068056ne

http://www.chemistrymag.org/cji/2004/068056ne.htm

Aug. 1, 2004 Vol.6 No.8 P.56 Copyright

Synthesis of novel chiral quaternary ammonium salt from rosin

Wang Hengshan, Tang Lidong, Pan Yingming, Liang Min
(School of Chemistry & Chemical Engineering, Guangxi Normal University, Guilin 541004)

Received Apr. 20, 2004; Supported by the National Natural Science Foundation of China (No. 20362002) and the Science Foundation for Youth of Guangxi province (No. 0229023).

Abstract Four novel chiral quaternary ammonium salts were synthesized from naturally occurring disproportionate rosin amine by isolation, methylation and alkylation. The products were synthesized with yield of 69%-93%. The target compounds were identified with FT-IR, NMR and MS.
Keywords chiral quaternary ammonium salt, rosin derivatives, synthesis

1 INTRODUCTION
The chrial quaternary ammonium salts have been widely used as chiral auxiliary in the field of asymmetric synthesis^[1-3] and enantiomer separation^[4]. And quaternary ammonium salts plays an important role in the surfactant industry as cationic surfactant, they have been widely used in many fields, such as cosmetic, fibre machining process, leather industry, sugar proficiency, medical treatment, sterilization and synthesis and so on^[5]_.
Rosin is a natural and easily available product, derivatives of which has been widely used as additives and modifiers for various applications in industries^[6]. For instance, rosin is effective as an adhesion promoter, viscosity controller, etc. All these useful properties are certainly related to the bulky alicyclic structure of rosin^[7]. Considering rosin holding several chrial carboatomic and stable structure, we designed and synthesized a series of novel chrial quaternary ammonium salts from rosin amine.
   The chiral quaternary ammonium salts 3a-3d were synthesized in 69%- 93% yields by alkylation of 2 which was prepared from available dehydroabietylamine 1. The reactions were shown in Scheme 1.

