Synthesis and biological evaluation of 3,6-diamino-1H-pyrazolo[3,4-b]pyridine derivatives as protein kinase inhibitors

One-pot three-component synthesis of pyrano [3,2-b]pyrazolo[4,3-e]pyridin-8(1H)-ones

An efficient one-pot synthesis of novel pyrano[3,2-b]pyrazolo[4,3-e]pyridin-8(1H)-ones via three-component condensation of kojic acid, 1-H-pyrazol-5-amines and aldehydes in the presence of a catalytic amount of Zn(OTf)(2) followed by H(2)O(2)-mediated oxidation is reported. Furthermore, the synthesis of 1'H-spiro[indoline-3,4'-pyrano[2,3-b]pyrazolo[3,4-e]pyridine]-2,8'(9'H)-diones were chosen for the library validation.

A Facile Synthesis of Pyrido[2′,3′:3,4]pyrazolo[1,5-a]pyrimidine and Pyrido[2′,3′:3,4]pyrazolo[5,1-c][1,2,4]triazine Bearing a Thiophene Moiety

Pyridinone derivative8was synthesized and transformed into the respective chloropyridine9, which was allowed to react with hydrazine hydrate to afford pyrazolo[3,4-b]pyridin-3-amine derivative11. Compound11was used as a key intermediate for a facile synthesis of the title compounds14,15,17,21a,b, and24a–cwhere the reaction of11with some 1,3-dielecrophiles resulted in the formation of pyrido[2′,3′:3,4]pyrazolo[1,5-a]pyrimidines14,15, and17, whereas diazotization of compound11gave the respective diazonium salt18which was coupled with some active methylene-containing compounds to give the corresponding hydrazones19a,band22a–c. Cyclization of the latter hydrazones yielded the pyrido[2′,3′:3,4]pyrazolo[5,1-c][1,2,4]triazines21a,band24a–c, respectively.

Synthesis of 2,6'-dioxo-1',5',6',7'-tetrahydrospiro[indoline-3,4'-pyrazolo[3,4-b]pyridine]-5'-carbonitriles via a one-pot, three-component reaction in water

A one-pot, three-component condensation reaction of an isatin, aminopyrazole, and alkyl cyanoacetate in water to give 2,6'-dioxo-1',5',6',7'-tetrahydrospiro[indoline-3,4'-pyrazolo[3,4-b]pyridine]-5'-carbonitrile with good yields, at 90 °C, using a Et(3)N as catalyst, is described.

Recent advances in the design, synthesis, and biological evaluation of selective DYRK1A inhibitors: a new avenue for a disease modifying treatment of Alzheimer's?

With 24.3 million people affected in 2005 and an estimated rise to 42.3 million in 2020, dementia is currently a leading unmet medical need and costly burden on public health. Seventy percent of these cases have been attributed to Alzheimer's disease (AD), a neurodegenerative pathology whose most evident symptom is a progressive decline in cognitive functions. Dual specificity tyrosine phosphorylation regulated kinase-1A (DYRK1A) is important in neuronal development and plays a variety of functional roles within the adult central nervous system. The DYRK1A gene is located within the Down syndrome critical region (DSCR) on human chromosome 21 and current research suggests that overexpression of DYRK1A may be a significant factor leading to cognitive deficits in people with Alzheimer's disease (AD) and Down syndrome (DS). Currently, treatment options for cognitive deficiencies associated with Down syndrome, as well as Alzheimer's disease, are extremely limited and represent a major unmet therapeutic need. Small molecule inhibition of DYRK1A activity in the brain may provide an avenue for pharmaceutical intervention of mental impairment associated with AD and other neurodegenerative diseases. We herein review the current state of the art in the development of DYRK1A inhibitors.

Catalyst-free synthesis of quinazolin-4-ones from (hetero)aryl-guanidines: application to the synthesis of pyrazolo[4,3-f]quinazolin-9-ones, a new family of DYRK1A inhibitors

A small library of heterocycle-fused quinazolin-4-ones was prepared and evaluated as kinase inhibitors. The key step of the two-step process involves the environmental friendly thermolysis of N-ethoxycarbonyl-N'-(hetero) arylguanidines at 130 °C in water. The cyclization is fully regioselective. The most active molecules, 7-(2-hydroxyethylamino)- and 7-(3-hydroxypropylamino)-pyrazolo[4,3-f]quinazolin-9-ones, inhibit DYRK1A and CLK1 at submicromolar concentrations, indicating the potential interest of this new heterocycle in drug design.

