Synthesis of coenzyme [Q.sub.10].
Abstract: Problem statement: Co[Q.sub.10] is a key compound in ATP synthesis having wide number of health application especially for treating humans suffering from pathophysiological condition. The Co[Q.sub.10] presently available in the market is solely derived from fermentation process. A commercially viable synthetic process is yet to be realized. Approach: The researchers described a new synthetic route for the preparation of Co[Q.sub.10] (1). This new process utilized inexpensive isoprenol as a precursor for the synthesis of an early intermediate with a single isoprene unit. Another key step was the selective oxidation of trans methyl of isoprene unit as a prelude to the expansion of the side chain to decaprenyl group using solanesol. Results: Prenylation of 2, 3-dimethoxy-5-methylhydroquinone using isoprenol in presence of a Lewis acid, followed by selective oxidation of trans methyl group of isoprenyl side chain and subsequent allylic bromination yielded a bromide precursor (7). The p-toluenesulfination of the bromide followed by coupling with solanesyl bromide and de-ptoluenesulfination yielded dimethyl derivative of the Co[Q.sub.10]-quinol. Finally CAN oxidation of dimethyl quinol followed by purification yielded Co[Q.sub.10] in 13% overall yield. Conclusion: The present process achieved Co[Q.sub.10] starting from a relatively inexpensive precursor. Further improvement in the coupling reaction between 8 and solanesyl bromide may lead to a better and viable synthetic process.

Key words: Coenzyme [Q.sub.10], isoprenol, sodium-p-toluenesulfinate
Article Type: Report
Subject: Enzymes (Synthesis)
Enzymes (Physiological aspects)
Enzymes (Research)
Authors: Ravada, Suryachandra Rao
Emani, Lakshma Reddy
Garaga, Machi Raju
Meka, Bharani
Golakoti, Trimurtulu
Pub Date: 04/01/2009
Publication: Name: American Journal of Infectious Diseases Publisher: Science Publications Audience: Professional Format: Magazine/Journal Subject: Biological sciences Copyright: COPYRIGHT 2009 Science Publications ISSN: 1553-6203
Issue: Date: April, 2009 Source Volume: 5 Source Issue: 2
Topic: Event Code: 310 Science & research
Geographic: Geographic Scope: India Geographic Code: 9INDI India
Accession Number: 208275461
Full Text: INTRODUCTION

Coenzyme [Q.sub.10] (Co[Q.sub.10]), a prominent member of the ubiquinone family, is an essential component of the mitochondrial electron transfer chain, which is required for ATP synthesis and functions as an antioxidant in cell membranes and lipoproteins [1]. Co[Q.sub.10] is also a powerful antioxidant not only within the mitochondria but also in other organelle membranes containing CoQ [2]. Co[Q.sub.10] is ubiquitously present in the mammalian tissues, especially in the heart. The fact that the levels of endogenous Co[Q.sub.10] in the heart decreases during ischemic heart disease including heart failure prompted clinical trials with Co[Q.sub.10] in patients that suffered from heart failure [3]. Randomized, double blind, placebo-controlled trials of oral administration of Co[Q.sub.10] have confirmed the effectiveness of Co[Q.sub.10] in improving angina episodes, arrhythmias and left ventricular function in patients with acute myocardial infarction [4].

Co[Q.sub.9] is found in rodents like mice and rats, while Co[Q.sub.6], Co[Q.sub.7] and Co[Q.sub.8], are found in yeast and bacteria [5,6] The majority of Co[Q.sub.9] in rat liver is present in its reduced form (ubiquinol), which exerts its antioxidative function [7]. Similar to Co[Q.sub.10], Co[Q.sub.9] is not merely a compound responsible for energy transduction in mitochondrial membrane in rat heart; it also serves as a functional element in the cells and possesses ability for redox cycling. The Co[Q.sub.9] differs from Co[Q.sub.10] with respect to the number of isoprenoid units in the tail; Co[Q.sub.9] has nine units in contrast to the presence of 10 units in Co[Q.sub.10].

Most of the Co[Q.sub.10] is found in mammalian hearts including human myocardium [7]. Co[Q.sub.10] is not an essential nutrient, because it can be synthesized in the body. High amounts of Co[Q.sub.10] can also be found in several food products, including meat, fish, peanuts and broccoli [8]. Dietary intake of Co[Q.sub.10] is about 25 mg [day.sup.-1], which is inadequate for the body under pathophysiological conditions [2]. A number of methods have been developed for the synthesis of Co[Q.sub.10] [9-26] since the first industrial approach by Hideki Fukawa at Nisshin in 1974 [27].

The researcher describe herein a novel process for the synthesis of Coenzyme [Q.sub.10] as shown in Fig. 1.

