2011) 1( 24المجلد مجلة ابن الھیثم للعلوم الصرفة والتطبیقیة ارثرواسكوربیك-Dبتیورات لحامض ر مشتقات من الباتحضیر 2010أیلول 15:استلم البحث في 2010تشرین الثاني 9 :قبل البحث في رمیز رسمیة محمود، انباسمة محسن سرح، در مخلصعبد الجبار عبد القا بغداد جامعة ، ابن الهیثم-كلیة التربیة، قسم الكیمیاء لخالصةا ه المشـتقات ذللحصـول علـى هـ.ارثرواسـكوربیكD-تحضیر مشتقات جدیـدة مـن البـاربتیورات لحـامض ا البحثذیتضمن ه مـادة )3(ربیك حـامض االسـكو L-التـي حضـرت مـن تفاعـل ) 4(حـامض االسـكوربیك L--ایزوبروبیلیدینO--6,5تم اختیار C-3 و C-2تمــت اسـترة مجـامیع الهیدروكســیل فـي المواقـع . مـع االســیتون الجـاف بوجـود غــاز كلوریـد الهیـدروجین اولیـة ) 5(التحلـل المـائي للمركـب ). 5(تـم الحصـول علـى المركـب ،اذزیادة من كلورید البنزویل بوجود البیریـدین الجـاف عمالباست ببرایـودات الصــودیوم لینــتج ) 6(بعــدها تمــت اكسـدة المركــب ). 6(اعطــى المركـب ،اذ %)65(حــامض الخلیـك المعباسـت ــات بوجــود هیدروكســید البوتاســـیوم لیعطــي المالونــات ذالــ) 7(االلدیهایــد ائي مثیــل المالونـ ان تفاعـــل ). 8(ي یتفاعــل مـــع ثنــ علــى ) 11(و ) 10(و ) 9(د اعطـى المركبــات مــع الیوریــا والثایویوریـا والكوانــدین هایدروكلورایــ) 8(التكـاثف الحلقــي للمركـب . التوالي (FTIR)واطیــاف االشـعة تحـت الحمــراء TLC)( طة كروماتوغرافیـا الطبقـة الرقیقـةاشخصـت المركبـات المحضـرة بوســ نـوويواطیـاف الـرنین ال U.V-Vis)( طة اطیاف االشعة فوق البنفسجیة والمرئیـةاه المركبات تم تشخیصه بوسذوبعض من ه ) ( المغناطیسي 1HNMR 13).(واطیاف كاربون الرنین النووي المغناطیسيCNM R .اتنالمالو ، حامض االسكوربیك، ثرواسكوربیكحامض االر ، الباربتیورات :لمفتاحیةاالكلمات IBN AL- HAITHAM J. FOR PURE & APPL. SCI. VOL.24 (1) 2011 Synthesis of Barbiturate Derivatives of D-Erythroascorbic Acid Received in : 15 September 2010 Accepted in : 9 November 2010 A-J.A. Mukhlis, B. M. Sarhan, R. M. Rumez Department of Chemistry , College of Education- Ibn-Al-Haitham , University of Baghdad Abstract The aim of this work is the synthesis of new derivatives of barbiturate of D-erythroascorbic acid. To obtain these derivatives, the 5,6-O-isopropylidene-L-ascorbic acid (4) was chosen, which was prepared from the reaction of L-ascorbic acid (3) as a starting material with dry acetone in the presence of hydrogen chloride. The esterification of hydroxyl groups at C-2 and C-3 positions with excess of benzoyl chloride in dry pyridine was obtained compound (5). Hydrolysis for compound (5) in acetic acid (65%) gave the compound (6). Oxidation of the product (6) with sodium periodate results an Aldehyde (7), which was reacted with dimethyl malonate in the presence of potassium hydroxide to give the malonate (8). The cyclocondensation reaction for compound (8) with urea, thiourea and guanidine hydrochloride gave the following compounds (9), (10) and (11) respectively. All these compounds were characterised by Thin Layer Chromatography (TLC) and FTIR spectra and some were characterised by (U.V-Vis) spectra, 1 HNMR spectra and 13 CNM R spectra. Key words: barbiturate, erythroascorbic acid, ascorbic acid, malonate. Introduction Barbituric acid was discovered in the mid-19th century, with the first medical barbiturate, barbitone (1), being synthesized in 1903. Phenobarbitone (2) was introduced as a pharmaceutical in 1912. Therapeutically, these drugs are used as sedatives, anaesthetics and anticonvulsants. Phenobarbitone is also used in the treatment of epilepsy[1]. Most of the known barbiturate compounds possess low solubility in water, therefore, researches claimed synthesis of new carbohydrate derivatives containing barbiturate,[2],[3] these derivatives have high solubility in water in addition of possessing possible biological activity. Khalafi-Nezhad et al.