Scheme 1

2 EXPERIMENTAL
2.1 Materials and Instruments
Disproportionate rosin amine (Ginlin Chemical Factory); Formic acid, Formaldehyde solution (analytical pure, Guangzhou Chemical Factory); Benzyl bromide, Ethyl bromoacetate (chemical pure, Shanghai Chemical Reagent Co. Ltd); Benzyl chloride, Methyl iodide (analytical pure, Shanghai Chemical Reagent Co. Ltd); Other reagents and solvents were also obtained commercially. If necessary, solvents and reagents were dried and purified according to recommended procedures. The ¹H and ¹³C NMR spectra were recorded at 500 MHz on a Bruker ADVANCE AV spectrometers, respectively, with Me₄Si as the internal reference and CDCl₃ as the solvent. Infrared spectra were recorded on a Nicolet ESP 360 FT-IR spectrometer as KBr pellets. MS spectra were measured at 70 eV (EI) on a SHIMADZU QP5050A GC-MS spectrometers. Optical rotations () are quoted to ± 2% accuracy and were measured on a WZZ-2B monochromatic 589 nm (Optical activity) polarimeter at room temperature. Melting points (m.p.) were determined on a model X4 digital melting point apparatus, and the thermometer was uncorrected.
2.2 Isolation of dehydroabietylamine
To a solution of 142 g of disproportionate rosin amine dissolved in 237 ml of toluene was added a solution of 32.7 g (0.54 mol) of glacial acetic acid in 78 ml of toluene. The solution was stored at 10ºC for 2 hours. The crystalline salt was collected, washed with cold toluene, and recrystallized from 210 ml of boiling toluene. The color crystals were collected, washed several times with n-hexane, and air dried to obtain dehydroabietylamine acetate 68.7 g with m.p. 140-143ºC.
    A mixture of 54 g (0.16 mol) of dehydroabietylamine acetate was stirred with 200 ml water on the steam bath until the salt had dissolved. A total of 70 ml of 10% sodium hydroxide was added, the mixture was chilled, and the amine was extracted with 250 ml of ether. The ether solution was washed with water and dried over anhydrous potassium carbonate. After evaporation of the ether it gave a white viscous oil dehydroabietylamine 1 44 g (yield, 98%) which was crystallized after storage at room temperature for several days, m.p. 44-45ºC.
2.3 Synthesis of 2
To a 250ml three-neck flask was added dehydroabietylamine 1 (28.5 g, 0.1 mol), 85% formic acid (22 ml, 0.5 mol) was added under ice bath. The mixture was stirred at 50ºC until the solid was dissolved, followed by dropwise addition of 37% formaldehyde solution (17 ml, 0.23 mol) within 20 min, then heated at reflux for 12 hours under argon atmosphere. On completion (TLC), and the excessive formic acid and formaldehyde was removed under reduced pressure, the residue was resolved in 30 ml water. The reaction mixture was adjusted to pH=11 by 20% sodium hydroxide, and chilled, extracted with 250 ml of ether. The organic layer was washed with saturated sodium chloride solution and dried over anhydrous potassium carbonate. After evaporation of the ether a pale yellow viscous oil (+)-N,N-dimethyl-N- dehydroabietylamine 2 was obtained, 30.1 g (yield, 96%). ¹H NMR (500 MHz, CDCl₃, d , ppm): 1.23-1.25 (m, 9H), 1.34 (s, 3H), 1.45-1.48 (m, 4H), 1.80-1.84 (m, 2H), 1.88-1.93 (m, 1H), 2.34-2.38 (m, 2H), 2.82-2.84 (m, 1H), 2.85-2.87 (m, 2H), 2.96 (m, 6H), 3.01 (d, J=12.9 Hz, 1H), 3.24 (d, J=13.0 Hz, 1H), 6.89 (s, 1H), 7.02 (d, J=8.1 Hz, 1H), 7.17 (d, J=8.2 Hz, 1H).
2.4 Synthesis of 3a-3c
A solution of the (+)-N,N-dimethyl-N-dehydroabietylamine (5.00 mmol) and the necessary halide (5.10 mmol) were stirred in absolute ethanol under reflux until the amine had been consumed (4-12 hours). The reaction was monitored by TLC (methanol/trichloromethane 1:8). The solvent was removed under reduced pressure, and the residue was stirred with diethyl ether (30 ml) for 3h. The chiral quaternary ammonium salt was filtered off, and recrystallized from ethyl acetate/alcohol (20:1). The crystals were washed with diethyl ether or ethyl acetate, then dried in vacuo.