[FIGURE 1 OMITTED]

MATERIALS AND METHODS

2, 3-dimethoy-5-methyl-p-benzoquinone and isoprenol were purchased from Sigma-Aldrich Chemie GmbH, Steinheim, Germany. Sodiumdithionate, dimethylsulphate, sodiumborohydride, phosporoustribromide, sodium metal, cericammoniumnitrate were purchased from SD Fine chemicals, TV Industrial estate, Mumbai, India. Selinium dioxide was purchased from Molychem, Souri building, Mumbai, India. All the above chemicals were used as received. Solanesyl bromide was prepared from solanesol, which was isolated from tobacco waste using a known procedure. IR spectra were recorded on a Perkin-Elmer (model spectrum BX) FT-IR instrument in chloroform. [sup.1]H NMR spectra were recorded on Bruker Avance AV 400 MHz Spectrometer and [sup.13]C NMR spectra were recorded on Bruker Avance AV 100MHz Spectrometer. Mass studies were performed on LC-MS system equipped with Agilent 1100 series, LC/MSD detector and 1100 series Agilent HPLC pump. Normal phase silica gel (ACME, 100-200 mesh) was used for column chromatography. Silica gel pre-coated plates (Alugram Sil G/[UV.sub.254]) were used for thin layer chromatography using the solvent system CH[Cl.sub.3]/MeOH (9:1) and visualized by immersing the plate in vanillin sulfuric acid reagent followed by heating at 110[degrees]C.

2, 3-Dimethoxy-5-methyl hydroquinone (2): 2, 3-dimethoxy-5-methylquinone (6 g, 0.0329 mol) and 48 mL of acetonitrile, 12 mL of water and sodium dithionate (8.6 g, 0.0494 mol) were taken in a round bottom flask. Reaction mixture was stirred at room temperature for 2 h. After completion, the reaction mixture was poured in to ice cold water and extracted with EtOAc. The organic layer was washed with brine, dried over [Na.sub.2]S[O.sub.4] and concentrated under vacuum at 40[degrees]C temperature to yield 2 (5.5 g, 90.7%).

2, 3-Dimethoxy-5-methyl-6-prenylquinol (3): A mixture of 2, 3-Dimethoxy-5-methylhydroquinone (2, 5.5 g, 0.0298 mol), 28 mL of carbon tetrachloride and 2-methyl-3-buten-2-ol (4.1 g, 0.0476 mol) was taken in a round bottom flask. Under vigorous stirring, B[F.sub.3] etherate (0.85 g, 0.00597 mol) was added drop wise to reaction mixture at 0-5[degrees]C. Then reaction mixture was allowed to warm up to room temperature and continued the stirring. After 3 h, the reaction mixture was poured into ice cold water and the mixture extracted with EtOAc. The organic layer was washed with brine, dried over [Na.sub.2]S[O.sub.4] and evaporated under vacuum at 40[degrees]C to obtain 3 (8 g, 96.1%).

2, 3, 4, 5-Tetramethoxy-6-prenyl toluene (4): 2, 3-dimethoxy-5-prenyl-6-methyl quinol (3, 8 g, 0.03174 mol) and sodium hydroxide (5 g, 0.125 mol) were dissolved in 21 mL of water in a round bottom flask. Dimethyl sulphate (19.9 g, 0.1587 mol) was slowly added to reaction flask at room temperature and the reaction mixture was stirred at 90[degrees]C for 2 h. After completion, the reaction mixture was poured in to ice cold water, acidified with 5N [H.sub.2]S[O.sub.4] and extracted with EtOAc and the organic layer was washed with brine, dried over [Na.sub.2]S[O.sub.4] and concentrated under vacuum. The residue (9 g) was subjected to column chromatography over silica gel using 2% EtOAc/hexane to yield 4 (6.9 g, 78%).

IR (CH[Cl.sub.3]) [v.sub.max] [cm.sup.-1]: 2933, 1467, 1407, 1350, 1258, 1196, 1100, 1070, 1042, 1015 ; [sup.1]H NMR [delta] (400 MHz, CD[Cl.sub.3]): 4.97 (1H, m), 3.83 (3H, s), 3.82 (3H, s), 3.71 (3H, s), 3.71 (3H, s), 3.23 (2H, d, J = 6.80 Hz), 2.07 (3H, s), 1.70 (3H, d, J = 0.8 Hz), 1.61 (3H, d, J = 0.8 Hz); [sup.13]C NMR [delta] (100 MHz, CD[Cl.sub.3]): 147.88, 147.69, 144.96, 144.72, 131.30, 129.15, 125.25, 122.94, 61.02, 60.99, 60.61, 25.91, 25.63, 17.86, 11.66; LCMS (ESI, positive scan): m/z 303 [(M+Na).sup.+].

