Ethoxycarbonyl group

Methyl esters 333 that are activated toward decarboxylation by a C-2-ethoxycarbonyl group and tethered by an alkyl chain to an acrylate Michael-acceptor undergo chemoselective S] [2-dealkylation of the methyl ester, decarboxylation and cyclization upon exposure to lithium chloride in DMEU, affording tetrahydropyrans in excellent yield and diastereoselectivity (Equation 142) <1998JOC144>. 

Acyl-, 4-alkoxycarbonyl- and 4-phenylazo-pyrazolin-5-ones present the possibility of a fourth tautomer with an exocyclic double bond and a chelated structure. The molecular structure of (138) has been determined by X-ray crystallography (Table 5). It was shown that the hydroxy group participates in an intramolecular hydrogen bond with the carbonyl oxygen atom of the ethoxycarbonyl group at position 4 (8OCSCII21). On the other hand, the fourth isomer is the most stable in 4-phenylazopyrazolones (139), a chelated phenyl-hydrazone structure. 

The ethoxycarbonyl group was developed for the protection of phosphonates. The derivative is prepared by reaction of tris(trimethylsilyl) phosphite with ethyl chloroformate and can be cleaved by hydrolysis of the ester followed by silyla-tion with bistrimethylsilylacetamide. ... 

H)-diones although the latter appears less probable. Additional factors, such as the cyclization of the first-formed ring-opened products with a 5-ethoxycarbonyl group are often important. ... 

Because the olefin geometry in compound 9 will most certainly have a bearing on the stereochemical outcome of the hydroboration step, a reliable process for the construction of the trans trisubsti-tuted olefin in 9 must be identified. A priori, the powerful and predictable Wittig reaction28 could be used to construct E u, [3-unsaturated ester 10 from aldehyde 11. Reduction of the ethoxycarbonyl grouping in 10, followed by benzylation of the resulting primary alcohol, would then complete the synthesis of 9. Aldehyde 11 is a known substance that can be prepared from 2-furylacetonitrile (12). 

Dibenzo[/>,rf]thiopyrylium tetrafluoroborate (1) reacts with ethyl lithiodiazoacetate at — 120 C to form the diazo compound 2 which, with dimeric ( 3-allyl)chloropalIadium at 20 C, gives ethyl dibenzo[ ,d]thiepin-6-carboxylate (3), via a carbene intermediate.5 Compound 3 is quite stable the ethoxycarbonyl group can be hydrolyzed by alkali and decarboxylated to give the corresponding parent compound 4 in good yield. 

Subsequently it was found140 that ethyl 2-alkyl-1//-azepine-1-carboxylates can be isolated from a mixture of isomeric 1//-azepines by stirring the mixture with potassium hydroxide in ethanol at room temperature. Apparently, this method, which is limited to 2-alkylated azepines, depends on the slower rate of hydrolysis (and subsequent decomposition of the resulting 1H-azepine-l-carboxylic acid) of the sterically hindered 1-(ethoxycarbonyl) group. Although the yields of l//-azepines are poor (4-7%, vide supra), the method provides access to otherwise difficult to obtain, isomerically pure 2-alkyl-1//-azepines. Under the basic hydrolysis conditions aryl 2-alkyl-l//-azepine-1-carboxylates undergo transesterification to the l-(ethoxycarbonyl) derivatives. 

Propenyl)-1,3-dithiane, after lithiation and addition of zinc chloride, reacts with ethyl 2-oxopropanoate to give preferentially the. vvn-adduct37, which is an intermediate in the synthesis of racemic /ra .s-tetrahydro-2,3-dimethyl-5-oxo-2-furancarboxylic acid. It is assumed, that the ethoxycarbonyl group is brought to a pseudoaxial position in the cyclic transition state by the chelating zinc cation. 

A spectroscopic study of the esters (191) and (192) (R=H,Cl,Br,N02,Me0,Me2N) has shown that the C=C, P=0, and C=0 bonds are coplanar with, in (192), a trans arrangement between the benzene ring and the ethoxycarbonyl group. It then becomes easy to explain the dephosphorylation which occurs when such... 

The comparison between the cycloaddition behavior of simple diazoketones and of ethyl diazopyruvate 56 towards the same olefin underlines the crucial influence of the ethoxycarbonyl group attached to the carbonyl function. This becomes once again evident when COOEt is replaced by an acetal function, such as in l-diazo-3,3-di-methoxy-2-butanone 86 with enol ethers and acetates, cyclopropanes rather than dihydrofurans are now obtained 113). ... 

