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DOI: 10.1055/s-2004-815436
DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) - A Nucleophillic Base
Publication History
Publication Date:
26 January 2004 (online)
Biographical Sketches
The efficiency of DBU as a non-nucleophilic, sterically hindered, tertiary amine base in organic chemistry has been widely demonstrated. [1] In particular, it has been widely used for carrying out dehydrohalogenation reactions. However, Reed et al. demonstrated for the first time the remarkably strong nucleophilic behavior of DBU in its reaction with halogenated compounds. [2] This nuclephilic behavior of DBU, thus unveiled, also explained many of its so-called unexpected and unusual reactions. [3-5] Subsequently, many other workers have also reported the nucleophilic behaviour of DBU. [6] In many instances, DBU itself reacted with different a,b-unsaturated systems resulting in the formation of e-caprolactam derivative. [7] The reagent is commercially available and has been extensively used for carrying out a wide range of reactions. [8]
Abstracts
(A) The Baylis-Hillman reaction is of great synthetic utility, as it converts simple starting materials into densely functionalized products. Recently, Agarwal et al. showed the superiority of DBU over other amine catalysts in the Baylis-Hillman reaction, as it was stable under the reaction conditions and gave a clean reaction with the fastest rate. [9] |
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(B) The conversion of primary or secondary nitroalkanes into aldehydes or ketones, i.e. Nef reaction originally involved strong acidic conditions. Ballini et al. showed an unprecedented behavior of DBU as a new reagent in acetonitrile solution for the one-step regio- and chemoselective conversion of secondary nitro compounds in the presence of primary nitro compounds into ketones under homogeneous basic conditions in good yields. [10] |
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(C) Mizuno et al. developed a new chemical fixation of carbon dioxide in the presence of DBU to form substituted 1H-quinazoline-2,4-diones, which are useful for the synthesis of different medicinal intermediates. In this reaction, CO2 smoothly reacts with 2-aminobenzonitrile under mild conditions, assisted either by an excess of DBU (1 atm, 20 °C) or catalytic amount of DBU (10 atm, 80 °C) to give the corresponding quinazoline derivatives. [11] The authors also synthesized substituted 2,4-dihydroxyquinazolines by chemical fixation of CO2 (1 atm) of 2-aminobenzonitrile at 20 °C in presence of DBU. [12] |
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(D) Recently, Shieh et al. showed the efficiency of DBU as a nucleophilic catalyst in the environmentally friendly method for the methylation [13] and benzylation [14] of N-, O- and S-atoms with nontoxic dimethylcarbonate (DMC) and dibenzylcarbonate (DBC), respectively. These authors also showed the superiority of DBU over the commonly used acylation catalyst 4-(dimethylamino)pyridine in the esterification of benzoic acid with DMC. [15] |
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(E) DBU was also found to smoothly cleave the N-acetyl and N-benzoyl derivatives of carbazoles, indoles, and nitroanilines in refluxing methanol, and the parent amines were recovered in excellent yields. The cleavage was also accomplished in acetonitrile solution under reflux and under microwave irradiation. [6d] |
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(F) Recently, in the synthesis of duocarmycin and CC-1065 analogues, the parent members of an important class of potent antitumor antibiotics, Boger and his co-workers used DBU in anhydrous acetonitrile solution to bring about spirocyclization to create a cyclopropane ring in the final step of the synthesis in good yield. [16] |
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-
1a
Oediger H.Möller F.Eiter K. Synthesis 1972, 591 -
1b
Hermecz I. Advances in Heterocyclic ChemistryKatritzky AR. Academic Press Inc.; New York: 1987. Chap. 42. p.83 - 2
Reed R.Reau R.Dahan F.Bertrand G. Angew. Chem., Int. Ed. Engl. 1993, 32: 399 - 3
Juneja IR.Garg DK.Schafer W. Tetrahedron 1982, 38: 551 - 4
McCoy LL.Mal D. J. Org. Chem. 1981, 46: 1016 - 5
House HO.de Tar MB.van der Veer D. J. Org. Chem. 1979, 44: 3793 -
6a
Sutherland JK. Chem Commun. 1997, 325 -
6b
Perbost M.Lucas M.Chavis C.Imbach J.-L.