2, 3, 4, 5-Tetramethoxy-6-(2-methylbut-2-ene-1-al-4yl)toluene (5) and 2, 3, 4, 5-tetramethoxy-6-(2-methylbut-2-ene-1-ol-4yl)toluene (6): To a solution of 2, 3, 4, 5-tetramethoxy-6-prenyl toluene (4, 7.3 g, 0.06576 mol) in ethanol (100 mL) was slowly added Se[O.sub.2] (32.5 g, 0.2959 mol) at room temperature and the reaction mixture was stirred at room temperature for 4 h. After completion of the reaction, the mixture was poured in to ice water and the mixture was extracted with EtOAc. The organic layer was washed with brine, dried over [Na.sub.2]S[O.sub.4] and concentrated to obtain a mixture of 5 and 6 (5.5 g, 80%). For identification purpose, a small sample (0.5 g) of the mixture was subjected to silica column chromatography using hexane and ethyl acetate mixtures. The fractions eluted with 15% EtOAc/hexane were monitored, identical fractions combined and evaporated to yield 5 (225 mg). Similarly, the fractions eluted with 30% EtOAc/hexane were monitored and identical fractions combined and evaporated to obtain 6 (150 mg).

2, 3, 4, 5-Tetramethoxy-6-(2-methylbut-2-ene-1-al-4yl) toluene (5): IR (CH[Cl.sub.3]) [v.sub.max] [cm.sup.-1]: 2932, 1687, 1467, 1407, 1352, 1219, 1104, 1039; [sup.1]H NMR [delta] (400 MHz, CD[Cl.sub.3]): 9.30 (1H, s), 6.32 (1H, m), 3.84 (3H, s), 3.83 (3H, s), 3.74 (3H, s), 3.72 (3H, s), 3.58 (2H, dd, J = 6.8, 0.8 Hz), 2.07 (3H, s), 1.83 (3H, d, J = 1.2 Hz), [13.sub.C] NMR [delta] (100 MHz, CD[Cl.sub.3]): 195.06, 152.56, 148.07, 147.87, 145.94, 144.88, 138.92, 125.50, 125.28, 61.03, 61.00, 60.96, 60.68, 26.99, 11.93, 9.29; LCMS (ESI, positive scan): m/z 295 [(M+H).sup.+], m/z 317 [(M+Na).sup.+], m [z.sup.-1] 333 [(M+K).sup.+].

2, 3, 4, 5-Tetramethoxy-6-(2-methylbut-2-ene-1-ol-4yl)toluene (6): IR (CH[Cl.sub.3]) [v.sub.max] [cm.sup.-1]: 3432, 2935, 2862, 1466, 1407, 1351, 1219, 1105, 1067, 1039, 1013; [sup.1]H NMR [delta](400 MHz, CD[Cl.sub.3]): 5.26 (1H, m), 3.93 (2H, s), 3.83 (3H, s), 3.82 (3H, s), 3.72 (3H, s), 3.70 (3H, s), 3.29 (2H, dd, J = 6.8, 0.8 Hz), 2.07 (3H, s), 1.76 (3H, s), [sup.13]C NMR [delta] (100 MHz, CD[Cl.sub.3]): 147.93, 147.72, 145.19, 144.75, 134.68, 128.29, 125.23, 124.52, 68.83, 61.02, 60.99, 60.63, 25.51, 13.81, 11.76; LCMS (ESI, positive scan): m/z 319 [(M+Na).sup.+], m/z 335 [(M+K).sup.+].

2, 3, 4, 5-Tetramethoxy-6-(2-methylbut-2-ene-1-ol-4yl)toluene (6): The mixture of 5 and 6 from the previous reaction (5.5 g, 0.01864 mol) was dissolved in 55 mL of ethanol and treated slowly with sodium borohydride (413 mg, 0.01116 mol) at room temperature and the reaction mixture was stirred at room temperature. After 2 h, the reaction mixture was poured into ice cold water, acidified with 5N HCl and extracted with EtOAc. The organic layer was washed with brine, dried over [Na.sub.2]S[O.sub.4] and concentrated under vacuum. The residue (5 g) was subjected to column chromatography over silica using 5,10,15 and 20% hexane/EtOAc mixtures. The product eluted with 15 and 20% mixtures of EtOAc/hexane were monitored, combined and evaporated under vacuum to obtain 6 (3.5 g, 65%).

2, 3, 4, 5-Tetramethoxy-6-(1-bromo-2-methylbut-2-ene-4yl) toluene (7): 2, 3, 4, 5-Tetramethoxy-6-(2-methylbut -2-ene -1-ol -4yl) toluene (6, 2 g, 0.006756 mol) was dissolved in 10 mL of tetrahydrofuran and treated with pyridine (0.1 g, 0.001689 mol). P[Br.sub.3] (0.66 g, 0.002477 mol) was slowly added to the reaction mixture at 0[degrees]C for 15 min. After 30 min, the reaction mixture was poured into ice cold saturated sodium bicarbonate solution and extracted with EtOAc. The organic layer was washed with brine, dried over [Na.sub.2]S[O.sub.4] and concentrated under vacuum. The residue (2.6 g) was subjected to column chromatography over silica gel using hexane and 2% EtOAc/hexane mixtures. The fractions eluted with 2% EtOAc/hexane mixture were combined and evaporated to obtain 7 (2.2 g, 92%).

