hydroxyesters 167 a-c This is not... 

Diethyl diazomalonate is conveniently prepared from diethyl mesoxalate (1, commercially available) in 67% overall yield by condensation with hydrazine and oxidation of the hydrazone with silver oxide in THF.12a... 

As part of a project to synthesize stable analogs of the indole-2,3-quinodimethane system, the 2,4-di-hydropyrrolo[3,4]indole (251) has been prepared from formylindole (249). Knoevenagel condensation with ethyl malonate followed by bromination and nucleophilic substitution of the bromide with azide yields (250), which immediately undergoes intramolecular 1,3-dipolar cycloaddition to give the triazoline (252). Treatment of (252) with toluene-p-sulfonic acid affords diethyl diazomalonate and (251 ... 

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