Biomimetic Oxidation of Veratryl Alcohol with H₂O₂ Catalyzed by Iron(III) Porphyrins and Horseradish Peroxidase in Ionic Liquid [1]

Abstract

3,4-Dimethoxybenzyl alcohol (veratryl alcohol) is a model compound for lignin substructures and its oxidation with H₂O₂ catalyzed by iron(III) porphyrins and horseradish peroxidase (HRP) in ionic liquids has been described. Veratraldehyde and 2-hydroxymethyl-5-methoxy-2,5-cyclohexadiene-1,4-dione were the two major products of the oxidation of veratryl alcohol at room ­temperature. The iron(III) porphyrin or HRP immobilized in ionic liquids showed increased catalytic activity and can be recycled and this is believed due to the stabilization of highvalent oxo­iron(IV) π-cation radical intermediate generated in the reaction.

ionic liquid - veratryl alcohol - oxidation - iron(III) porphyrins - horseradish peroxidase (HRP)

References and Notes

1

Part of the work was presented at: Modern Trends in Inorganic Chemistry-X (MTIC-X), Bombay, India, December, 2003.

2 Chattopadhyay K. Mozumdar S. Biochemistry  2000,  39:  263 

3 Chauhan SMS. Mohapatra PP. Kalra B. Kohli TS. Satapathy S. J. Mol. Catal. A: Chem  1996,  113:  239 

4 Chauhan SMS. Sahoo BB. Bioorg. Med. Chem.  1999,  7:  2629 

5a Labat G. Seris JL. Meunier B. Angew. Chem., Int. Ed. Engl.  1990,  29:  1488 

5b Robert A. Meunier B. New J. Chem.  1988,  12:  885 

5c Higuchi T. Satake C. Hirobe M. J. Am. Chem. Soc.  1995,  117:  8879 

6 Wood, J. M.; Folsom, B. R.; Eudy, E. W. In Proceedings of the 3rd International Conference on Biotechnology in the Pulp and Paper Industry, Stockholm, June 16-19, 1986

7 Turk H. Ford WT. J. Org. Chem.  1991,  56:  1253 

8a Labat G. Meunier B. C. R. Acad. Sci. Paris  1990,  311:  625 

8b Crestini C. Saladino R. Tagliatesta P. Boschi T. Bioorg. Med. Chem.  1999,  7:  1897 

9 Klibanov AM. Nature (London)  2001,  409:  241 

10 Klibanov AM. Trends Biotechnol.  1997,  15:  97 

11a Jain N. Kumar A. Chauhan S. Chauhan SMS. Tetrahedron  2005,  61:  1015 

11b Dupont J. de Souza RF. Suarez PAZ. Chem. Rev.  2002,  102:  3667 

12 Kragl U. Eckstein M. Kaftzik N. Curr. Opin. Biotechnol.  2002,  13:  565 

13 Van Rantwijk F. Lau RM. Sheddon RA. Trends Biotechnol.  2003,  21:  131 

14 Okrasa K. Guibe-Jampel E. Therisod M. Tetrahedron: Asymmetry  2003,  14:  2487 

15 Compton DL. Laszlo JL. Joseph A. J. Electroanal. Chem.  2002,  520:  71 

16 Srinivas KA. Kumar A. Chuahan SMS. Chem. Commun.  2002,  2456 

17 Chauhan SMS. Kumar A. Srinivas KA. Chem. Commun.  2003,  2348 

18 Jain N. Kumar A. Chauhan SMS. Tetrahedron Lett.  2005,  46:  2599 

19 Gelpke MDS. Lee J. Gold MH. Biochemistry  2002,  41:  3498 

20 Costanzo LD. Geremia S. Randaccio L. Purrello R. Lauceri R. Sciotto D. Gulino FG. Pavone V. Angew. Chem. Int. Ed.  2001,  40:  4245 

21 Li Z. Xia C.-G. Tetrahedron Lett.  2003,  44:  2069 

22

Representative Procedure for Oxidation of Veratryl Alcohol ( 1) with H ₂ O ₂ Catalyzed by Iron(III) Porphyrins in Ionic Liquid: H₂O₂ (30%; 113 µL, 100 mmol) was added with stirring at r.t to a solution of water-soluble iron(III) porphyrin (1 mmol, 10%) and veratryl alcohol (100 mmol) in the ionic liquid [bmim][PF₆] (2.0 mL). The 20-µL aliquots were taken at 30 min interval and analyzed by HPLC analysis at 280 nm. After completion of the reaction the reaction mixture was extracted with Et₂O and the ionic liquid containing iron(III) porphyrin was recovered. The Et₂O layer was dried over anhyd Na₂SO₄ and evaporated under reduced pressure. The residue was column chromatographed over silica gel and the products were identified by ¹H NMR, IR and MS spectral data.
Representative Procedure for Oxidation of Veratryl Alcohol ( 1) with H ₂ O ₂ Catalyzed by HRP in Ionic Liquid: Veratryl alcohol (100 mmol) was dissolved in the ionic liquid [bmim][PF₆] (2.0 mL) in a 5-mL round-bottomed flask fitted with a magnetic stirrer. HRP [100 µL, 1.0 mg dissolved in 1 mL buffer (pH 4.5)] was added to the reaction mixture and H₂O₂ (30%; 113 µL, 100 mmol) was added to the reaction mixture with stirring. The stirring was continued at r.t. and 20-µL aliquots were taken at 30 min interval and analyzed by HPLC at 280 nm. After completion of the reaction the reaction mixture was extracted with Et₂O and the ionic liquid containing HRP was recovered. The Et₂O layer was dried over anhyd Na₂SO₄ and evaporated under reduced pressure. The residue was column chromatographed over silica gel and the products were identified by ¹H NMR, IR and MS spectra.

23

Spectroscopic Data3,4-Dimethoxybenzaldehyde (Veratraldehyde; 2): IR (KBr): 2987, 2934, 1729, 1623, 1511, 1256, 1167, 1046, 986, 913, 789, 725 cm^-1. ¹H NMR (CDCl₃): δ = 3.89 (s, 6 H), 6.86 (s, 1 H), 6.98 (d, J = 7.35 Hz, 1 H), 7.03 (d, J = 7.35 Hz, 1 H), 10.67 (s, 1 H). MS (ESI): m/z = 166 [M⁺], 151, 138, 136, 123, 94, 73.
2-Hydroxymethyl-5-methoxy-2,5-cyclohexadiene-1,4-dione ( 3): IR (KBr): 3310, 2948, 1665, 1644, 1619, 1607, 1226, 1144 cm^-1. ¹H NMR (CDCl₃): δ = 3.85 (s, 3 H), 3.92 (s, 1 H), 4.52 (d, J = 2.3 Hz, 2 H), 6.10 (s, 1 H), 6.78 (t, J = 2.3 Hz, 1 H). MS (ESI): m/z = 168 [M⁺], 153, 150, 44.