Regioselective acylation of congeners of 3-amino-1H-pyrazolo[3,4-b]quinolines, their activity on bacterial serine/threonine protein kinases and in vitro antibacterial (including antimycobacterial) activity

It was found by virtual screening that 3-amino-1H-pyrazolo[3,4-b]quinolines could have wide protein kinase inhibitory activity. Amides of titled amines and thioureas were synthesized regioselectively. 3-Amino-7-methoxy-1H-pyrazolo[3,4-b]quinoline demonstrated in vitro significant inhibitory activity on bacterial serine/threonine protein kinases (inhibition of resistance to kanamycin in Streptomyces lividans regulated by protein kinases). The studies of Structure Activity Relationship (SAR) showed that the substitution of the NH2 group and 1-NH of pyrazole ring or aromatic ring at the position 6 decreased or removed inhibitory activity.

GSK-3 Inhibitors: Preclinical and Clinical Focus on CNS

Inhibiting glycogen synthase kinase-3 (GSK-3) activity via pharmacological intervention has become an important strategy for treating neurodegenerative and psychiatric disorders. The known GSK-3 inhibitors are of diverse chemotypes and mechanisms of action and include compounds isolated from natural sources, cations, synthetic small-molecule ATP-competitive inhibitors, non-ATP-competitive inhibitors, and substrate-competitive inhibitors. Here we describe the variety of GSK-3 inhibitors with a specific emphasis on their biological activities in neurons and neurological disorders. We further highlight our current progress in the development of non-ATP-competitive inhibitors of GSK-3. The available data raise the hope that one or more of these drug design approaches will prove successful at stabilizing or even reversing the aberrant neuropathology and cognitive deficits of certain central nervous system disorders.

Synthesis and pharmacological assessment of diversely substituted pyrazolo[3,4-b]quinoline, and benzo[b]pyrazolo[4,3-g][1,8]naphthyridine derivatives

The synthesis and pharmacological analyses of a number of pyrazolo[3,4-b]quinoline and benzo[b]pyrazolo[4,3-g][1,8]naphthyridine derivatives are reported. We have synthesized the diversely substituted tacrine analogues 1-6, by Friedländer-type reaction of readily available o-amino-1-methyl-pyrazole-dicarbonitriles with cyclohexanone. The biological evaluation showed that pyrazolotacrines 1-6 are inhibitors of Electrophorus electricus acetylcholinesterase (EeAChE), in the micromolar range, and quite selective in respect to serum horse butyrylcholinesterase (eqBuChE) inhibition; the most interesting inhibitor is N-(5-amino-1-methyl-6,7,8,9-tetrahydro-1H-benzo[b]pyrazolo[4,3-g][1,8]naphthyridin-3-yl)acetamide (5) [IC(50) (EeAChE) = 0.069 ± 0.006 μM; IC(50) (eqBuChE) = 6.3 ± 0.6 μM]. Kinetic studies showed that compound 5 is a mixed-type inhibitor of EeAChE (K(i) = 155 nM). Inhibitor 5 showed a 45% neuroprotection value against rotenone/oligomycin A-induced neuronal death.

Synthesis of Pyrazolo[3,4-b]Pyridine and Pyrido[2′,3′:3,4]Pyrazolo [1,5-a]Pyrimidine Derivatives

The synthesis of two series of 1-phenyl and 1 H-pyrazolo[3,4- b]pyridine is described. Thus, reacting 5-amino-1-phenylpyrazole with chalcone analogues gave 4,6-diarylpyrazolo[3,4- b]pyridine derivatives. While, reacting the same starting material with benzylidene derivatives of ethyl cyanoacetate and malononitrile resulted in 4-oxo and 4-aminopyrazolo[3,4- b]pyridine derivatives, respectively. The synthesis of 3-amino-4,6-diarylpyrazolo[3,4- b]pyridines starting from pyridine was also described. Thus, chlorination of 4,6-diarylpyridone derivatives and their subsequent cyclisation with hydrazine hydrate afforded 3-amino-4,6-diarylpyrazolo[3,4 -b]pyridines. Reaction of the latter compounds with acetylacetone, ethyl ethoxymethylenecyanoacetate and chalcone analogue gave the tricyclic pyrido[2′,3′: 3,4]pyrazolo[1,5- a]pyrimidines. The structures of the products were confirmed by spectral data.

Synthesis of multicyclic pyridine and quinoline derivatives via intramolecular C-H bond functionalization

An efficient method is reported for the preparation of multicyclic pyridines and quinolines by a rhodium-catalyzed intramolecular C-H bond functionalization process. The method shows good scope for branched and unbranched alkyl substituents on the pyridine ring and at the R position of the tethered alkene group. Starting materials capable of undergoing olefin isomerization to provide terminal 1,1-disubstituted alkenes also proved to be effective substrates.

Design and synthesis of 1,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles and pyrazolo[3,4-b]pyridines for Aurora-A kinase inhibitors

Two series of 3-aminopyrazole compounds including 24 1,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles and 16 pyrazolo[3,4-b]pyridines were synthesized and evaluated against HCT116, A549, and A2780 tumor cell lines. Among them, three compounds were found to have the ideal anti-proliferative activities in vitro. Docking experiments showed that the novel pyrazolo[3,4-b]pyridines share the similar interaction mode with Aurora-A kinase as PHA739358.