[4] prepared barbituric acid derivative from reaction barbituric acid with different aromatic aldehyde on basic alumina was performed in a conventional microwave oven in the absence of solvent. Recently, Kidwai et al.[5] reported the preparation of barbituric acid derivatives by heating reactants with microwave irradiation and confirm all the compounds synthesized were found to possess good antifungal activity. (1) (2) N N O OO H H C H 2CH 3 C H2C H3 N N O OO C6H 5 H H CH2CH3 IBN AL- HAITHAM J. FOR PURE & APPL. SCI. VOL.24 (1) 2011 Experimental Melting points were determined by electrothermal Stuart melting point apparatus and are uncorrected. IR spectra (in KBr) were recorded on Shimadzu FT infrared spectrophotometer. 1 H and 13 CNM R spectra were recorded on Ultra Shield (300 MHz) spectrophotometer with tetramethyl silane as internal standard. Electronic spectra were obtained using a (U.V-Vis) spectrophotometer type Shimadzu, (160A).Thin layer chromatography (TLC) was performed on aluminum plates coated with layer of silica gel, supplied by Merck. The spots were detected by iodine vapor. Synthesis of 5,6-O-isopropylidene-L-ascorbic acid (4) Dry hydrogen chloride was rapidly bubbled with stirring for 20 minutes into a (250ml) flask containing (10g, 57mmol) of powdered L-ascorbic acid (3) and (100ml) of dry acetone. After addition of (80ml) n-hexane, stirring and cooling in an ice-water, the supernatant was decanted. The precipitate was washed four times with (154ml) of acetone-hexane mixture (4:7) (v/v), cooling in an ice-water and removal of supernatant after each addition. The last precipitate was dried under reduced pressure to give (4) (11.7g, 95.35%) as a white crystalline residue, m.p (206-208˚C). Rf (0.68) (benzene: methanol, 5:5) (v/v). FTIR (KBr, cm -1 ): 3240, 3062 (O-H), 2993 (C-Hali.), 2908 (C-Hace.), 1751 (C=Olac.), 1662 (C=C), 1431 (-CH-asy m), 1388 (-CH-sym), 1141-900 (C-O), 767 δ(O-H) (O.O.P.). Synthesis of 2,3-O-dibenzoyl-5,6-O-isopropylidene-L-ascorbic acid (5) To a cold solution of (4) (10g , 46mmol) in pyridine (50ml), benzoyl chloride was added as drop wise (15ml , 129mmol) with stirring .The resulting mixture was stirred for 2 hours , then kept in dark place at room temperature for 22 hours. The mixture was poured into ice-water and stirred for 20 minutes, the supernatant was decanted. Extraction with chloroform (150 ml). The chloroform layer was washed with water, dilute hydrochloric acid (5%) (2 × 100ml.), water, saturated aqueous sodium hydrogen carbonate (100ml) and water. Dried over anhydrous magnesium sulfate. Chloroform was evaporated gave a brown syrup. The syrup was precipitated from chloroform: petroleum ether (60-80˚C) (1:5) (v/v) to give (5) (15g, 76.5%) as a pale brown solid, m.p (83-85˚C). Rf (0.73) (benzene: methanol, 5:5) (v/v). FTIR (KBr, cm -1): 3062 (C-Har.), 2985 (C-Hali.), 2931 (C- Hace.), 1751 (C=Olac.), 1662 (C=Oest.), 1627 (C=Cali.), 1600 (C=Car.), 1261-1118 (C-O), 900- 600 δ(C-H) (O.O.P.). Synthesis of 2,3-O-dibenzoyl-L-ascorbic acid (6) Compound (5) (10g , 23.6mmol) was dissolved in (65%) acetic acid (30ml) , absolute methanol (10ml) and stirred for 48 hours at room temperature. The TLC showed that the reaction was complete (benzene: methanol, 6:4). Benzene (40ml) was added to the solution and evaporated the organic solvent (repeat this process four times).The residue was solid, recrystallized from chloroform and then diethyl ether to yield (6) (7g, 77.7%) as a white crystals, m.p (115-116˚C), Rf (0.35). FTIR (KBr, cm -1): 3406 (O-H), 3074 (C-Har.), 2939 (C-Hali.), 1716 (C=Oest.), 1600 (C=Car.), 1273-1118 (C-O), 900-600 δ(C-Har.) (O.O.P.). Synthesis of pentulosono-γ-lactone-2,3-enedibenzoate (7) To the stirred solution of sodium periodate (5.6g) in distilled water (60ml) at (0˚C), a solution of (6) (10g, 26mmol) in absolute ethanol (60ml) was added drop wise. After 15 minutes, ethy lene glycol (0.5ml) was added as drop wise, stirring was continued at room temperature for 1 hour. The mixture was filtered and water (40ml) was added to the filtrate. Extraction with ethy l acetate (3×50ml), the extracts dried by anhydrous magnesium sulfate. Evaporation and the residue recrystallized from benzene to yield the pure product (7) (4g, 44.4%) as a white crystals, m.p (110-112˚C). Rf (0.63) (benzene: methanol, 6:4) (v/v). FTIR (KBr, cm -1 ): 3080 IBN AL- HAITHAM J. FOR PURE & APPL. SCI. VOL.24 (1) 2011 (C-Har.), 2839, 2677 (C-Hald.), 1689 (C=Oald.), 900-600 δ(C-Har.) (O.O.P.). 1 HNMR (CDCl3): δ(4.97) ppm (s, 1H, H4), δ (7.28-8.17) ppm (m, 10H, aromatic), δ(11.4) ppm (br, 1H, CHO.). 13CNM R (CDCl3): δ(172.44) ppm (C=O), δ(133.83) ppm (C-3), δ(133.47) ppm (C-2), δ(130.23-128.03) ppm (Car.), δ(77.46) ppm (C-4). The signal of aldehydic carbonyl was disappeared due to it which showed out of the scale.[6] Synthesis of 5-C-dimethyl malonyl-pentulose-γ-lactone-2,3-enedibenzoate (8) The mixture of potassium hydroxide (1.9g, 34mmol) and dimethyl malonate (3.9ml, 34mmol) was stirred for 30 minutes, a solution of (7) (10g, 28.4mmol) in absolute ethanol (60ml) was added. After stirring for 24 hours at room temperature, the TLC showed that the reaction was complete (benzene: methanol, 4:6) and the resulting mixture was filtered then the solvent was evaporated, the combined residue was washed with chloroform and then petroleum ether (60- 80˚C) to give (8) (10g, 72.7%) as a white crystals, m.p (dec.240˚C), Rf (0.65). FTIR (KBr, cm-1): 3402 (O-H), 3055 (C-Har.), 2904 (C-Hali.), 1720 (C=Oest.), 1581 (C=Cali.), 1450(C=Car.), 1400-1000 (C-O), 900-600 δ(C-Har.) (O.O.P.). 1HNMR (DM SO): δ(2.50) ppm (DM SO), δ(2.72) ppm (d, 1H, CH malonate), δ(3.16) ppm (s, 1H, OH), δ(3.56-3.58) ppm (s, 6H, 2CH3 malonate), δ(7.14-8.86) ppm (m, 10H, aromatic). 13CNM R (CDCl3): δ(168.82) ppm (C=O), δ(135.26) ppm (C-3), δ(131.55) ppm (C-2), δ(129.58,128.40) ppm (Car.), δ(51.63) ppm (C-4), δ(44.67) ppm (C-5), δ(40.78-39.11) ppm (C-6 and carbon 2CH3 malonate). Synthesis of pentulose-γ-lactone-2,3-enedibenzoate barbituric acid (9) or thiobarbituric acid (10) or azhydrobarbituric acid (11) To the solution of sodium methoxide (30.9mmol of sodium metal dissolved in absolute methanol (20ml)), dry urea or thiourea or guanidine hydrochloride (15.5mmol) was added, stirring at room temperature for 1 hour. The compound (8) (5g, 10.3mmol) in absolute methanol (30ml) was added, stirring was continued at room temperature for 48 hours. The TLC showed that the reaction was complete (benzene: methanol, 4:6). The solvent was evaporated; the combined residue was washed with hot absolute ethanol to give (9), (10), and (11) respectively. The physical properties for prepared compounds showed in Table (1). The FTIR, 1HNMR and 13CNM R spectra data are given in Tables (2), (3) and (4). Results and Discussion L-ascorbic acid (3) is one of the natural antioxidant present in biological system because of its activity to attack the free radicals and other reactive oxygen species, as the literatures points to the great role which ascorbic acid plays to prevent a number of disease and its importance in food industry.