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Recyclable Organomolybdenum Lewis Acid Catalyst and Microwave Assisted Pechmann Condensation Reactions

Recyclable Organomolybdenum Lewis Acid Catalyst and Microwave Assisted Pechmann Condensation Reactions. Student : Chia-Pei Chung Supervisor : Prof. Shuchun Joyce Yu 2006 / 07 / 20 Department of Chemistry & Biochemistry Chung Cheng University. Pechmann Condensation.

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Recyclable Organomolybdenum Lewis Acid Catalyst and Microwave Assisted Pechmann Condensation Reactions

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  1. Recyclable Organomolybdenum Lewis Acid Catalyst and Microwave Assisted Pechmann Condensation Reactions Student : Chia-Pei Chung Supervisor : Prof. Shuchun Joyce Yu 2006 / 07 / 20 Department of Chemistry & Biochemistry Chung Cheng University

  2. Pechmann Condensation • The Pechmann condensation is a synthesis of coumarins, starting from a phenol and a ester or carboxylic acid containing a β-carbonyl group. • Coumarin synthesis Woodruff, E. H. Organic Syntheses, 1944, 24, 69. Pechmann, H. V.; Duisberg, C. Ber.1883,16, 2119.

  3. Coumarins • present in seeds, root, and leaves of many plant species • As additives to food and cosmetics, optical brightening agents, and dispersed fluorescent and laser dyes • has clinical value as the precursor for several anticoagulants, antibacterial, anticancer • can be synthesized by one of such methods as the Claisen rearrangement, Perkin reaction, Knoevenagel condensation, Reformatsky reaction, Wittig reactions, as well as the Pechmann Condensation reaction

  4. Acidic Catalysts for Pechmann Condensation • Proton Donor Brønsted Acids H2SO4, HCl, TFA (trifluoroacetic acid) Pechmann V. H.; Duisberg C. Chem. Ber.1884, 17, 929. Woods, L. L.; Sapp, J. J. Org. Chem. 1962, 27, 3703. • Traditional Lewis Acid Catalysts InCl3, AlCl3, BiCl3, FeCl3, TiCl4, ZrCl4, P2O5, PCl3, POCl3 Bose, D. S.; Rudradas, A. P.; Babu, M. H. Tetrahedron Lett.2002, 43, 9195. S. K. De, R. A. Gibbs, Synthesis, 2005, 1231. Simmonis, H.; Remmert, P. Chem. Ber.1914, 47, 2229. Robertson, A.; Sandrock, W. F.; Henry, C. B. J. Chem. Soc.1931, 2426.

  5. Acidic Catalysts for Pechmann Condensation -- continued • Lanthanide Lewis Acid Catalysts Yb(III), Sm(III) Fillion, E. et. al. J. Org. Chem. 2006, 71, 409. Bahekar, S. S.; Shinde, D. B. Tetrahedron Lett. 2004, 45, 7999. • Others graphite / montmorillonite K10 Amberlyst-15, Nafion Heteropoly acid (H6P2W18O62．24H2O) Fre`re, S.; Thie´ry, V.; Besson, T. Tetrahedron Lett.2001, 42, 2791. Sabou, R.; Hoelderich, W. F.; Ramprasad, D.; Weinand, R. J. Catal.2005, 232, 34. Laufer, M. C.; Hausmann, H.; Hölderich, W. F. J. Catal.2003, 218, 315. Autino, J. C. et. al. Tetrahedron Lett.2004, 45, 8935.

  6. TFA Catalyzed Pechmann Condensation Phenol used: Phloroglucinol, 2-Methylresorcinol, Resorcinol, Orcinol, 4-Chlororesorcinol, Pyrogallol, 3-Hydroxydiphenyl amine β-carbonyl esters used: Ethyl benzoyl acetate Woods, L. L.; Sapp, J. J. Org. Chem. 1962, 27, 3703.

  7. Indium(III) Chloride Catalyzed Pechmann Condensation Phenol used: Resorcinol, Orcinol, 4-, Pyrogallol, 3-Hydroxydiphenyl amine, 3-methoxyphenol, 1,3,5-trihydroxybenzene, phenol, 1-naphthol Bose, D. S.; Rudradas, A. P.; Babu, M. H. Tetrahedron Lett.2002, 43, 9195.

  8. POCl3 Catalyzed Pechmann Condensation in Neutral Ionic Liquids Phenol used: Resorcinol, 2-Methylresorcinol, Orcinol, Pyrogallol, 1,3,5-trihydroxybenzene, 2',4'-Dihydroxyacetophenone Potdar, M. K.; Rasalkar, M. S.; Mohile, S. S.; Salunkhe, M. M. J. Mol. Catal. A Chem.2005, 235, 249.

  9. Yb(OTf)3 Catalyzed Pechmann Condensation Phenol used:3,5-dimethoxyphenol, 3,4-dimethoxyphenol, sesamol, 3-methoxy-2-methylphenol Fillion, E. et. al. J. Org. Chem. 2006, 71, 409.

  10. Microwave acceleration of the Pechmann reaction on graphite/montmorillonite K10 a. No modifications were observed when a preliminary activation (2 h at 180°C) of the clay was realized. b. No significant results were observed in the absence of graphite (montmorillonite K10 + phenol + b-ketoester). Fre`re, S.; Thie´ry, V.; Besson, T. Tetrahedron Lett.2001, 42, 2791.

  11. Wells–Dawson heteropolyacid Catalyzed Pechmann Condensation Phenol used: resorcinol, phloroglucinol, 3-methoxyphenol, pyrogallol, 3,4-dimethylphenol, 3-methylphenol, orcinol, 1-naphthol Romanelli,G. P.; Bennardi, D.; Ruiz, D. M.; Baronetti, G.; Thomas, H. J.; Autino, J. C. Tetrahedron Lett.2004, 45, 8935.