IR (CH[Cl.sub.3]) [v.sub.max] [cm.sup.-1]: 2934, 1466, 1408, 1351, 1200, 1105, 1073, 1039, 1012, 974; [sup.1]H NMR [delta] (400 MHz, CD[Cl.sub.3]): 5.44 (1H, t, J = 6.8 Hz), 3.89 (2H, s), 3.83 (3H, s), 3.82 (3H, s), 3.72 (3H, s), 3.71 (3H, s), 3.28 (2H, d, J = 6.8 Hz), 2.06 (3H, s), 1.85 (3H, d, J = 0.8 Hz); [sup.13]C NMR [delta] (100 MHz, CD[Cl.sub.3]): 147.95, 147.78, 145.39, 144.78, 131.75, 129.65, 127.36, 125.27, 61.04, 61.02, 60.98, 60.64, 41.48, 26.23, 14.81, 11.77; LCMS (ESI, positive scan): m/z 361 [(M+H).sup.+], m/z 383 [(M+Na).sup.+].

2, 3, 4, 5-Tetramethoxy-6-(1-p-toluenesulphinyl-2-methylbut-2-ene-4yl)toluene (8): But-2-ene-2-methyl-1-bromo-4-yl tetramethoxytoluene (1 g, 0.00277 mol) was dissolved in 10 mL of dry dichloromethane treated with triethylamine (0.28 g, 0.00277 mol). Sodium 4-toluene sulphinate (493 mg, 0.00278 mol) was slowly added in portions wise to the reaction mixture and stirred at room temperature for 3 h. Then the reaction mixture was poured in to ice cold water and acidified to pH 4 with 5N HCl and then extracted with EtOAc. The organic layer was washed with brine, dried over [Na.sub.2]S[O.sub.4] and concentrated. The residue was subjected to column chromatography over silica gel using hexane 5, 10 and 15% EtOAc/hexane mixtures. The fractions eluted with 15% of EtOAc in hexane were monitored and the fractions containing the compound were combined evaporated to afford 8 (1 g, 83.3%).

IR (CH[Cl.sub.3]) [v.sub.max] [cm.sup.-1]: 2933, 1594, 1463, 1410, 1352, 1309, 1212, 1108, 1040, 970; [sup.1]H NMR [delta](400 MHz, CD[Cl.sub.3]): 7.58 (2H, d, J = 8.0 Hz), 7.15 (2H, d, J = 8.0 Hz), 4.85 (1H, t, J = 6.4 Hz), 3.83 (3H, s), 3.80(3H, s), 3.70 (3H, s), 3.63 (3H, s), 3.61 (2H, s), 3.17 (2H, d, J = 6.8 Hz), 2.32 (3H, s), 1.91 (3H, s), 1.86 (3H, d, J = 1.2 Hz); [sup.13]C NMR [delta] (100MHz, CD[Cl.sub.3]): 147.84, 147.63, 145.32, 144.67, 144.29, 135.59, 134.29, 129.40, 128.45, 127.18, 125.13, 123.50, 66.14, 61.00, 60.94, 60.89, 60.61, 26.22, 21.49, 16.98, 11.64; LCMS (ESI, positive scan): m/z 435 [(M+H).sup.+].

Synthesis of 9: 2, 3, 4, 5-Tetramethoxy-6-(1-p-toluenesulphinyl-2-methylbut-2-ene-4yl) toluene (1 g, 0.002304 mol) and solanesol bromide (2.4 g, 0.00345 mol) were dissolved in 10 mL of tetrahydrofuran. Separately, potassium ter-butoxide (520 mg, 0.004634 mol) was suspended in 10 mL of tetrahydrofuran and added dropwise to the above solution containing 2, 3, 4, 5-tetramethoxy-6-(1-p-toluenesulphinyl-2-methylbut-2-ene-4yl)toluene and solanesol bromide at -20[degrees]C. After 30 min, the reaction mixture was allowed to reach ambient temperature and continued the stirring for 2 h. The contents were then poured in to ice water and the mixture was acidified to pH 4 with 5N HCl and extracted with EtOAc. The organic layer was washed with brine, dried over [Na.sub.2]S[O.sub.4] and concentrated under vacuum. The residue was subjected to column chromatography over silica gel by eluting with hexane followed by 2 and 5% EtOAc/hexane mixtures. The fractions eluted with 5% EtOAc/hexane were combined and evaporated to yield 9 (1.78 g, 74%).

