The condensation of ethyl chloroarylpyruvate (Ⅰ) with ethyl malonate in the presence of sodium ethoxide afforded γ-aryl-α,β-dicarbethoxy-⊿(β),γ-butenolide. On the basis of the chemical and spectral evidences, the structure of the product (II) has been elucidated. This reaction provides new routes to α,β-dicarboalkoxy-γ-butyrolactones and/or to γ-ketocarboxylic acids

Takeda, Akira

Uno, Takaaki

Wada, Satosi

Okayama University Scientific Achievement Repository

MEMOIRS OF THE SCHOOL OF ENGINEERING, OKAYAMA UNIVERSITY, Vol. 2, No.1, APRIL, 1967Lactone Carboxylic Acids. IV.Reaction of Ethyl Chloroarylpyruvate with Ethyl Malonate*Akira TAKEDA, ** Satosi WADA, and Takaaki UNODepartment of Industrial Chemistry(Received December 28, 1966)The condensation of ethyl chloroarylpyruvate 0) with ethyl malonate in thepresence of sodium ethoxide afforded 'l-aryl·a,,B-dicarbethoxy-d.B,Y-butenolide.On the basis of the chemical and spectral evidences, the structure of the product(II) has been elucidated. This reaction provides new routes to a,,B-dicarboalkoxy-'l'-butyrolactones and/or to 'l'-ketocarboxylic acids.It has already been reported that the reactionof ethyl bromopyruvate with l3-ketoesters, i. e.,ethyl oxalacetate, in the presence of sodium,affords corresponding furancarboxylic acids as aresult of O-alkylationl), whereas the reaction ofhalogenopyruvic esters with carbanions has notbeen fully investigated.The pre_ ent paper describes and discusses theresult of the title reaction attempted for thediscovery of a new preparative method of y-butyrolactones, as is exemplified by the reactionof ethyl chlorophenylpyruvate (I, R = H) withethyl malonate (Chart I).Chart IH2 (Pd-C)Itr!1) KOH2) +H30'"(IV)(V)"" Presented at the 19 th Annual Meeting of theChemical Society of Japan, Yokohama, Japan, April2, 1966.** Change of place after April 1, 1967. For reprints:Department of Synthetics Chemistry, School of Engi-neering, Okayama University.80Reaction of Ethyl Chloroarylpyruvate with Ethyl Malonate 81Ethyl chloroarylpyruvate (I) as a starting ma-terial was prepared from the appropriate aroma-tic aldehyde and ethyl dichloroacetate followingthe method of McDonald and Schwab2). Thereaction of ethyl chlorophenylpyruvate (I, R=H) with ethyl sodiomalonate yielded an oilyproduct, which distilled at 204-208° (2.5 mm.)and gave analytical values corresponding wellwith the proposed structure (II, R = H). Thepre5ence of r-lactone ring, ester groups and adouble bond in the structure of II is confirmedby IR absorption bands at 1780cm.-1, 1745cm.-1and 1645cm.-1, respectively (Fig. Ib). The UVabsorption spectra, which had maxima values at218 m,u (e 7,600), 275 m,u (e 8,200) and 330 m,u(e 5,100), also support the structure, since thebands at 275 m/-l and 330 m,u can be attributableto the conjugated system like II.The treatment of II (R = H) with ethanolicpotassium hydroxide, which was followed bythermal decarboxylation in acidic medium, af-forded ethyl benzoylsuccinate (IV), and IV,when heated with dilute sulfuric acid, under-went decarboxylation to form j3.benzoylpropio-nic acid (V).Thin layer chromatographic study revealsthat the degradative hydrogenation of the ozo--nide derived from II (R=H) yielded ethyl a-oxosuccinate as the neutral component. Benzoicacid was detected largely in the acid componentof the degradation product, while both ethylbenzoylacetate and acetophenone were not byany means. Thus, the possible formation ofanother butenolide skeleton in an appreciableamount in the title reaction has been excludedfrom the present consideration.Catalytic hydrogenation of II (R = H) gave anoil (III, R = H), which solidified readily to affordcolorless crystals, m. p. 78-80°, with the em-pirical formula of C;eHJ80 e. The IR spectraobserved for III (R = H) agreed