Ethyl diazo acetate

In 1978, Nakamura and coworkers studied the decomposition of the carbe-noid prepared from ethyl diazoacetate and various palladium complexes [53]. They have found that the use of several chiral hgands did not induce any appreciable enantioselectivity when the cyclopropanation was carried out with ethyl diazo acetate and styrene. From these observations, it was postulated that the chiral ligand did not seem to be tightly bound to the active catalytic species. 

A new pathway for catalytic aziridination was uncovered recently by Brookhart and Templeton [30]. Standard Lewis acids such as BF3, AICI3, and TiCl4 were found to promote the reaction of ethyl diazo acetate with imines to generate the corresponding aziridines in good yield. A simple mechanism involving imine activation and alkylation by the diazo compound was advanced to account for this result (Fig. 6). 

Cyclopropanation reactions with these catalysts are typically carried out with 0.5-2 mol% (with respect to the diazo compound) of catalyst and a five- to tenfold excess of alkene. Under these conditions, the formation of formal carbene dimers [e.g. diethyl ( )-but-2-enedioate and (Z)-but-2-enedioate from ethyl diazo acetate], arising from the competition between alkene and the metal-carbene intermediate for the diazo compound, can be largely suppressed. It has been shown, however, that the control of the addition rate of the diazoacetic ester has no effect on the cyclopropane yield with (dibenzonitrile)palladium(II) chloride as catalyst, in contrast to tetraacetatodirhodium, Rh6(CO)16, and CuCl P(OR)3.152... 

Aldol type addition of the ethyl diazo acetate 170 to indan-l,2-dione is particularly facile and catalyzed by the base.79... 

The ruthenium porphyrins, (TPP)RuCO and (TMP)RuCO catalyze carbene insertion into S - H bonds, leading to dialkyl and alkyl aryl sulfides using ethyl diazo acetate under mild conditions. The insertion process is regiospe-cific since dithiothreitol reacts to give the S - H insertion product without any trace of the ether compound (Scheme 18) [172]. With a homochiral porphyrin ruthenium complex, asymmetric insertions were obtained but with low enantioselectivities [191]. 

The catalytic effectiveness of ruthenium porphyrins for ylide generation in reactions of ethyl diazo acetate and diisopropyl diazomethylphosphonate with some allylic substrates was described for the first time by Simoimeaux and coworkers (Scheme 20) [194]. These reactions result in products of the [2,3]-sigmatropic rearrangement of intermediate allylic ylides. It was demonstrated that simple ruthenium porphyrins are highly effective catalysts for carbenoid reactions with alkyl allyl sulfides and alkyl allyl amines providing... 

Ring enlargement via an insertion of a carbene generated in the a-position to the ring is an established method and has also been applied to the synthesis of oxepins. The ()3-allylpalladium chloride catalyzed decomposition of substituted ethyl diazo(4/7-pyran-4-yl)acetates in benzene at room temperature gives ethyl oxepin-4-carboxylates 1 in excellent yield.190 The ester function can be replaced by the phosphonate group and other P = 0-functions (see Houben-Weyl,... 

A solution of ethyl diazo(2,4,6-trimethyl-4//-pyran-4-yl)acetate (0.47 g, 2.0 mmol) in benzene (50 mL) was stirred with // -allylpalladium chloride dimer (15 mg) for 2h at rt, and then the solvent was evaporated. The residue was chromatographed (80-g basic alumina, EtOAc/hexane 1 2) yield 0.40 g (97 %) yellow oil. 

ETHYL DIAZOACETATE (Acetic acid, diazo-, ethyl ester)... 

Reactions of carbenoids with 4-thio-substituted 2-azetidinones have attracted much interest recently. Insertion of the carbene unit derived from diazomalonic esters 297-34°> or ethyl diazo(diethoxyphosphoryl)acetate 340 into the C4—S bond of simple P-lactams 353 and 354 took place irrespective of whether a N—H or a N—R... 

Diazabicyclo[2.2.2]octane, 92 Ethyl (Z)-3-bromoacrylate, 130 Ethyl diazo(lithio)acetate, 230 Meldrum s acid, 172 Trimethylsilyl trifluoromethanesulfo-nate, 329... 

Chromium carbene complexes, 82 Ethyl diazo(lithio)acetate, 230 Reformatsky reagent, 348 Titanium(IV) chloride, 304 By other reactions Di- p.-carbonylhexacarbonyldicobalt, 99... 

In contrast to the carbene and carbenoid chemistry of simple diazoacetic esters, that of a-silyl-a-diazoacetic esters has not yet been developed systematically [1]. Irradiation of ethyl diazo(trimethylsilyl)acetate in an alcohol affords products derived from 0-H insertion of the carbene intermediate, Wolff rearrangement, and carbene- silene rearrangement [2]. In contrast, photolysis of ethyl diazo(pentamethyldisilanyl)acetate in an inert solvent yields exclusively a ketene derived from a carbene->silene->ketene rearrangement [3], Photochemically generated ethoxycarbonyltrimethyl-silylcarbene cyclopropanates alkenes and undergoes insertion into aliphatic C-H bonds [4]. Copper-catalyzed and photochemically induced cyclopropenation of an alkyne with methyl diazo(trimethylsilyl)acetate has also been reported [5]. 

