Diazoacetoacetate, ethyl

Ethyl 2-diazoacetoacetate, 59, 69 Ethylene, 58, 73 Ethylene bromide, 55, 94 Ethylene carbonate, 58, 97... 

The synthesis of substituted 3,4-dihydrothiopyrans by the reaction of 2-amino-4,5-dihydrothiophene-3-carbonitriles with ethyl diazoacetoacetate involves rearrangement of initially formed 1,4-oxathiocines <96LA725>. 

Rh2(OAc)4 has become the catalyst of choice for insertion of carbene moieties into the N—H bond of (3-lactams. Two cases of intermolecular reaction have been reported. The carbene unit derived from alkyl aryldiazoacetates 322 seems to be inserted only into the ring N—H bond of 323 246). Similarly, N-malonyl- 3-lactams 327 are available from diazomalonic esters 325 and (3-lactams 326 297). If, however, the acetate function in 326 is replaced by an alkylthio or arylthio group, C/S insertion rather than N/H insertion takes place (see Sect. 7.2). Reaction of ethyl diazoacetoacetate 57b with 328 also yields an N/H insertion product (329) 298>, rather than ethyl l-aza-4-oxa-3-methyl-7-oxabicyclo[3.2.0]hex-2-ene-2-earboxylate, as had been claimed before 299). 

A similar carbenoid route to the fused /Mactam 5 involves reaction of ethyl diazoacetoacetate with 4-acctoxyazetidin-2-one (4) catalyzed by rhodium(II) acetate. Rhodium(II) acetate may also promote the cyclizalion step.6 For another route to compounds related to 5 see 8, 36. 37. 

Rhodium(II) catalyzed decomposition of ethyl diazoacetoacetate in thiophene gave no ylide, but only the 2-substituted product (67%) and the cyclopropane (mixture of stereoisomers) (79JCS(Pl)2624). 

A mixture of DL-threonine and DL-allothreonine was prepared by the hydrogenation of ethyl diazoacetoacetate over paltinum oxide in 70% ethanol containing sulfuric acid (eq. 9.90). 2,4-Dimethylpyrrole-3,5-dicarboxylic acid diethyl ester was also obtained as a byproduct. 

A detailed analysis of the reaction of diazoalkanes and a-diazocarbonyl compounds with thiophene has revealed that the formation of stable ylids is observed only with diazomalonic esters (79JCS(P 1)2624). Other a-diazocarbonyl compounds, such as diazoacetic esters, Meldrum s diazo, or ethyl diazoacetoacetate, do not generally give rise to stable ylids. However, with tetrachlorothiophene under favorable conditions, the corresponding ylids may be isolated (84CC190). 

Oxathiocin formation occurs only in very special circumstances when the thiophene ring is substituted with chlorine at the 2- and 5-positions of the ring (88CC138). Reaction of ethyl diazoacetoacetate with 2,5-dichloro-thiophene under rhodium(II) acetate catalysis results in the formation of 2-methyl-3-ethoxycarbonyl-5,8-dichloro-l,4-oxathiocin (26, R = H, R = COjEt, R = CHj) (Scheme 3). In this reaction the intermediate ylid is not observed and the only isolated product is the oxathiocin. However, when diazodimedone (27) is used, the intermediate ylid has been isolated and... 

B. Ethyl diazoacetoacetate. A 2-L, round-bottomed flask equipped with a magnetic stirrer is charged with 26.0 g (0.20 mol) of ethyl acetoacetate, 49.0 g, (0.20 mol) of p-acetamidobenzenesulfonyl azide and 1.5 L of acetonitrile. The reaction vessel Is cooled in an ice bath, and 60.6 g (0.60 mol) of triethylamine is added to the stirring mixture In one portion. The reaction mixture is warmed to room temperature and stirred for 12 hr. The solvent Is removed under reduced pressure, and the residue Is triturated with 500 mL of a 1 1 mixture of ether/petroleum ether. The mixture is filtered to remove the sulfonamide by-product, and the filtrate and wash are concentrated under reduced pressure. The crude product is purified by chromatograpy on silica gel (130 g. Note 5) with ether/petroleum ether (1 4) as eluant to yield 28.5 g (91%) of ethyl diazoacetoacetate as a yellow oil (Note 6). 

C. Ethyl 2-methyl-S-phenyl-3-furancarboxylate A 1-L, three-necked, round-bottomed flask equipped with a magnetic stirrer, an addition funnel, and a reflux condenser is flushed with argon (Note 7). The reaction vessel is charged with 44.35 g of phenylacetylene (0.44 mol. Note 8), 0.38 g of rhodium(ll) acetate dimer (0.00087 mol), and 100 mL of dichloromethane and the mixture is heated to reflux under an argon atmosphere. The addition funnel is charged with 13.57 g of ethyl diazoacetoacetate (0.087 mol) and 200 mL of dichloromethane, and this solution is... 

Ethyl diazoacetoacetate Acetoacetic add, 2-diazo-. ethyl ester (8) Butanoic add,... 

Ethyl acetoacetate, 70, 94 Ethyl bromoacetate, 70, 248 Ethyl diazoacetate, 70, 80 Ethyl diazoacetoacetate, 70, 94... 

The diazo transfer reaction between p-toluenesulfonyl azide and active methylene compounds is a useful synthetic method for the preparation of a-diazo carbonyl compounds. However, the reaction of di-tert-butyl malonate and p-toluenesulfonyl azide to form di-tert-butyl diazomalonate proceeded to the extent of only 47% after 4 weeks with the usual procedure." The present procedure, which utilizes a two-phase medium and methyltri-n-octylammonium chloride (Aliquat 336) as phase-transfer catalyst, effects this same diazo transfer in 2 hours and has the additional advantage of avoiding the use of anhydrous solvents. This procedure has been employed for the preparation of diazoacetoacetates, diazoacetates, and diazomalonates (Table I). Ethyl and ten-butyl acetoacetate are converted to the corresponding a-diazoacetoacetates with saturated sodium carbonate as the aqueous phase. When aqueous sodium hydroxide is used with the acetoace-tates, the initially formed a-diazoacetoacetates undergo deacylation to the diazoacetates. Methyl esters are not suitable substrates, since they are too easily saponified under these conditions. 

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