to those ofr -phenyl-a, j3·dicarbethoxybutyrolactone, whichwas prepared from ethyl phenylglycidate anddiethyl malonate by the procedure reported byChelintsev et aP). (Fig. lc).The structure of r.phenyla, j3dicarbethoxy-LJ/I'Y·butenolide has now been assigned to thecondensation product of the title reaction fromthe above-mentioned chemical and spectral evi-dences. Accordingly, it might be assumed asthe possible mechanism of the reaction that theattack of the carbanion derived from malonicester occurred exclusively at the a-position ofthe chloropyruvic ester (I).Yields, and physical and analytical data ofseveral r-aryl-a, j3·dicarbethoxy-LJ/I'Y-butenolidesprepared similarly are listed in Table I.Table I 'l-Aryl-a:, ;9-dicarbethoxy- LJ/I,r-butenolide (II) aR-C = CC02C2H5I IO",/CHC02C2H5CII°R B.p., °c. (mm.) Yield, ____Carbon, %~ ~Hydrogen, %~% Calcd. Found Calcd. FoundCeH5 204-208 (2.5) 32.0 63.15 63.33 5.30 5.59P-CHa,CeH, 210--212 (2.5) 27.7 64.14 63.88 5.70 5.97p-CI-CeH, 218-220 (5) 29.2 56.73 56.86 4.46 4.79a All the compounds listed here are new.Experimental ***Ethyl Chlorophenylpyruvate (1, R=H). -To a mixture of 47.0g. (0.3 mole) of ethyl di-chloroacetate and 31. 8 g. (0.3 mole) of benzalde-hyde dissolved in 150 m!. of anhydrous etherwas added with stirring, in small portions, 25.5g. (0.38 mole) of powdered sodium ethoxide at0°. The reaction mixture, allowed to warm up*** All melting points and boiling points are uncorrected.to room temperature, was refluxed for 1.5 hr.Water was added to dissolve all the depositedsalt. The organic layer was washed severaltimes with water and dried over anhydrousmagnesium sulfate. After the solvent was re-moved in var:uo, the residue was distillatedunder reduced pressure to give 34.8g. (51.1%)of ethyl chlorophenylpyruvate, b. p. 165-167°(18.5 mm.). (IR spectra: Fig. la). Anal. Calcd.for Cl1HuCIOa : C, 58.29; H, 4.85. F01,1nd: C,82 A. TAKEDA, S. WADA snd T. UNO (Vol. 2,58.49; H, 5.10.Other ethyl chloroarylpyruvate (I), obtained similarly, are given in Table II.Table II Ethyl Chloroarylpyruvate (n aR- CH-C-C02C2H5~:l 6RC6H,P-CHa-C6H4P-CI-CBH4B. p., °C. (mm.)165-167 (18.5)161-162 (10)186-188 (20)Yield,%51.143.235.0~Carbon, %~Calcd. Fonnd58.29 58.4959.88 59.6150.60 50.74~Hydrogen,%~Calcd. Found4.85 5.105.44 5.783.87 4.23a All the compounds listed here are new.L--"30;:;';;00---;";;;;OO,.---;';'n;800,.---;'tii600,.----..";;;,,OO--;-:;;"0;;"'0-~100~' ----:::80:::-0--l em-'Reaction of Ethyl Chlorophenylpyruvatewith Ethyl Malonate. - To a solution of so·diomalonate, prepared from 2.3 g. (0.1 mole) ofsodium, 20.0g. (0.125 mole) of diethyI malonate,and 60 m!. of anhydrous ethanol, was addedem-IBOO1l.3g. (0.05 mole) of ethylchlorophenylpyruvate. Thereaction mixture was heatedwith vigorous stirring for 7hr. at 60-65°, which, afteracidification, was extractedwith ether. The etherealextract, washed with satu-rated, aqueous sodium bicar-bonate, and then with water,dried over anhydrous sodi-um sulfate, was evaporatedunder diminished pressure.Distillation of the residueyielded 4.8 g. (32.0 %) ofyellowish oil (II, R= H), b.p. 218-220° (3.5mm.); foranalysis, and IR and U Vmeasurements, the fractionboiling at 204-208° (2.5mm.) was collected at theredistillation. Anal. Calcd.for C16H1606: C, 63.15; H,5.30. Found: C, 63.33; H,5.59.Hydrolysis and Decar-boxylation of II (R=H).-A mixture of 4.2g. (0.075mole) of potassium hydrox-ide dissolved in ethanolcontaining a small amountof water, and 7.5g. (0.025mole) of II (R=H) was keptat room temperature withstirring for 25 hr. The resulted solution, afteracidification with dilute sulfuric acid, was ex-tracted with ether. From the ethere31 extract,1.4 g. of acidic material and 3.8 g. of neutralmaterial were separated in the usual manners.lR spectra of: (a) ethyl chlorophenylpyruvate 0, R=H),liquid film; (b) 'l-phenyl-re, ,8-dicarbethoxy-L1f:l·Y-buteno-Jide (II, R = Hl, liquid film; (c) 'l -phenyl·re, ,8-dicar-bethoxybutyrolactone (Ill, R=H), liquid film, sampled andmeasured while it was an oil (see experimental part);(d) 'l-phenyl.re, ,8-dicarbethoxybutyrolactone (III, R=H),nujol.abcFig. 