Preparation of Soluble Polymeric Supports with a Functional Group for Liquid-Phase Organic Synthesis

Abstract

Soluble copolymers of styrene with functional groups were prepared by radical co-polymerization of styrene with various substituted styrenes. They were characterized by NMR spectroscopy and their molecular weight was determined by size exclusion chromatography.

Key words

polymerization - soluble copolymer - polystyrene - functional group

References

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15

4-Vinylbenzyl Azide 2: A mixture of 2 g (13 mmol) of 4-vinylbenzylchloride, 1.7 g (26 mmol) of sodium azide and 0.2 g (1.3 mmol) of sodium iodide in 25 mL of DMSO was stirred at 80 °C for 15 h, cooled, and treated with 25 mL of water and 75 mL of ether. The organic phase was separated, washed with water and then dried with magnesium sulfate. Yield 90%. ¹H NMR (CDCl₃): δ 7.41 (d, 2 H, J = 8.1, Ar-H); 7.25 (d, 2 H, J = 8.1, Ar-H); 6.71 (dd, 1 H, J = 10.7, 17.8, CH=C); 5.75 (d, 1 H, J = 17.8, C=CH₂); 5.25 (d, 1 H, J = 10.7, C=CH₂); 4.29 (s, 2 H, CH₂N₃). ¹³C NMR (CDCl₃): δ 138.3, 136.9, 135.4, 129.1, 127.3, 115.1, 55.2.

17

Sulfonamide 3: Allylamine (1.1 mL, 14.2 mmol) was added to a solution of p-styrene-sulfonylchloride (1.44 g, 7.11 mmol) in a solution of dichloromethane-triethylamine (13 mL, 10:3). The mixture was stirred for 15 h at room temperature, and then acidified by a 0.25 N aqueous HCl solution (10 mL). The organic products were extracted with ethyl acetate (3 × 20 mL). The combined organic layers were washed with brine and dried with magnesium sulfate. After evaporation of the solvent, the residue was purified by chromatography on silica gel (CH₂Cl₂). The monomer was isolated as a colorless oil (1.25 g, Yield 79%). ¹H NMR (CDCl₃): δ 7.83 (d, 2 H, J = 8.4, Ar-H); 7.52 (d, 2 H, J = 8.4, Ar-H); 6.75 (dd, 1 H, J = 10.9, 17.5, (Ar)-CH=C); 5.88 (d, 1 H, J = 17.5, (Ar)-C=CH₂); 5.72 (m, 1 H, J = 17.3, 10.2, 5.6, CH=CH₂); 5.42 (d, 1 H, J = 10.9, (Ar)-CH=CH₂); 5.16 (d, 1 H, J = 17.3, CH=CH₂); 5.07 (d, 1 H, J = 10.2, CH=CH₂); 4.83 (s, 1 H, NH); 3.60 (m, 2 H, CH₂). ¹³C NMR (CDCl₃): δ 142.4, 139.3, 135.9, 133.5, 128.1, 127.4, 118.3, 118.0, 46.3.

18

Sulfonamide 4: A 80% w/w solution of propargyl bromide (97 mg, 0.65 mmol) in toluene was added to a mixture of allyl p-styrenesulfonamide (120 mg, 0.48 mmol) and cesium carbonate (213 mg, 0.65 mmol) in DMF (1.2 mL). The mixture was stirred for 15 h at room temperature, then 9 mL of ethyl acetate was added. The mixture was washed with a saturated ammonium chloride aqueous solution and the organic products were extracted with ethyl acetate (3 × 10 mL). The combined organic layers were washed with brine and then dried with magnesium sulfate. After evaporation of the solvent, the residue was purified by chromatography on silica gel (CH₂Cl₂). The monomer 4 was obtained as a colorless oil (123 mg, Yield 92%). ¹H NMR (CDCl₃): δ 7.84 (d, 2 H, J = 8.3, Ar-H); 7.53 (d, 2 H, J = 8.3, Ar-H); 6.76 (dd, 1 H, J = 10.9, 17.6, (Ar)-CH=CH₂); 5.88 (d, 1 H, J = 17.6, (Ar)-CH=CH₂); 5.74 (ddt, 1 H, J = 17.3, 10.2, 5.6, CH=CH₂); 5.44 (d, 1 H, J = 10.9, (Ar)-CH=CH₂); 5.29 (d, 1 H, J = 17.3, CH=CH₂); 5.07 (d, 1 H, J = 10.2, CH=CH₂); 4.05 (d, 2 H, J = 2.6, CH₂-CCH); 3.60 (d, 2 H, J = 5.6, CH₂); 1.63 (t, 1 H, J = 2.6, CCH).

19

General Procedure for the Preparation of Copolymers 5-13: AIBN (11.6 mg, 0.07 mmol) was added to a solution of styrene (1.43 g, 13.8 mmol) and monomer (0.42 mmol) in toluene (5.3 mL), and the mixture was stirred for 40 h at 70 °C under inert atmosphere. After evaporation of the solvent, dichloromethane (4.5 mL) was added to the residue and the solution was dropped into methanol (23 mL) with strong stirring, at room temperature, to precipitate the polymer. The resulting suspension was filtered, washed with methanol and dried under vacuum.
Copolymers 5-13. Selected data. For all the copolymers 5-13: ¹H NMR (CDCl₃): δ 7.3-6.2 (brd signal, Ar-H PS); 2.2-1.2 (brd signal, -CH-CH₂- PS). ¹³C NMR (CDCl₃): δ 147.0-145.0, 129.1-126.0, 47.0-40.5. 5: ¹H NMR (CDCl₃): δ 4.60 (s, 2 H, CH₂O). ¹³C NMR (CDCl₃): δ 66.0 (CH₂OH). 6: ¹H NMR (CDCl₃): δ 4.21 (s, 2 H, CH₂N₃). ¹³C NMR (CDCl₃): δ 133.1, 55.2. 7: ¹H NMR (CDCl₃): δ 3.74 (s, 2 H, CH₂NH₂). 8: ¹H NMR (CDCl₃): δ 4.97 (s, 2 H, CH₂O); 4.61 (s, 2 H, CH₂OH). ¹³C NMR (CDCl₃): δ 159.2, 134.6, 133.9, 129.7, 115.5, 70.6, 65.6. 9:¹H NMR (CDCl₃): δ 5.89 (brd s, 1 H, CH=CH₂); 5.02 (brd s, 2 H, CH=CH₂); 2.65 (s, 2 H, Ph-CH₂), 2.35 (brd s, 2 H, CH₂-CH=CH₂). ¹³C NMR (CDCl₃): δ 139.0, 115.4, 36.3, 35.7. 11: ¹H NMR (CDCl₃): δ 7.52 (brd s, 2 H, Ar-H); 4.65 (brd s, 1 H, CH); 2.2-1.2 (CH₃). 12: ¹H NMR (CDCl₃): δ 7.54 (brd s, 2 H, Ar-H); 5.71 (brd s, 1 H, CH=CH₂); 5.14 (m, 2 H, CH=CH₂); 3.52 (brd s, 2 H, CH₂-CH=C). 13: ¹H NMR (CDCl₃): δ 7.46 (brd s, 2 H, Ar-H); 5.72 (brd s, 1 H, CH=CH₂); 5.28 (m, 2 H, CH=CH₂); 4.03 (brd s, 2 H, CH₂-CCH); 3.78 (brd s, 2 H, CH₂-CH=CH₂); 2.2-1.2 (-C≡CH). ¹³C NMR (CDCl₃): δ 136.4, 132.5, 120.7, 78.7, 74.4, 49.6, 36.4.