IR (CH[Cl.sub.3]) [v.sub.max] [cm.sup.-1]: 2925, 2854, 1597, 1465, 1406, 1383, 1314, 1219, 1145, 1105, 1086, 1041; [sup.1]H NMR [delta] (400 MHz, CD[Cl.sub.3]): 7.57 (2H, d, J = 8.0 Hz), 7.15 (2H, d, J = 8.0 Hz), 5.02 (10H, m) 3.82 (3H, s), 3.79 (3H, s), 3.68 (3H, s), 3.58 (3H, s), 2.32 (3H, s), 1.99 (18H, m), 1.90 (20H, m), 1.85 (3H, s), 1.75 (3H, s), 1.60 (6H, s), 1.51 (15H, s), 1.49 (3H, s); [sup.13]C NMR [delta] (100MHz, CD[Cl.sub.3]): 145.24, 144.67, 138.44, 135.31, 134.93, 134.86, 134.15, 129.52, 129.24, 128.87, 124.44, 124.31, 124.25, 118.79, 73.87, 66.32, 60.94, 60.88, 60.58, 39.74, 26.75, 26.70, 25.62, 21.58, 17.63, 16.28, 15.99, 11.54; LCMS (ESI, positive scan): m/z 1046 [(M+H).sup.+].

2, 3, 4, 5-Tetramethoxy-6-decaprenyltoluene (10): To a solution of 9 (800 mg, 0.7648 mmol) in 8ml of THF was added ethanol (1.23 g, 0.02676 mol). Sodium (146 mg, 10.707 mmol) pieces were slowly added to the reaction mixture under vigorous stirring at room temperature and continued the stirring for 9 h. Then the reaction was quenched by pouring into ice water and the mixture extracted with EtOAc. The organic layer was washed with brine, dried over [Na.sub.2]S[O.sub.4] and concentrated under reduced pressure. The residue was subjected to column chromatography using hexane and 2% EtOAc/hexane. The fractions eluted with 2% EtOAc/hexane mixture were monitored, identical fractions combined and evaporated to obtain 10 (540 mg, 79%)

IR (CH[Cl.sub.3]) [v.sub.max] [cm.sup.-1]: 2963, 2925, 2854, 1665, 1465, 1407, 1382, 1352, 1196, 1105, 1043; 1H NMR [delta] (400 MHz, CD[Cl.sub.3]): 5.04 (10H, t, J = 6.40 Hz), 3.83 (3H, s), 3.83 (3H, s), 3.71 (3H, s), 3.70 (3H, s), 3.20 (2H, d, J = 6.4 Hz), 2.10 (3H, s), 1.99 (20H, m), 1.91 (18H, m), 1.60 (3H, s), 1.52 (3H, s); [sup.13]C NMR [delta] (100 MHz, CD[Cl.sub.3]): 147.88, 147.70, 135.11, 135.03, 134.91, 134.86, 131.16, 129.79, 124.89, 124.45, 124.30, 124.24, 124.15, 123.43, 123.17, 122.92, 61.02, 60.91, 60.60, 60.56, 40.12, 39.74, 39.72, 27.02, 26.80, 25.62, 23.34, 17.63, 16.21, 11.68, 11.54; LCMS (ESI, positive scan): m/z 915 [(M+Na).sup.+].

Coenzyme [Q.sub.10] (1): 2, 3, 4, 5-Tetramethoxy-6-decaprenyltoluene (10, 300 mg, 0.00034 mol) was dissolved in a mixture of 1.25 mL of acetonitrile and 1.25 mL of dichloromethane. Cericammoniumnitrate (560 mg, 0.00102 mole) was slowly added to the reaction mixture at 0[degrees]C followed by 3 mL of aqueous acetonitrile and the reaction mixture was stirred at 10[degrees]C. After 1 h, the reaction mixture was poured in to ice cold water and extracted with EtOAc. The organic layer was washed with brine, dried over [Na.sub.2]S[O.sub.4] and evaporated under vacuum. The residue was subjected to column chromatography over silica gel using hexane and 2% EtOAc/hexane mixture. The fractions eluted with 2% EtOAc/hexane mixture were monitored, the fraction containing the product combined and evaporated to yield Co[Q.sub.10] (1, 210 mg, 72%).

IR (CH[Cl.sub.3]) [v.sub.max] [cm.sup.-1]: 2923, 2853, 1743, 1653, 1611, 1146, 1265, 1201, 1150, 1098, 1023; [sup.1]H NMR [delta] (400 MHz, CD[Cl.sub.3]): 5.04 (10H, t, J = 6.4 Hz), 3.91 (3H, s), 3.90 (3H, s), 3.12 (2H, d, J = 6.8 Hz), 1.99 (20H, m), 1.94 (3H, s), 1.91 (18H, m), 1.60 (6H, s), 1.53 (3H, s), 1.52 (21H, s); [sup.13]C NMR [delta] (100 MHz, CD[Cl.sub.3]): 183.87, 141.71, 138.85, 137.85, 137.62, 135.15, 134.93, 134.86, 131.17, 125.05, 124.64, 124.44, 124.30, 123.87, 118.92, 61.06, 40.02, 39.74, 39.72, 38.35, 32.00, 29.67, 29.32, 27.00, 26.80, 26.75, 26.71, 26.57, 26.36, 25.63, 25.30, 25.15, 232.38, 17.63, 16.00, 15.97, 11.87. 11.82; LCMS (ESI, positive scan): m/z 863 [(M+H).sup.+], m/z 885 [(M+Na).sup.+], m/z 901 [(M+K).sup.+].