1.1967) Reaction of Ethyl Chloroarylpyruvate with Ethyl Malonate 83On heating the acidic material in the presenceof potassium hydrogen sulfate, it readily under-went decarboxylation and gave ethyl benzoylsuc-cinate (IV) in good yield. By heating with 10% sulfuric acid for several hours under reflux,IV was transformed to [3-benzoylpropionic acid(V). The neutral component proved to be therecovery of II (R=H). The identification ofthese products, i. e. IV and V, was made bythe comparis:1ll of their IR spectra with those ofthe authentic samplesH ). (IV: IR, 1735 cm.- l(ester II C=O) and 1685cm.- 1 (ketone II C=O);V: IR, 1710 em. -1 (ketone II C = 0) and 1675cm.-1 (acid II C=O».Ozonolysis of II (R= H).- A solution of 1.0g. of II (R=H) in 25 ml. of ethyl acetate wastreated with ozone at -100. The ozonide depos-ited on the wall of vessel was decomposed byhydrogenation in the presence of catalytic amountof Adams' catalyst by the usual procedure.The ethereal extract of the decomposition prod-uct was shaken with sodium bicarbonate solu-tion to remove the acidic component. A neutraloil was obtained after the evaporation of thesolvent. Thin layer chromatograph of the resid-ual oil admixed with 2,4-dinitrophenylhydra-zine showed a prevailing spot at Rf 0.15, whendeveloped by benzene on E. Merck silica-gel G,indicating the preser:ce of ethyl a-oxosuccinateas the major constituent of the ozonolysis prod-uct, although the comparisons practiced wereonly qualitative. The same Rf value as abovewas observed with the 2, 4-dinitrophenylhydra-zone of the authentic sample of ethyl a-oxosuc-dnate under the same condition. Acidificationof the alkaline extract gave benzoic acid (identi-fication: by IR spectra).Hydrogenation of II (R=H). - A solutionof 0.6 g. of II (R = H) in 15 mI. of ethanol washydrogenated in the presence of 0.6 g. of 5 %Palladium-on-carbon under ordinary pressure.After removal of the catalyst and evaporation ofthe solvent in vacuo OAg. of oil (Ill) was obtain-ed. It solidified to give crystals melting at 78- 800 after several recrystallizations from n-hexane. (IR spectra: Fig. 1d). Anal. Calcd.for CnH1BOo : C. 62.74; H, 5.92. Found: C.62.49; H, 6.08.r-Phenyl-a,l3-dicarbethoxybutyrolactone.- This lactone was prepared by the proceduredescribed in literature3l , b.p. 191-1920 (0.5mm.), in 33% yield (lit3). b. p. 225-2270/1 mm.).The product also solidified to white needleswhile storing at room temperature, m. p. 67-680 after recrystallizations from n-hexane.References1) S. ARCHER and M. G. PRATT: J. Am. Chern.Soc. 66, (1944) 1656.2) R. N. McDONALD and P. A. SCHWAB: J. Org.Chern. 29, (1964) 2459.3) G. V. CHELINTSEV and E. D. OSETROVA: J.Gen. Chern. (USSR) 7, (1937) 2373.Palladium-on-carbon catalyzed hydrogenation ofcarbon-carbon double bond in the acidic mediumtends to take stereochemical course of cis addition[e. g., R. L. Augustine: J. Org. Chern. 23,(1958) 1853]. One might assume that III (R=H),which was obtained by the hydrogenation of II (R= H), possesses cis conformation. There are evi-dences from the NMR spectra to support the assump-tion. Discussions and experiments concerning thestructural assignment of these products will bepublished elsewhere.4) W. H. PERKIN: J. Chern. Soc. 47, (1885) 273.5) L. F. SOMERVILLE and C. H. F. ALLEN: Org.Syntheses, Coll. Vol. II, (1943) 81.

Lactone Carboxylic Acids. IV. Reaction of Ethyl Chloroarylpyruvate with Ethyl Malonate

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