DIAZOACETATE (ESTER) SERINE see ASA500 DIAZO-ACETIC ACID ESTER with SERINE see ASA500 DIAZOACETIC ACID, ETHYL ESTER see DCN800 DIAZOACETIC ESTER see DCN800 N-DIAZOACETILGLICINA-IDRAZIDE (ITALIAN) see DC0800... 

Diazo-acetic Esters. —Mercuric oxide dissolves in the cooled ethyl ester of diazo-acetic acid, and the product is extracted with ether. From the ethereal solution yellow, rhombic crystals of mercury bis-diazo-aceiic ethyl ester are deposited, the parameters of which are a b c=0-4546 1 0-72527. The crystals melt with decomposition at 104° C., and are affected by direct sunlight, mercury separating out. The substance explodes on concussion and is volatile in steam, with some decomposition. 

Diazo(trialkylsilyl)acetates 1 can be prepared conveniently from an alkyl diazoacetate and a trialkylsilyltriflate in the presence of a tertiary amine (path A). Furthermore, metalation of ethyl diazoacetate with butyllithium at — 110 °C, followed by addition of chlorotrimethylsilane provides ethyl diazo(trimethylsilyl)acetate. Ethyl diazo(trimethylsilyl)acetate and the corresponding trimethylgermyl- and trimethylstannyl- substituted diazoacetate have been prepared from mercury bis(ethyl diazoacetate) and bis(trimethylsilyl-, germyl- or stannyl)sulfide (path B). Ethyl diazo(trimethylgermyl)- and ethyl diazo(trimethylstannyl)acetate were obtained from ethyl diazoacetate and diethylaminotrimethyltin or -germanium (path C). Similarly, the ethyl (trimethylplumbyl)diazoacetate was obtained from bis(trimethylsilyl)aminotrimethyl-lead. 2... 

The thermally induced cyclopropanation of alkenes with silyldiazoacetates is virtually unknown. Silylated diazo esters are thermally rather stable and do not readily decompose to give a carbene under standard laboratory conditions. The only known cyclopropanation of this type, i.e. synthesis of 2 from ethyl diazo(trimethylsilyl)acetate and ethyl acrylate (formation of E- and Z-isomers, no yield given), probably occurs via a pyrazoline intermediate. 

The rhodium- or copper-catalyzed cyclopropanation of furan and its derivatives with diazo-acetic esters,300-302 or ethyl 2-diazopropanoate300 usually leads to a mixture of the 2-oxa-bicyclo[3.1.0]hex-3-ene-e co-6-carboxylate, ring-opened (4Z)-6-oxohexa-2,4-dienoates, and ring-substituted furans. Only with electron-deficient furans methyl furan-2-carboxylates, 2-[( )-2-methoxycarbonylvinyl]furan300 and with benzofuran,301,303 was the cyclopropane product obtained exclusively. Examples 37-40 are representative.300... 

Methods for the synthesis of damascones by cross-aldol reactions and from a-cyclocitral (144) by treatment with ethyl diazo(lithio)acetate or 1-diazo-lithioacetone have been described. Eighteen new sesquiterpenoid theas-pirane derivatives, e.g. (145) and (146), have been prepared from the dehydro-jS-cyclonerolidol epoxide (147). Racemic theaspirane (148) and dihydroedulan (149) have been synthesized by photosensitized oxidation of dihydro-a-ionol (152) via (150) and (151). Other carotenoid-like compounds for which syntheses have been reported include 3/8-bromo-8-epicaparrapi oxide (153), ... 

C-Silylated cyclohexyl diazo esters can be prepared from the appropriate diazo acetates by treatment with TMSOTf and ethyl diisopropylamine in ether at -78 °C (eq A9) ... 

The synthesis of cllastatin constitutes one of the first enantioselective syntheses on an Industrial scale. In 1966, H. NozakI and R. Noyorl Investigated the enantioselective [2 -I-1 ]-cycloaddition of diazo-acetic esters to olefins. From this, Sumitomo developed industrial processes for the preparation of pyrethroids and cilastatin. In the key step, ethyl diazoacetate is decomposed in presence of isobutene at a dimeric, enantio-merically pure copper complex. The resulting ethyl di-methylcyclopropanecarboxyl-ate has an optical purity of 92% ee. 

These compounds are indispensable building blocks for the preparation of labeled cyclopropane- and cyclopropenecarboxyhc acids, as illustrated by the following three examples. In the first case 2,5-dimethylhexa-2,4-diene reacted with ethyl diazo[2- " C]acetate at 120-140 C in the presence of copper powder as a catalyst or at room temperature in the presence of rhodium(II)pivalate to provide a 1 1 cisitrans mixture of ethyl [2- C]chrysanthemates 145 in 30-70% yield. Treatment of this mixture... 

Tezuka s group (Tezuka and Ando, 1985 Tezuka et al., 1986) was able to isolate and characterize the benzenediazo ether of 1-naphthol (6.10). They stirred a solid mixture of the molecular complex 6.9 formed between an a-azohydroperoxide acid and benzene with an excess of 1-naphthol at room temperature in the dark for several hours. The separation of this solid by thin layer chromatography (silica gel, with a benzene-ethyl acetate mixture [9 1] as eluent) afforded the diazo ether 6.10 as a yellow oil in 17 % yield, together with 4- and 2-phenylazo-l-naphthol (6.11 and 6.12, 4% and 42%, respectively), 4-phenylbenzaldehyde (32%), benzoic acid (23%), and traces of other compounds (Scheme 6-6). Higher yields of the diazo ether (up... 

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