The alkoxycyclopropane 6, bearing the ethoxycarbonyl group, is converted to the ring-opened vinyl ether 7 [7]. (Scheme 3)... 

In an example given in Scheme 51, tricyclic system 331 is generated by cyclocondensation between the ethoxycarbonyl group at C-5 of the triazole ring and the amino group of the substituent at N-l. The process that starts from catalytic reduction of the nitro group in derivative 329 does not stop at amine 330, but the subsequent spontaneous cyclocondensation leads directly to product 331 that is isolated in 60% yield <2002EJM565>. 

Ethyl 3-azido-l-methyl-177-indole-2-carboxylate 361 is prepared in 70% yield by diazotization of amine 360 followed by substitution of the created diazonium group with sodium azide. In cycloadditions with nitrile anions, azide 361 forms triazole intermediates 362. However, under the reaction conditions, cyclocondensation of the amino and ethoxycarbonyl groups in 362 results in formation of an additional ring. This domino process provides efficiently 4/7-indolo[2,3-i ]l,2,3-triazolo[l,5- ]pyrimidines 363 in 70-80% yield (Scheme 57) <2006TL2187>. 

Sekine, M., Mori, H., and Hata, T., Protection of phosphonate function by means of ethoxycarbonyl group. A new method for generation of reactive silyl phosphite intermediates, Bull. Chem. Soc. Jpn., 55, 239, 1982. 

First, 4-chloropyrimidine 86 was treated with phenylacetylene to give alkynylpyrimidine 87 [62], The fact that the Sonogashira reaction proceeded readily at room temperature may be ascribed to the electron-withdrawing effect of the neighboring ethoxycarbonyl group on 86. When heated with ammonia in EtOH, alkynylpyrimidine ester 87 cyclized efficiently to produce pyridyl lactam 88. 

P-Phosphorins having a phenyl residue at C-4 [e.g. (188)] are arylated in the aryl ring by aryldiazonium salts.165 The ethoxycarbonyl group of the A5-phosphorin (189) can be hydrolysed, transesterified, or reduced without destroying the ring system.166... 

The Diels-Alder reaction of ethyl 2-benzoylacrylate (450) with cyclopentadiene was effectively catalyzed by magnesium(II) complexes of bis(oxazolidine) 448 and oxazolidine 449 (equation 134). When the catalysts were prepared in refluxing acetonitrile, adduct 451 was obtained with virtually complete endo selectivity for the ethoxycarbonyl group and up to 87% ee282. 

Commercially available ethyl nitroacetate is an interesting pronucleophile, because it can serve as the synthetic equivalent of either nitromethane or glycine. The ethoxycarbonyl group can also be considered as a protecting group against dialkylation. The allylic alkylation with ethyl nitroacetate did not require an additional base (salt-free conditions). As a consequence of the high acidity of the chirality center a to N, 1 1 mixtures of epimers were formed. 

The more recent 4-azaquinolizin-l-one synthesis by Katritzky etal. (81JCS(P1)1495) appears more versatile. A 2-ethoxycarbonyIpyrylium salt (275 Scheme 134) is allowed to react with the hydrazone of acetophenone or of a p-substituted acetophenone (276). The methyl group of the resulting 1-aminopyridine derivative (277) is acidic and, when treated with potassium carbonate, generates an anion which attacks the ethoxycarbonyl group to afford the 4-azaquinolizin-l-one derivative (278) in good yield. 

The crystal structure of ethyl 4//-thieno[3,2-3]pyrrole-5-carboxylate 55 indicates an ethoxycarbonyl group attached to a planar thieno[3,2-/)]pyrrole ring system <2004AXE2493>. 

Hydrolysis of the hydrazine BOC-protecting group of 90 followed by treatment with sodium hydride gave pyrazolo[4,3-f][l,2,4]triazine-3-one 44 by nucleophilic cyclization onto the 5-ethoxycarbonyl group (Scheme 64) <2006JA5646>. 

The 3-ethoxycarbonyl group in 4//-pyran 63 (R = Me, R1 = Bu) was hydrolyzed on heating with ethanolic potassium hydroxide this procedure with analogous 4/f-pyrans 63 (R1 = Me, Ph) was accompanied by decarboxylation.107 Acid 607d obtained by hydrolysis of ethyl ester 68 (X = EtO Y = Me) did not decarboxylate to a definite product on heating with copper powder. ... 

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