J. Heterocycl. Chem. 1993, 30: 627 -
6c
Chambers RD.Roche AJ.Batsanov AS.Howard JAK. J. Chem. Soc., Chem Commun. 1994, 2055 -
6d
Chakrabarty M.Ghosh N.Khasnobis S.Chakrabarty M. Synth. Commun. 2002, 32: 265 -
7a
Lammers H.Cohen-Fernandes P.Habraken CL. Tetrahedron 1994, 50: 865 -
7b
Chakrabarty M.Batabyal A.Patra A. J. Chem. Res., Synop. 1996, 190 -
7c
Page PCB.Vahedi H.Bethell D.Barkley JV. Synth. Commun. 2003, 33: 1937 -
7d
Im YJ.Gong JH.Kim HJ.Kim JN. Bull. Korean Chem. Soc. 2001, 22: 1053 -
8a
Barton DHR.Zard SZ. J. Chem. Soc., Chem. Commun. 1985, 1098 -
8b
Barton DHR.Kervagoret J.Zard SZ. Tetrahedron 1990, 46: 7587 -
8c
Pelkey ET.Chang L.Gribble GW. Chem. Commun. 1996, 1909 -
8d
Pelkey ET.Gribble GW. Synthesis 1999, 1117 -
8e
Suzuki M.Yoneda N. J. Org. Chem. 1976, 41: 1482 - 9
Aggarwal VK.Mereu A. Chem. Commun. 1999, 2311 - 10
Ballini R.Bosica G.Fiorini D.Petrini M. Tetrahedron Lett. 2002, 43: 5233 - 11
Mizuno T.Ishino Y. Tetrahedron 2002, 58: 3155 - 12
Mizuno T.Okamoto N.Ito T.Miyata T. Tetrahedron Lett. 2000, 41: 1051 - 13
Shieh W.-C.Dell S.Repic O. Org. Lett. 2001, 3: 4279 - 14
Shieh W.-C.Lozanov M.Loo M.Repic O.Blacklock TJ. Tetrahedron Lett. 2003, 44: 4563 - 15
Shieh W.-C.Dell S.Repic O. J. Org. Chem. 2002, 67: 2188 - 16
Parrish JP.Kastrinsky DB.Hwang I.Boger DL. J. Org. Chem. 2003, 68: 8984
References
-
1a
Oediger H.Möller F.Eiter K. Synthesis 1972, 591 -
1b
Hermecz I. Advances in Heterocyclic ChemistryKatritzky AR. Academic Press Inc.; New York: 1987. Chap. 42. p.83 - 2
Reed R.Reau R.Dahan F.Bertrand G. Angew. Chem., Int. Ed. Engl. 1993, 32: 399 - 3
Juneja IR.Garg DK.Schafer W. Tetrahedron 1982, 38: 551 - 4
McCoy LL.Mal D. J. Org. Chem. 1981, 46: 1016 - 5
House HO.de Tar MB.van der Veer D. J. Org. Chem. 1979, 44: 3793 -
6a
Sutherland JK. Chem Commun. 1997, 325 -
6b
Perbost M.Lucas M.Chavis C.Imbach J.-L.
J. Heterocycl. Chem. 1993, 30: 627 -
6c
Chambers RD.Roche AJ.Batsanov AS.Howard JAK. J. Chem. Soc., Chem Commun. 1994, 2055 -
6d
Chakrabarty M.Ghosh N.Khasnobis S.Chakrabarty M. Synth. Commun. 2002, 32: 265 -
7a
Lammers H.Cohen-Fernandes P.Habraken CL. Tetrahedron 1994, 50: 865 -
7b
Chakrabarty M.Batabyal A.Patra A. J. Chem. Res., Synop. 1996, 190 -
7c
Page PCB.Vahedi H.Bethell D.Barkley JV. Synth. Commun. 2003, 33: 1937 -
7d
Im YJ.Gong JH.Kim HJ.Kim JN. Bull. Korean Chem. Soc. 2001, 22: 1053 -
8a
Barton DHR.Zard SZ. J. Chem. Soc., Chem. Commun. 1985, 1098 -
8b
Barton DHR.Kervagoret J.Zard SZ. Tetrahedron 1990, 46: 7587 -
8c
Pelkey ET.Chang L.Gribble GW. Chem. Commun. 1996, 1909 -
8d
Pelkey ET.Gribble GW. Synthesis 1999, 1117 -
8e
Suzuki M.Yoneda N. J. Org. Chem. 1976, 41: 1482 - 9
Aggarwal VK.Mereu A. Chem. Commun. 1999, 2311 - 10
Ballini R.Bosica G.Fiorini D.Petrini M. Tetrahedron Lett. 2002, 43: 5233 - 11
Mizuno T.Ishino Y. Tetrahedron 2002, 58: 3155 - 12
Mizuno T.Okamoto N.Ito T.Miyata T. Tetrahedron Lett. 2000, 41: 1051 - 13
Shieh W.-C.Dell S.Repic O. Org. Lett. 2001, 3: 4279 - 14
Shieh W.-C.Lozanov M.Loo M.Repic O.Blacklock TJ. Tetrahedron Lett. 2003, 44: 4563 - 15
Shieh W.-C.Dell S.Repic O. J. Org. Chem. 2002, 67: 2188 - 16
Parrish JP.Kastrinsky DB.Hwang I.Boger DL. J. Org. Chem. 2003, 68: 8984