A Convenient Synthesis of aapD-butenolide An Organic Chemistry Laboratory Experiment S. T. Vijayaraghavan and T. R. Baiasubramanian' Ramakrishna Mission Vivekananda College, Madras400 004, India Ae.0-butenolides are five-membered unsaturated u-lactones and are referred to as 2(5H)-furanones (I). Certain butenolides exhibit antibacterial (2,3), antifungal ( 4 , 5 ) ,and tumor-inhibitory (6, 7) activities. They find applications as insecticides (a), herbicides (9), and seed and plant growth remlntors 111. . .- ....- - (10. ,- , -, T h e synthesis of 3-p-nitrophenyl, 4-p-hromophenyl, 2r.SHLfuranone (2). hv a simole and convenient route in the laboratory, is the subject of this communication. This compound can be prepared easily from p-nitrophenylacetic acid and 2,4'-dibromoacetophenone using triethylamine. The reaction consists of two steps taking place one after another in the same reaction vessel. T h e first step involves the formation of the phenacyl ester l, and the second step is an intramolecular condensation of the ketoester to the lactone 2 (reaction 1).
the intermediate phenacyl ester 1 can he isolated and characterized by carrying out the esterification in benzene medium. Apart from the interesting mechanism for the conversion of the ketoester to the lactone, the present method avoids the complications of competing condensation reactions hv usina an arvl ketone (13).
Experimentai To 5.5 mmol (1.00 g) of p-nitrophenylacetic acid in a 50-mL Erlenmeyer flask, 30 mL acetone, 2.5 mL of triethylamine (Caution: Noxious uapors. Make transfers of this material in o fume hood) and 5 mmol (1.39 g) of 2,4'-dibromoacetophenone (Caution: Lachrymator: Avoid contact with skin) were added and the reaction mixture was allowed to stand at room temperature for 3 h withoccasional shaking. Then 60 mL of water wasadded, and the mixture was extracted with 75 mL of dichloromethane. The CH.,CI. laver was washed with 2 X 30 mL of 3 M HC1 and 1X 30 m ~ b ~f % N ~ H solution, C O ~ then dried with anhydrous NanSOd. The CH2C12was evaporated to give the furanone, which was further purified by dissolving in 50 mL of benzene and reprecipitation hy the addition of 200 mL of n-hexane. Yield 1.2 g (67%);m.p. 153-155% (with decomposition). IR (KBr): 1750,1520,1350cm-I. NMR: (CDC18,TMS internal standard): 6 5.2 (s, 2H) and 8.5-7 ppm (multiplet, 8H). UV: (CHClj) .A., nm (E): 271 (22078); 306 (17408). Moss Speetmm: mle (% relative abundance): 361 (15), 359 (17),Mt;185 (88),183(100);150 (17),105(4), 86 (7).85 (8),84 (6),83 (6),82 (16),81 (5),80 (9), 79 (3),78 (6),58 (48),57 (33),56 (12).
Literature Cited (1) Rao.Y.S. C h m ~ R s u1976, . 76,625.
Anattractive feature of this synthesis is the fact that it can be completed by the student in a 3-4 h laboratory period as part of an organic chemistry laboratory exercise using simple apparatus like an Erlenmeyer flask and a separatory funnel. In principle, the synthesis can he extended to other substituted 2(5H)-furanones, hut the cyclization step, in all other cases needs -6 h refluxing (12). Even in the present exercise,
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Journal of Chemical Education
(2) Cauallito, C.J. 1n"Modicinal ChernistryW,C. M.Su(er,Ed.; Wilev: NeluYork, 1951; V0l 1,p 221. 13) Nincharn.A. W.:Raphael.R.A.J. Chem.Sor. 1949,118. (4) Aoki, K.: Tokuda, T.; Hoshi, H.; Satake. K.; Funsysms. S. Japan Patent 7328646. 1973. Chem. Abstr. 1974,80,117147~. (5) Dal Pzzo, A: Dansi, A ; Menqhini, E. Chem. Pharm. Bull. 1974,113. (6) Kupehan, S.A.;Eakin,M.A.;Thornas,A. M.J. Med. Chsm. 1971,14,1147. 17) Kupchsn, S. M. Tr0ns.N. Y Aeod.Sei. 1978.32.85. ( 8 ) Siddall, J. B. U. S. Patent 37W694.1972; Chrm. Abslr. 1973,76,13254~. (9) Rabstoek.T.L.;Sell,H . M . J . A m e r . ChemSoc. 1952.74.274. (10) Payno,G.B. US. Patent 3177227. 11965): Chem Abatr. 1965.63.66660. (11) lino, Y.: Tanskas, A ; Yarnashita, K. Agrie. B i d . Cham. 1972,36,2505. 112) vijqvsraghsvsn,S. T.:Ba1asubrarnanian.T. R. '"Synthesis", in press. 113) Srnith.A. B.:Levenherg,P.A.:Jerris,P.J.;Scarborough,R.M..Jr:Wovkulieh.P.M. ', J . Arne?. Chem Sac. 1981,103,1501.