RESULTS

The synthesis of Co[Q.sub.10] was carried out in nine steps as shown in Fig. 1. 2, 3-Dimethoxy-5-methylquinone was reduced to 2 with sodium dithionate in 90.7% yield. The reaction of 2, 3-dimethoxy-5-methylhydroquinone (2) with isoprenol in presence of B[F.sub.3] etherate in carbon tetrachloride yielded the prenylated hydroquinone (3) in 96% yield. The di-O-methylation of the hydroquinone using dimethylsulphate yielded 2, 3, 4, 5-tetrametnoxy-6-prenyltoluene (4) in 78% yield. The oxidation of the terminal methyl in the prenyl side chain with selenium dioxide yielded 5 and 6 in 80% overall yield. The mixture of 5 and 6 was subjected to reduction using sodium borohydride to yield the (2E)-4-[2, 3, 4, 5-tetramethoxy-6-methylphenyl] but-2-en-1-ol (6) in 65% yield. The alcohol 6 was converted to the bromide 7 using P[Br.sub.3] in 92% yield and then subjected to p-toluenesulfination using sodium p-toluene sulphinate in dry dichloromethane to give p-toluenesulfinate 8 in 83% yield. The p-toluenesulfinate (8) was nonaprenylated using solanesyl bromide in presence of strong base potassium tert-butoxide to obtain 9 in 74% yield. The reductive de-p-toluenesulfination of 9 using sodium in ethanol yielded 10 in 79% yield. Finally CAN oxidation of 10 in 1:1 mixture of dichloromethane and acetonitrile, followed by column chromatography and crystallization afforded Co[Q.sub.10] (1) in 72% yield.

DISCUSSION

Coenzyme (Co[Q.sub.10]), a member of the ubiquinone family, is an essential component of the mitochondrial electron transfer chain. It is widely being used for cardiac health and also as an antioxidant. It also holds promise as an anticancer agent. The commercial quantities, however, limited as the Co[Q.sub.10] in the market is solely derived from the fermentation technology and the available synthetic methodologies are not commercially feasible. The present study has been an attempt towards the cost viable synthesis of Co[Q.sub.10].

A new synthetic route for the preparation of Co[Q.sub.10] is described. The key steps include prenylation of the substituted quinol moiety with a relatively inexpensive isoprenol and selective oxidation of trans methyl group in the prenylated intermediate to obtain the substituted prenol as an essential precursor for the expansion of the side chain to decaprenyl group. The reaction of 2, 3-dimethoxy-5-methylhydroquinone with isoprenol in presence of B[F.sub.3] etherate yielded the prenylated hydroquinone (3). It was then subjected to di-O-methylation, followed by oxidation of terminal methyl with selenium dioxide to yield a mixture of 5 and 6. The mixture of 5 and 6 without further separation was subjected to sodium borohydride reduction to yield the (2E)-4-[2, 3, 4, 5-tetramethoxy-6-methylphenyl]but-2-en-1-ol (6). The alcohol was converted to the bromide (7) using P[Br.sub.3] and then subjected to p-toluenesulfination. The p-toluenesulfinate (8) was nonaprenylated using solanesyl bromide in presence of a strong base to obtain 9. This advanced intermediate 9 was de-p-toluenesulfinated using sodium in ethanol to obtain the dimethyl derivative of Co[Q.sub.10] quinol. Finally CAN oxidation of 10 was afforded Co[Q.sub.10] (1). The pure Co[Q.sub.10] was isolated from the crude reaction mixture using column chromatography followed by crystallization in 13% overall yielded.

CONCLUSION

Co[Q.sub.10] is a potentially useful compound having wide number of health applications especially those related to cardiovascular diseases. Though the Co[Q.sub.10] from biotechnology process can able to meet the current demand, no commercially viable synthetic process is available. The present process achieves Co[Q.sub.10] starting from relatively inexpensive precursor, called isoprenol. It achieves key synthetic intermediate 8, needed for the expansion of the prenyl chain, through a novel viable process. This is more economical than expanding expensive natural nonaprenyl compound called solanesol by an isoprene unit before coupling to the [Q.sub.0] precursor. This process can also be used to produce other CoEnzyme Q compounds having different number of isoprene units per side chain.

