An Efficient Synthesis of Pyrazolo[3,4-b]pyridine Derivatives in Ionic Liquid

REFERENCES

• Hardy , C. R. The chemistry of pyrazolopyridines . Adv. Heterocyclic Chem. 1984 , 36 , 343 – 409 .
   Web of Science ®Google Scholar
• Orth , R. E. Biologically active pyrazoles . J. Pharm. Sci. 1968 , 57 , 537 – 556 .
   PubMed Web of Science ®Google Scholar
• Elnagdi , M. H. ; Elmoghayar , M. R. H. ; Elgemeie , G. E. H. Chemistry of pyrazolopyrimidines. Adv. Hetreocyclic Chem. 1987, 41, 319–376.
   Web of Science ®Google Scholar
• Elnagdi , M. H. ; Elmoghayar , M. R. H. ; Sadek , K. U. Chemistry of pyrazoles condensed to heteroaromatic five- and six-membered rings . Adv. Hetreocyclic Chem. 1990 , 48 , 223 – 299 .
   Google Scholar
• Chen , Y. L. Pyrazolo- and pyrazolopyridines useful as CRF antagonists, International Patent WO 9534563 A1, 1995 ; Chem. Abstr. 1995 , 124 , 232447 .
   Google Scholar
• Quiroga , J. ; Alvarado , M. ; Insuasty , B. ; Moreno , R. 5-Cyanopyrazolo[3,4-b]pyridines in the reaction of 5-amino-3-methyl-1-phenylpyrazolo with arylidene derivatives of malonodinitrile and ethyl cyanoacetate . J. Heterocyclic Chem. 1999 , 36 , 1311 – 1316 .
   Web of Science ®Google Scholar
• Quiroga , J. ; Cruz , S. ; Insuasty , B. ; Abonia , R. Synthesis and structural analysis of 5-cyanodihydropyrazolo[3,4-b]pyridines . J. Heterocyclic Chem. 2001 , 38 , 53 – 60 .
   Web of Science ®Google Scholar
• (a) Dzyuba , S. V. ; Bartsch , R. A. Recent advances in applications of room-temperature ionic liquid/supercritical CO2 systems . Angew. Chem. Int. Ed. 2003 , 42 , 148 – 150 ; (b) Wilker , J. S. A short history of ionic liquids-form molten salts to neoteric . Green Chem. 2002 , 4 , 73 – 80 .
   PubMed Web of Science ®Google Scholar
• (a) Welton , T. Room-temperature ionic liquids. Solvents for synthesis and catalysis . Chem. Rev. 1999 , 99 , 2071 – 2084 ; (b) Dupont , J. ; de Souza , R. F. ; Suarez , P. A. Z. Ionic liquid (molten salt) phase organometallic catalysis . Chem. Rev. 2002 , 102 , 3667 – 3692 .
   PubMed Web of Science ®Google Scholar
• Earle , M. J. ; Seddon , K. R. ; Adams , C. J. ; Roberts , G. Friedel-Crafts reactions in room temperature ionic liquids . Chem. Commun. 1998 , 2097 – 2098 .
   Web of Science ®Google Scholar
• (a) Fischer , T. ; Sethi , A. ; Welton , T. ; Woolf , J. Diels-Alder reactions in room-temperature ionic liquids . Tetrahedron Lett. 1999 , 40 , 793 – 796 ; (b) Lee , C. W. Diels-Alder reactions in chloroaluminate ionic liquids: acceleration and selectivity enhancement . Tetrahedron Lett. 1999 , 40 , 2461 – 2464 ; (c) Ludley , P. ; Karodia , N. Phosphonium tosylates as solvents for the Diels-Alder reaction . Tetrahedron Lett. 2001 , 42 , 2011 – 2014 .
   Web of Science ®Google Scholar
• (a) Carmichael , A. J. ; Earle , M. J. ; Holbrey , J. D. ; McCormac , P. B. ; Seddon , K. R. The Heck reaction in ionic liquids: A multiphasic catalyst system . Org. Lett. 1999 , 1 , 997 – 1000 ; (b) Calo , V. ; Nacci , A. ; Lopez , L. ; Mannarini , N. Heck reaction in ionic liquids catalyzed by a Pd-benzothiazole carbine complex . Tetrahedron Lett. 2000 , 41 , 8973 – 8976 .
