Pyrazolopyridines synthesis

Pyrazolo[l,5-a]pyridine-2,3-dicarboxylic acid dimethyl ester synthesis, 5, 153 Pyrazolopyridines acylation, 5, 311 6-fused... 

Similarly, Yli-Kauhaluoma and co-workers have studied the 1,3-dipolar cycloaddition of polymer-bound alkynes to azomethine imines, generated in situ from A-ami nopyridine iodides, in the synthesis of pyrazolopyridines <06JCC344>. 

In previous work (85MI1 87AHC319), the synthesis and chemistry of pyrazolopyridines and pyrazolopyrimidines was surveyed. This chapter reports synthetic approaches to other aromatic 10 tt electron systems containing a pyrazole moiety, as well as the systems main chemical and physicochemical properties. 

Scheme 15 Synthesis of positional isomers of pyrazolopyridine carboxylic acid derivatives...

A practical method for the synthesis of chiral pyridazinone bearing a pyrazolopyridine ring via lipase-catalyzed resolution of 2-(acyloxymethyl)-4,5-dihydro-5-methylpyridazin-3(2H)-one derivatives 113 was reported by Yoshida et al.95... 

New pyrazolopyridine derivatives have been synthesized <03SC253>, <03BMCL3367>, <03J1C311>. An elegant one-step synthesis of 5,6-disubstituted isoxazolo[4,5-fc]pyridine N-oxides has been carried out <03SC3077>. 

Warshakoon NC, Wu S, Boyer A, Kawamoto R, Renock S, Xu K, Pokross M, Evdokimov AG, Zhou S, Winter C, Walter R, Mekel M. Design and synthesis of a series of novel pyrazolopyridines as HIF-1 alpha prolyl hydroxylase inhibitors. Bioorg. Med. Chem. Lett. 2006 16 5687-5690. 

Pyrazolopyridines, general review 84AHC(36)343. 6H-Pyrido[4,3-h]carbazoles, synthesis of 84S289. 

Another interesting MW-assisted MCR for construction of the DHP ring as part of a more complex bicyclic scaffold was reported by Quiroga et al. They realized the MW-assisted synthesis of both pyrazolopyridines 7 and pyrido[2,3-d]pyrimidines 8 under solvent-free conditions (Scheme 17.8) [38]. 

An interesting synthesis of pyrazolopyridines has been presented by Alvarez-Builla (02S1093), using an intramolecular radical addition by the 3-pyridyl radical derived from 76a-d (Scheme 14) as well as 2-p5u-azinyl radicals to a p5uidine ring, with subsequent rearomatisation to produce cyclised products 77a-c (Scheme 17). 

In 2013, Neres and coworker reported the synthesis, biochemical, and microbiological evaluation of a series of pyrazolopyridine derivatives as normucleoside inhibitors of BasE, an adenylating enzyme in the sidero-phore biosynthetic pathway of the opportunistic pathogen Acinetobacter baumannii. The amino-pyrazolopyridine series was produced via direct... 

K. Haiju, 1. Kylanlahti, T. Paananen, M. Polamo, J. Nielsen, J. Yli-Kauhaluoma, Solid-phase synthesis of pyrazolopyridines from polymer-bound alkyne and azomethine imines. J. Comb. Chem. 2006, 8, 344-349. 

Pyrazolopyridine kinase inhibitors, containing 3,5-difluoropyridine fragment 201 were prepared by multistep synthesis. Three-component reaction of trifluoro-pyridylpyridopyrazole (196), 3-methyl-2-(piperazin-2-yl)butan-2-ol (197) and 1-trimethylsilylimidazole (198) proceeded with formation of a mixture isomers 199 (R, S) and 200 (R, R). The reaction of isomer 199 (R, S) with TBAF in THF gives target compound 201 having (R, S) configuration [127] (Scheme 62). 

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