    3a White solid, yield 93%, m.p. 231-234ºC. = +12 (c=1.97, CHCl₃). IR (KBr, n , cm^-1): 3054,1606,1495 (Ph), 1062 (C-N). ¹H NMR (500 MHz, CDCl₃, d , ppm): 1.23-1.27 (m, 9H), 1.38-1.45 (m, 5H), 1.62 (m, 2H), 1.89-1.91 (m, 2H), 1.98-2.04(m, 2H), 2.33 (d, J=13.0 Hz, 1H), 2.83-2.89 (m, 2H), 2.97-3.05 (m, 1H), 3.30 (d, J=14.0 Hz, 1H), 3.37-3.45 (m, 6H), 4.08 (d, J=13.8 Hz, 1H), 5.16 (d, J=12.4 Hz, 1H), 5.24 (d, J=12.4Hz, 1H), 6.91 (s, 1H), 7.01 (d, J=7.2 Hz, 1H), 7.12 (d, J=8.1 Hz, 1H), 7.45-7.48 (m, 3H), 7.71 (d, J=6.3 Hz, 2H). ¹³C NMR (500 MHz, CDCl₃, d , ppm): 18.39, 19.77, 19.95, 23.94, 23.99, 25.46, 29.69, 33.45, 37.50, 37.99, 39.41, 40.47, 48.29, 75.85, 123.57, 124.02, 126.91, 129.09, 129.09, 130.67, 133.68, 133.68, 146.67. m/z (FAB) 43 (5.41%), 58 (100%), 91 (25.08%), 313 (0.09%), 404 (M⁺-Cl, 0.01%). Found [M-Cl]⁺ 404, C₂₉H₄₂N requires 404.
    3b White solid, yield 89%, m.p. 225-231ºC. = +11 (c=1.07, CHCl₃). IR (KBr, n , cm^-1): 3055,1603,1494 (Ph), 1062 (C-N). ¹H NMR (500 MHz, CDCl₃, d , ppm): 1.23-1.26 (m, 9H), 1.36-1.40 (m, 5H), 1.61-1.62 (m, 2H), 1.90-1.93 (m, 2H), 1.99-2.03 (m, 2H), 2.31 (d, J=13.0 Hz, 1H), 2.82-2.87 (m, 2H), 2.95-2.97 (m, 1H), 3.33 (d, J=14.2 Hz, 1H), 3.34 -3.45 (m, 6H), 4.11 (d, J=13.8 Hz, 1H), 5.21 (d, J=12.4 Hz, 1H), 5.31 (d, J=12.5 Hz, 1H), 6.90 (s, 1H), 7.01 (d, J=8.2 Hz, 1H), 7.11 (d, J=8.1 Hz, 1H), 7.42-7.46 (m, 3H), 7.72 (d, J=6.7 Hz, 2H). ¹³C NMR (500 MHz, CDCl₃, d , ppm): 18.39, 19.86, 20.01, 23.91, 23.97, 25.46, 29.67, 30.89, 33.45, 37.50, 38.02, 39.53, 40.60, 48.33, 51.43, 51.55, 72.09, 76.02, 123.54, 124.03, 126.95, 127.45, 129.15, 129.15, 130.79, 133.65, 133.65, 146.12, 146.61. m/z (FAB) 43 (13.72%), 58 (100%), 91 (73.23%), 313 (0.4%), 404 (M⁺-Br, 0.02%). Found [M-Br]⁺ 404, C₂₉H₄₂N requires 404.
    3c White solid, yield 69%, m.p. 214-216ºC. =+28 (c=1.10, CHCl₃). IR (KBr, n , cm^-1): 3032, 1612, 1465 (Ph), 1754 (C=O), 1196 (C-O), 1036 (C-N). ¹H NMR (500 MHz, CDCl₃, d , ppm): 1.21-1.99 (m, 23H), 2.34 (d, J=12.9 Hz, 1H), 2.83 (m, 1H), 2.98 (m, 2H), 3.66 (d, J=13.8 Hz, 1H), 3.76-3.77 (m, 6H), 4.03-4.05 (m, 2H), 4.06 (d, J=13.8 Hz, 1H), 5.08-5.15 (m, 2H), 6.90 (s, 1H), 7.00 (d, J=8.2 Hz, 1H), 7.12 (d, J=8.2 Hz, 1H). ¹³C NMR (500 MHz, CDCl₃, d , ppm): 13.95, 18.33, 19.86, 19.93, 23.90, 23.96, 25.41, 29.55, 32.50, 33.45, 37.48, 37.98, 38.98, 40.53, 47.94, 54.29, 62.73, 64.46, 75.47, 123.55, 124.01, 126.90, 134.08, 146.13, 146.60, 165.09. m/z (FAB) 43 (14.17%), 58 (100%), 102 (12.4%), 116 (19.94%), 130 (85.89%), 312 (0.62%), 400 (M⁺-Br, 0.01%). Found [M-Br]⁺ 400, C₂₆H₄₂N requires 400.
2.5 Synthesis of 3d
A solution of (+)-N,N-dimethyl-N-dehydroabietylamine (1.57 g, 5.00 mmol) and methyl iodide (0.71 g, 5.00 mmol) in toluene (10 ml) were stirred for 8 hours under argon atmosphere at room temperature. The resulting precipitate was collected by filtration and washed with ethyl acetate (2×20 ml) to give the product 3d as a white solid, yield 73%, m.p. 249-252ºC. =+22 (c=1.20, CHCl₃). IR (KBr, n , cm^-1): 3048,1610,1482 (Ph), 1062 (C-N). ¹H NMR (500 MHz, CDCl₃, d , ppm): 1.22-1.28 (m, 9H), 1.37 (s, 3H), 1.42-1.44 (m, 2H), 1.65-1.76 (m, 4H), 2.05 (m, 2H), 2.33 (d, J=12.8 Hz, 1H), 2.82-2.84 (m, 1H), 2.97-2.99 (m, 2H), 3.38 (d, J=14.0 Hz, 1H), 3.60 (s, 9H), 3.98 (d, J=13.9 Hz, 1H), 6.92 (s, 1H), 7.01 (d, J=8.0 Hz, 1H), 7.13 (d, J=8.2 Hz, 1H). ¹³C NMR (500 MHz, CDCl₃, d , ppm): 18.37, 19.82, 19.85, 23.94, 23.98, 25.55, 27.10, 29.61, 32.52, 33.44, 37.51, 38.01, 39.07, 40.70, 47.86, 56.79, 78.50, 123.55, 124.01, 126.94, 134.12, 146.07, 146.57. m/z (FAB) 43 (15.15%), 58 (100%), 127 (10.7), 142 (23.31%), 313 (0.43%), 328 (M⁺-I, 0.01%). Found [M-I]⁺ 328, C₂₃H₃₈N requires 328.

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