   Web of Science ®Google Scholar
• Potdar , M. K. ; Mohile , S. S. ; Salunkhe , M. M. Coumarin synthesis via Pechmann condensation in Lewis acidic chloroaluminate ionic liquid . Tetrahedron Lett. 2001 , 42 , 9285 – 9287 .
   Web of Science ®Google Scholar
• Peng , J. ; Deng , Y. Ionic liquids catalyzed Biginelli reaction under solvent-free conditions . Tetrahedron Lett. 2001 , 42 , 5917 – 5919 .
   Web of Science ®Google Scholar
• (a) Ren , R. X. ; Zueva , L. D. ; Ou , W. Formation of ϵ-caprolactam via catalytic Beckmann rearrangement using P2O5 in ionic liquids . Tetrahedron Lett. 2001 , 42 , 8441 – 8443 ; (b) Peng , J. ; Deng , Y. Catalytic Beckmann rearrangement of ketoximes in ionic liquids . Tetrahedron Lett. 2001 , 42 , 403 – 405 ; (c) Wasserscheid , P. ; Keim , W. Ionic liquids-new “solvents” for transition metal catalysis . Angew. Chem. Int. Ed. 2000 , 39 , 3772 – 3789 .
   Web of Science ®Google Scholar
• (a) Wang , B. ; Gu , Y. ; Luo , C. ; Yang , T. ; Yang , L. ; Suo , J. Pyrrole synthesis in ionic liquids by Paal-Knorr condensation under mild conditions . Tetrahedron Lett. 2004 , 45 , 3417 – 3419 ; (b) Yadav , J. S. ; Reddy , B. V. S. ; Baishya , G. ; Reddy , K. V. ; Narsaiah , A. V. Conjugate addition of indoles to α,β-unsaturated ketones using Cu(OTf)2 immobilized in ionic liquids . Tetrahedron 2005 , 61 , 9541 – 9544 ; (c) Xu , L. W. ; Li , L. ; Xia , C. G. ; Zhou , S. L. ; Li , J. W. The first ionic liquids promoted conjugated addition of azide ion to α,β-unsaturated carbonyl compounds . Tetrahedron Lett. 2004 , 45 , 1219 – 1221 .
   Web of Science ®Google Scholar
• (a) Shi , D. Q. ; Yang , F. Ionic liquid as an efficient promoting medium for synthesis of bis-pyrazolo[3,4-b:4′,3′-e]pyridines. J. Chin. Chem. Soc. 2008, 55, 755–760; (b) Shi , D. Q. ; Ni , S. N. ; Yang , F. ; Shi , J. W. ; Dou , G. L. ; Li , X. Y. ; Wang , X. S. An efficient synthesis of polyhydroacridine derivatives by the three-component reaction of aldehydes, amines and dimedione in ionic liquid. J. Heterocyclic Chem. 2008, 45, 653–660; (c) Shi , D. Q. ; Ni , S. N. ; Yang , F. ; Shi , J. W. ; Dou , G. L. ; Li , X. L. ; Wang , X. S. ; Ji , S. J. An efficient synthesis of pyrimido[4,5-b]quinoline and indeno[2′,1′:5,6]pyrido[2,3-d]pyrimidine derivatives via multicomponent reactions in ionic liquids. J. Heterocyclic Chen. 2008, 45, 693–702; (d) Shi , D. Q. ; Ni , S. N. ; Yang , F. ; Ji , S. J. An efficient and green synthesis of 3,3′-benzylidenebis (4-hydroxy-6-methylpyridine 2(1H)-one) derivatives through multicomponent reaction in ionic liquid. J. Heterocyclic Chem. 2008, 45, 1275–1280; (e) Shi , D. Q. ; Yang , F. ; Ni , S. N. A facil synthesis of furo[3,4-e]pyrazolo[3,4-b]pyridine-5(7H)-one derivatives via three-component reaction in ionic liquid. J. Heterocyclic Chem. 2009, 46, 469–476; (f) Shi , D. Q. ; Zhou , Y. ; Rong , S. F. Ionic liquid, [bmim]Br as an efficient promoting medium for the synthesis of 3-acetoacetylcoumarin derivatives without the use of any catalyst. Synth. Commun. 2009, 39, 3500–3508.
   Web of Science ®Google Scholar