  12. Synthesis of Coumarins by Grubbs’ Catalyst Van, T. N.; Debenedetti, S.; Kimpe, N. D. Tetrahedron Lett.2003, 44, 4199.

  13. Disadvantages of Brønsted Acids • Proton Donor Brønsted Acids • Catalysts have to be used in excess, for example sulfuric acid, 10–12 equiv, trifluoroacetic acid, 3–4 equiv. • Longer reaction time and very often temperatures to be excess 150 oC and above. • Their corrosive nature and the formation of several side products make them difficult to handle. • The disposal of acidic waste leads to environmental pollution.

  14. Disadvantages of Traditional and Lanthanide Lewis Acid • Traditional Lewis Acid Catalysts • Many chlorinated derivatives are highly moisture sensitive and hydrolyse rapidly under conventional storage or standard reaction conditions. • The disposal of acidic waste leads to environmental pollution. • Can not control electronic and steric environments around metal Lewis acid center. • Lanthanide Lewis Acid Catalysts • Lanthanide metals are relatively rare.

  15. Motivation • Low Oxidation State Transition Metals • Relatively high moisture – and oxygen – stability • Inexpensive • Tunable electronic and steric environments around metal center • GreenChemistry • Greener solvents R.T. ionic liquids, [Bmim]PF6 • Energy saving Catalysis under microwave flash heating replace thermal heating • Recyclable catalyst

  16. Preparation of Organomolybdenum Catalyst • Thermal conditions

  17. Crotonaldehyde-Lewis Acid Adduct Childs, R. F. et. al. Can. J. Chem. 1982, 60, 801.

  18. Spectral Data of CO Coordinated Catalysts

  19. Organomolybdenum Lewis Acid Catalyzed Pechmann Condensation • Thermal conditions Solvent system: [bmim]PF6 or CH3CN or DMF or CH3NO2 or THF

  20. Ionic Liquids Seddon, K. R. et. al. Pure Appl. Chem.2000, 72, 2275.

  21. Coordinative Characteristics of Various Anions Wasserscheid, P., et. al.Angew. Chem. Int. Ed.2000,39, 3772.

  22. Room temperature ionic liquids exhibit many properties which make them potentially attractive media for homogeneous catalysis: • They have essentially no vapour pressure. • They generally have reasonable thermal stability. • They are able to dissolve a wide range of organic, inorganic and organometallic compounds. • The solubility of gases. • They are immiscible with some organic solvents. • Ionic liquids have been referred to as ‘designer solvents’ by a suitable choice of cation / anion.

  23. *After reacting 24 h, the products’ yield

  24. *After reacting 24 h, the products’ yield

  25. Thermal Heating Liquid boiling temperature is always lower than surface temperature of container Convection transition

  26. Mechanism of Microwave Heating Dipole Rotation

  27. Ionic Conduction

  28. Interactive Characteristic between Materials and Microwave Conductor (Metal Material) Reflective Insulator (Telflon) Transparent Dielectric Materials (Water) Absorptive

  29. Microwave Flash Heating Microwave energy Digestion bottle Liquid raises temperature quickly

  30. Preparation of Organomolybdenum Catalyst • Microwave Flash Heating Conditions

  31. Organomolybdenum Lewis Acid Catalyzed Pechmann Condensation • Microwave Flash Heating Conditions

  32. Microwave Flash Heating and Power Supply Curve

  33. Recyclability of Organomolybdenum Lewis Acid Catalyst Substrate Adduct Added Extraction CHCl3 Catalyst Solution Ionic Liquid [Bmim]PF6

  34. Recyclability of Organomolybdenum Lewis Acid Catalyst in [bmim]PF6

  35. Proposed Mechanism

  36. Proposed Mechanism

  37. Catalytic Reactivity of [A(2-py)3M(CO)(NO)2]2+ on Pechmann Condensation

  38. Catalytic Reactivity of [A(2-py)3M(CO)(NO)2]2+ on Mukaiyama Aldol Reaction 李婉甄碩士論文 ‘有機鉬金屬路易士酸在微波中對於Mukaiyama Aldol反應催化活性之探討’ 中正大學化學研究所, 2005.

  39. Catalytic Reactivity of [A(2-py)3M(CO)(NO)2]2+ on Diels Alder Reaction a:陳宜宏碩士論文 “水溶性有機鎢金屬路易士酸在綠色溶劑及微波中對於Diels-Alde 反應的影響”中正大學化學研究所, 2003. b:李婉甄碩士論文 ‘有機鉬金屬路易士酸在微波中對於Mukaiyama Aldol反應催化活性之探討’ 中正大學化學研究所, 2005. c: 傅耀賢博士論文 “過渡金屬錯合物觸媒的合成、催化活性以及動力學研究 中正大學化學研究所, 2001

  40. Conclusions • We have successfully demonstrated the catalytic activity of [O=P(2-py)3Mo(CO)(NO)2](BF4)2 for the synthesis of a variety of coumarins under solvent-free and ionic liquid system ([Bmim]PF6) conditions. This practical and simple method led to good yields of the coumarin derivatives under mild conditions and within short times. • The time economy, along with the conservation of the organomolybdenum Lewis acidcatalyst activity and the high recovery of the Lewis acid catalyst, play for both low environmental impact and low cost. Other green advantages of the procedure are the low formation of wastes, easy purification; and principally, the replacement of corrosive and environmental unfriendly acids.

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