ACKNOWLEDGEMENT

The researchers thank Sri G. Ganga Raju, the Chairman, Mr. G. Rama Raju, Director, Laila Group and Mr B. Kiran, CEO, Laila Nutraceuticals for their encouragement and financial support doing the research study.

REFERENCES

[1.] Ernster, L. and G. Dallner, 1995. Biochemical, physiological and medical aspects of ubiquinone function. Biochim. Biophys. Acta, 1271: 195-204. http://www.ncbi.nlm.nih.gov/pubmed/7599208

[2.] Overvad, K., B. Diamant, L. Holm, G. Holmer, S.A. Mortensen and S. Stender, 1999. Conzyme [Q.sub.10] in health and disease. Eur. J. Clin. Nutr., 53: 764-770. http://www.nature.com/ejcn/journal/v53/n10/abs/1 600880a.html

[3.] Otani, H., H. Tanaka, T. Inoue, M. Umemoto, K. Omoto, K. Tanaka, T. Sato, T. Osako, A. Masuda, A. Nonoyama and T. Kagawam, 1984. In vitro study on contribution of oxidative metabolism of isolated rabbit heart mitochondria to myocardial reperfusion injury. Circ. Res., 55: 168-175. http://circres.ahajournals.org/cgi/content/abstract/5 5/2/168

[4.] Singh, R.B., G.S. Wander, A. Rastogi, P.K. Shukla, A. Mittal, J.P. Sharma, S.K. ehrotra, R. Kapoor and R.K. Chopra, 1998. Randomized, double-blind placebo-controlled trial of coenzyme [Q.sub.10] in patients with acute myocardial infarction. Cardiovase. Drug Ther., 12: 347-353. DOI: 10.1023/a:1007764616025

[5.] Warner, M.G., 2000. Complimentary and alternative therapies for hypertension. Complementary Health. Pract. Rev., 6: 11-19. http://chp.sagepub.com/cgi/reprint/6/1/11

[6.] Matsura, T., K.Yamada and T. Kawasaki, 1992. Difference in antioxidant activity between reduced coenzyme Q9 and reduced coenzyme [Q.sub.10] in the cell: Studies with isolated rat and guinea pig hepatocytes treated with a water-soluble adical initiator. Biochim. Biphys. Acta, 1123: 309-315. http://www.ncbi.nlm.nih.gov/pubmed/1536870

[7.] Folkers, K., S. Vadhanavikit and S.A. Mortensen, 1985. Biochemical rationale and myocardial tissue data on the effective therapy of cardiomyopathy with coenzyme [Q.sub.10]. Proc. Natl. Acad. Sci. USA., 82: 901-904. http://www.pnas.org/content/82/3/901.abstract

[8.] Dallner G. and Stocker R., 2005. Coenzyme Q. Encyclopedia of Dietary Supplements, Dekker, M. (Ed.). Chapman and Hall/CRC Press/Kluwer, New York, ISBN: 0-8547-5504-4 9, pp: 819.

[9.] Ruegg, R., U. Gloor, R.N. Goel, G. Ryser, O. Wiss and O. Isler, 1959. Synthese von ubichinon(45) and ubichinon (50). Helv. Chim. Acta, 52: 2616. DOI: 10.1002/hlca.19590420733

[10.] Inoue, S., R. Yamaguchi, K. Saito and K. Sato, 1974. The synthesis of coenzyme Q. Bull. Chem. Soc. Jap., 47: 3098. DOI: 10.1246/bcsj.47.3098

[11.] Naruta, Y. and K. Maruyama, 1979. Regio and stereocontrolled polyprenylation of quinines. A new synthetic method of coenzyme [Q.sub.2], [Q.sub.3] [Q.sub.9] and [Q.sub.10]. Chem. Lett., 885. DOI: 10.1246/cl.1979.885

[12.] Yoshizawa, T., H. Toyofuku, K. Tachibana and T. Kuroda, 1982. Regioselective polyprenyl rearrangement of polyprenyl 2, 3, 4, 5-tetrasubtituted phenyl ethers promoted by boron trifluoride. Chem. Lett., 11: 1131-1134. DOI: 10.1246/cl.1982.1131

[13.] Eto, H. and C. Eguchi, 1988. Novel solvent effect in the practical synthesis of Ubiquinone-10. Chem. Lett., 1597. DOI: 10.1246/cl.1988.1597

[14.] Van Liemt, W.B.S., W.F. Steggerda, R. Esmeijer and J. Lugtenburg, 1994. Synthesis and spectroscopic characterization of [sup.13]C-labelled ubiquinone-0 and ubiquinone-10. Recl. Trav. Chim. Pays-Bas., 113: 153-161. http://www.scopus.com/scopus/record/display.url?ei d=2-s2.0-0001946801&view=basic&origin=inward&txGid=T 371xC8G9sc8FxnM-Q-fBV1%3a2