[7],[8] One strategy allows the synthesis of compounds (9), (10) and (11) in (6) steps starting from L-ascorbic acid, scheme (1). The first step employs the protection of the hydroxyl groups at C-5 and C-6 positions in L- ascorbic acid with acetal formation leading to compound (4) using dry acetone in acidic media, following Salomon[9] method. This is followed by esterification of the hydroxyl groups at C-2 and C-3 positions with excess of benzoyl chloride in dry pyridine. The FTIR spectra for compound (4) and (5) were confirmed the formation of compound (5) by disappearance of the bands for (O-H) of compound (4) and exhibited the band at (1662) cm -1 for (C=O) of the ester in compound (5) spectrum. In order to p repare aldehyde (7), the acetal moiety was cleaved under acidic condition[10] (65% acetic acid) for compound (5) to give (6) and oxidation of the product with sodium periodate to result (7), which gave a positive Tolen’s test by the formation of a silver mirror.[11],[12] The FTIR spectra for compound (6) and (7) confirmed the formation of compound (7) by disappearance of the bands for (O-H) of compound (6) and exhibited the band at (1689) cm -1 for (C=O) in compound (7) spectrum. The structure of (7) was confirmed IBN AL- HAITHAM J. FOR PURE & APPL. SCI. VOL.24 (1) 2011 by 1 HNMR which exhibited a signal at δ(11.4) ppm for (CHO) and was characterised by 13CNMR and (U.V-Vis) spectrum which showed one peak at (295) nm (33898 cm-1) (εmax = 156 molar-1cm-1) assigned to (n π*) transition. The other step was the formation of compound (8) from the reaction of an aldehyde (7) with dimethyl malonate. The FTIR spectrum of (8) showed the bands at (3402) cm-1 and (1720) cm -1 due to (O-H) and (C=O) of the ester respectively and disappearance of the band for (C=O) aldehydic. The structure of (8) was confirmed by the disappeared of a signal at δ(11.4) ppm for (CHO) by 1HNMR and was characterised by 13CNM R and (U.V-Vis) spectrum which showed one peak at (297) nm (33670 cm-1) (εmax = 102 molar-1cm-1) assigned to (n π*) transition. In order to obtain our target compounds (9), (10) and (11), the cyclocondensation reaction of malonate (8) with urea, thiourea and guanidine hydrochloride in alkaline media (sodium methoxide) leads to these compounds. All FTIR spectra for these compounds exhibited disappearance of the band at (1720) cm -1 for (C=O) of the ester for compound (8) and displayed of the bands at (1662, 1597, 1643) cm-1 due to (C=O in CHCONH) for compounds (9), (10) and (11) respectively. The FTIR spectra of (9), (10) and (11) showed the bands at (1627) cm -1, (1153) cm-1 and (1597) cm-1 due to (C=O in HNCONH), (C=S) and (C=N) respectively. The structures of these compounds were confirmed by 1HNMR and 13CNM R, which showed disappearance of the signals at δ(3.56-3.58)ppm and δ(40.78-39.11) ppm from 1HNMR and 13CNM R spectra for compound (8). The (U.V-Vis) spectra data are given in Table (5). O O OHHO HO HO (3) O O O OH3C H3C HO OH (4) O O O OH3 C H3C (5) OBzBzO O O HO HO (6) OBzBzO O O OBZ BZO C H O (7) O O OBZBZO HO HC CO2CH3 CO2 CH3 (8) NHHN OO X O O OBZBZO HO Acetone HCl(g) BzCl Py. AcOH 65% NaIO4CH2(CO2CH3)2 KOH Urea or thiourea or guanidine hydrochloride CH3ONa (9), X = O (10), X = S (11), X = NH 1 23 4 5 6 Scheme (1) the scheme of prepared compounds IBN AL- HAITHAM J. FO R PURE & APPL. SCI. VO L.24 (1) 2011 References 1. Cole, M. D. (2003) “The Analysis of Controlled Substances”, John Wiley and Sons, Ltd. Chapter 9: 139,140. 