First synthesis and biological evaluation of indeno[2,1-e]pyrazolo[3,4-b]pyrazin-5-one and related derivatives

Anticancer and Anti-Inflammatory Activities of Some New Pyrazolo[3,4-b]pyrazines

New derivatives of pyrazolo[3,4-b]pyrazines and related heterocycles were synthesized using 5-amino-3-methyl-4-nitroso-1-phenyl-pyrazole (1) as a starting material. The 5-acetyl derivative 15 was shown to be a useful key intermediate for the synthesis of several derivatives of pyrazolopyrazines. Some of the prepared compounds were evaluated for their anti-inflammatory and anti-breast cancer MCF-7 cell line activities. SAR study showed that compounds 15 and 29 exhibited remarkable anti-inflammatory activity, where 15 showed the same activity as that of the reference drug indomethacin. On the other hand, compounds 25i, 25j showed very significant inhibitory activity (p < 0.001) against MCF-7 breast cancer cell line.

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

The condensation of 5-aminopyrazole with various bielectrophilic moieties results in the formation of pyrazoloazines, an interesting array of fused heterocyclic systems. The development of new synthetic routes towards pyrazoloazines for their biological and medicinal exploration is an attractive area for researchers throughout the world. The present review focuses on various synthetic methods developed in the last decade for the synthesis of differently substituted pyrazoloazines by a broad range of organic reactions by means of 5-aminopyrazole as a precursor.

An efficient Synthesis and Photophysical Properties of 1H-pyrazolo-[3,4-b]pyridine and pyrazolo[3,4-b][1,8]naphthyridines

A novel synthon 6-amino-3-(4-methoxyphenyl)-1-phenyl-1H-pyrazolo[3,4-b] pyridine-5-carbaldehyde 4 was synthesized by multistep process. Then Friedlander condensation of this synthon with reactive methylenes was performed to achieve interesting tricyclic 6a-b, tetracyclic 6d and pentacyclic 6c N-heterocycles in excellent yield. The absorption and emission spectra of compounds 1-4 and 6 were measured and observed that the absorption and emission depends on the substituent at C-6 and C-7 position of pyridine ring in naphthyridines skeleton 6.

Crystal structure of 2-[12-methyl-14-phenyl-10,13,14,16-tetra-aza-tetra-cyclo[7.7.0.0(2,7).0(11,15)]hexa-deca-1(16),2,4,6,9,11(15),12-heptaen-8-yl-idene]propandi-nitrile

In the title mol-ecule, C22H12N6, the fused tetracyclic core shows a small lengthwise twist as indicated by the dihedral of 2.7 (2)° between the outer rings. In the crystal, mol-ecules stack along the b-axis direction via offset π-stacking [centroid-centroid distances = 3.5282 (13) and 3.5597 (14) Å] with the stacks weakly associated through C-H⋯N hydrogen bonds. The phenyl ring is rotationally disordered over two orientations with an occupancy ratio of 0.516 (4):0.484 (4).

Crystal structure of 5-(4,5-di-hydro-1H-imidazol-2-yl)-3-methyl-1-phenyl-1H-pyrazolo-[3,4-b]pyrazin-6-amine

In the title compound, C15H15N7, the phenyl ring is inclined by 19.86 (5)° to the mean plane of the pyrazolo-[3,4-b]pyrazine core. In the crystal, N-H⋯N and C-H⋯N hydrogen bonds form [010] chains, which stack via π-π inter-actions [centroid-centroid distance between the pyrazole rings = 3.4322 (7) Å].

Progress of the synthesis of condensed pyrazole derivatives (from 2010 to mid-2013)

Condensed pyrazole derivatives are important heterocyclic compounds due to their excellent biological activities and have been widely applied in pharmaceutical and agromedical fields. In recent years, numerous condensed pyrazole derivatives have been synthesized and advanced to clinic studies with various biological activities. In this review, we summarized the reported synthesis methods of condensed pyrazole derivatives from 2010 until now. All compounds are divided into three parts according to the rings connected to pyrazole-ring, i.e. [5, 5], [5,F 6], and [5, 7]-condensed pyrazole derivatives. The biological activities and applications in pharmaceutical fields are briefly introduced to offer an orientation for the design and synthesis of condensed pyrazole derivatives with good biological activities.