[15.] Terao, S. K. Kato, M. Shiraishi and H. Morimoto, 1979. Synthesis of ubiquinones. 2. An efficient preparation of ubiquinone-10. J. Org. Chem., 44: 868. DOI: 10.1021/jo01319a051

[16.] Fujita, Y., M. Ishiguro, T. Onishi and T. Nishida, 1982. A new efficient and stereoselective synthesis of Ubiquinone-10. Bull. Chem. Soc. Jap., 55: 1325. DOI: 10.1246/bcsj.55.1325

[17.] Sato, K., O. Miyamoto, S. Inoue, T. Yamamto and Y. Hirasawa, 1982. An efficient stereoselective synthesis of co-enzyme [Q.sub.10]. J. Chem. Soc., Chem. Commun., 153. DOI: 10.1039/C39820000153

[18.] Masaki, Y., K. Hashimoto and K. Kaji, 1984. Synthetic studies on isoprenoidquinones. 1. A facile region and streo controlled synthesis of protected hydroquinones with an omega-hydroxyprenyl or omega-hydroxygeranyl side chain. Chem. Pharm. Bull., 32: 3959. http://www.journalarchive.jst.go.jp/english/jnlabstr act_en.php?cdjournal=cpb1958&cdvol=32&noissu e=10&startpage=3959

[19.] Masaki, Y., K. Hashimoto, K. Sakuma and K. Kaji, 1984. Synthetic studies on isoprenoidquinones. II. Syntheses of Ubiquinone-10, phylloquinone,and Menaquinone-4 by a chain-extending method utilizing terminally functionalized isoprenoidhydroquinones. Chem. Pharm. Bull., 32: 3952. http://www.journalarchive.jst.go.jp/english/jnlabstr act_en.php?cdjournal=cpb1958&cdvol=32&noissu e=10&startpage=3952

[20.] Mohri, M., H. Kinoshita, K. Inomata, H. Kotake, H. Takagaki and K. Yamazaki, 1986. Palladium-catalyzed region and streoselective reduction of allylic compounds with LiBE[t.sub.3]. Application to the synthesis of Co-enzyme [Q.sub.10]. Chem. Lett., 15: 1177-1180. DOI: 10.1246/cl.1986.1177

[21.] Lipshutz, B.H., P. Mollard, S.S. Pfeiffer and W. Chrisman, 2002. A short, highly efficient synthesis of coenzyme [Q.sub.10]. J. Am. Chem. Soc., 124: 14282-14283. DOI: 10.1021/ja021015v

[22.] Min, J.H., J.S. Lee, J.D. Yang and S. Koo, 2003. The friedel-Crafts allylation of a prenyl group stabilized by a sulfonemoiety: Expeditious syntheses of ubiquinones and menaquinones. J. Org. Chem., 68: 7925-7927. DOI: 10.1021/jo0350155

[23.] Eren, D. and E. Keinan, 1988. Total synthesis of linear polyprenoids. 3. Syntheses of ubiquinones via palladium-catalyzed oligomerization of monoterpene monomers. J. Am. Chem. Soc., 110: 4356-4362. DOI: 10.1021/ja00221a040

[24.] Keinan, E. and D. Eren, 1988. Total synthesis of polyprenoid natural products via pd(0)-catalyzed oligomerizations. Pure Applied Chem., 60: 89-98. http://media.iupac.org/publications/pac/1988/pdf/6 001x0089.pdf

[25.] Yanagisawa, A., N. Nomura, Y. Nortitake and H. Yamamoto, 1991. Highly [S.sub.N]2'-, (E)-, and antiselective alkylation of allylic phosphates. Facile synthesis of coenzyme [Q.sub.10]. Synthesis, 12: 1130-1036. http://cat.inist.fr/?aModele=afficheN&cpsidt=5179286

[26.] Negishi, E.I., S.Y. Liou, C.D. Xu and S.Q. Huo, 2002. A novel, highly selective and general methodology for the synthesis of 1,5-diene-containing oligoisoprenoids of all possible geometrical combinations exemplified by an lterative and convergent synthesis of Coenzyme [Q.sub.10]. Org. Lett., 4: 261-264. DOI: 10.1021/oL010263d

[27.] Folkers, K. and Y. Yamaura, 1984. Biomedical and clinical aspects of coenzyme Q. Proceedings of the International Symposium on Coenzyme Q, Oct. 24-26, Martinsried, Munich, West Germany, pp: 432. https://www.alibris.com/search/books/isbn/978044 4803801

Suryachandra Rao Ravada, Lakshma Reddy Emani, Machi Raju Garaga, Bharani Meka and Trimurtulu Golakoti

Laila Impex R and D Center, Unit-I, Phase-III, Jawahar Autonager, Vijayawada-520007, India

Corresponding Author: Trimurtulu Golakoti, Laila Impex R and D Center, Unit-I, Phase-III, Jawahar Autonager, Vijayawada-520007, India
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