2. Al-Qase, A. H. J.(2000) M . Sc. Thesis, College of Education / Ibn-Al-Haitham, University of Baghdad 3. Fayad,A. A. (2008)Ph. D. Thesis, College of Education / Ibn-Al-Haitham, University of Baghdad 4. Khalafi-Nezhad ,A. and Hashemi,A. (2001) “Microwave Enhanced Knoevenagel Condensation of Barbituric Acid with Aromatic Aldehydes on Basic Alumina”, Iran. J. Chem. & Chem. Eng. 20 (1):9-11. 5. Kidwai,M. ; Thakur ,R. and Mohan,R. (2005) “Ecofriendly Synthesis of Novel Antifungal (Thio) Barbituric Acid Derivatives” Acta Chim. Slov., 52: 88-92. 6. Carey, F. A. (2006) “Organic Chemistry”, 6th Ed., the McGraw-Hill Companies, Inc., New York, pp. 767. 7. Beifuss,U.; Kunz ,O. and Aguado,G. P. (1999) Synlett, 147-149. 8. Beifuss,U. ; Kunz ,O. and Voss, G. (2000 )“Regioselective Synthesis of 3-O-Alkyl Ethers of Ascorbic Acid without Protecting Groups in a Single Step”, Tetrahedron, , 56:357- 363. 9. Salomon,L. L. (1963) Experientia, , 19 (12): 619. 10. Gazivoda,T.; Wittine, K.; Lovric,I. ; Makuc, D.; Plavec, J.; Cetina, M. ; Mrvos-Sermek, D.; Suman,L. ; Kralj,M.; Pavelic, K. ; Mintas ,M . and Raic-Malic S. (2006)“Synthesis, structural studies, and cytostatic evaluation of 5,6-di-O-modified L-ascorbic acid derivatives”, Carbohydr. Res., , 341 (4):433-442. 11. Vogel, A. I. (1989) “Vogel's Textbook of Practical Organic Chemistry”, 5 th Ed., John Wiley and Sons, Inc., New York, , pp. 1219. 12. Fieser ,L. F. and Williamson,K. L. (1983) “Organic Experiments”, 5 th Ed., D. C. Heath and Company, the United States of America, , pp. 160-161. Table (1) :Physical properties for prepared compounds (9), (10) and (11) Comp . No. Formula Molecular weight (g/mol) Weight of product (g) Yield % M.p˚C or dec. Physica l state Rf 9 C23H16O10N2 480 3.57 72 210(dec.) White solid 0.52 10 C23H16O9N2 S 496 3 60 225(dec) Yellow solid 0.60 11 C23H17O9N3 479 4.25 86 205(dec.) Pale- yellow solid 0.33 IBN AL- HAITHAM J. FO R PURE & APPL. SCI. VO L.24 (1) 2011 Table (2): Infrared spectra data (wave number ύ) cm -1 of the compounds (9), (10) and (11) Compound υ(N-H) and υ(O-H) υ(C=O) in (CHCONH, HNCONH) υ(C=N) υ(C-N) υ(C=S) 9 3471(s) 1662(s) 1627(s) - 1346(w) - 10 3383(s) 1597(s) - 1392(s) 1153(m) 11 3421(br) 1643(m) 1597(s) 1334(w) - Where: s = strong, m = medium, w = weak, br = broad Table (3): 1 HNMR data for the compounds (9), (10) and (11) measured in D2O with tetramethyl silane (TMS) as internal standard and chemical shift in ppm (δ) Compound Functional group δ(ppm) 9 d, 1H, CH malonate 3 d, 1H, lactone ring H4 4.70-4.78 m, 10H, aromatic 7.25-7.73 10 d, 1H, CH malonate 3 t, 1H, CH-OH 3.22 d, 1H, lactone ring H4 4.69 m, 10H, aromatic 7.32-7.76 11 d, 1H, CH malonate 3 t, 1H, CH-OH 3.23 d, 1H, lactone ring H4 4.70-4.78 m, 10H, aromatic 7.34-7.77 IBN AL- HAITHAM J. FO R PURE & APPL. SCI. VO L.24 (1) 2011 Table (4): 13CNMR data for the compounds (9), (10) and (11) measured in CDCl3 and chemical shift in ppm (δ) Compound Functional group δ(ppm) 9 C=O in HNCONH 177.53 C=O in CHCONH 175.65 C=O in ester, lactone ring 164.53 C-3 136.14 C-2 131.63 C, aromatic 131.24-127.85 C-4 61.24 C-5, C-6 47.85 10 C=O 161.70 C-3 136.00 C-2 131.20 C, aromatic 128.73, 128.25 11 C=NH 177.43 C=O in CHCONH 175.76 C=O in ester, lactone ring 163.31 C-3 136.18 C-2 131.25 C, aromatic 128.75, 128.29 C-4 48.88 C-5, C-6 47.71 Table (5): Electronic spectra data for the compounds (9), (10) and (11) Compound λmax nm Wave number cm-1 εmax molar-1cm-1 Assignment 9 294 34013 66 n π* 10 257 291 38910 34364 140 195 π π* n π* 11 232 297 43103 33670 15 192 π π* n π*