Dihydropyrrolo[3,4-c]pyrazoles

(E)-3,3′-(Diazene-1,2-diyl)bis(1-methyl-1,4,5,6-tetrahydropyrrolo[3,4-c]pyrazol-5-ium) dinitrate dihydrate

The title compound, C₁₂H₁₈N₈²⁺·2NO₃⁻·2H₂O, was synthesized unexpectedly from 3-amino-1-methyl-1,4,5,6-tetra­hydro­pyrrolo­[3,4-c]pyrazol-5-ium chloride and cerium(IV) ammonium nitrate. The cation has a crystallographically imposed centre of symmetry. In the crystal, the ions and water mol­ecules are linked via O—H⋯N, N—H⋯O and O—H⋯O hydrogen bonds into a three-dimensional network.

5-tert-Butyl 1-ethyl 3-amino-1,4,5,6-tetrahydropyrrolo[3,4-c]pyrazole-1,5-dicarboxylate

The asymmetric unit of the title compound, C₁₃H₂₀N₄O₄, contains two crystallographically independent mol­ecules in which the dihedral angles between the fused pyrrole and pyrazole rings are 5.06 (8) and 1.12 (8)°. In the crystal, mol­ecules are linked by inter­molecular N—H⋯O and N—H⋯N hydrogen bonds into chains parallel to the b axis.

3-(5-Chloronaphthalene-1-sulfonamido)-2-(2-hydroxyethyl)-4,5,6,7-tetrahydro-2H-pyrazolo[4,3-c]pyridin-5-ium chloride

In the cation of the title compound, C₁₈H₂₀ClN₄O₃S⁺·Cl⁻, the tetra­hydro­pyridinium ring assumes a half-chair conformation. The dihedral angle between the pyrazole ring and the naphthalene ring system is 75.19 (6)°. In the crystal, ions are linked into a three-dimensional network by N—H⋯O, N—H⋯Cl and O—H⋯Cl hydrogen bonds and weak π–π stacking inter­actions with centroid–centroid distances of 3.608 (2) Å.

Synthesis and in vitro antibacterial activity of 7-(3-amino-6,7-dihydro-2-methyl-2H-pyrazolo[4,3-c] pyridin-5(4H)-yl)fluoroquinolone derivatives

A series of novel 7-(3-amino-6,7-dihydro-2-methyl-2H-pyrazolo[4,3-c]pyridin- 5(4H)-yl)fluoroquinolone derivatives were designed, synthesized and characterized by 1H-NMR, MS and HRMS. These fluoroquinolones were evaluated for their in vitro antibacterial activity against representative Gram-positive and Gram-negative strains. Results reveal that most of the target compounds exhibit good growth inhibitory potency against methicillin-resistant Staphylococcus epidermidis (MRSE) (MIC: 0.25-4 μg/mL) and Streptococcus pneumoniae (MIC: 0.25-1 μg/mL). In addition, compound 8f is 8-128 fold more potent than the reference drugs gemifloxacin (GM), moxifloxacin (MX), ciprofloxacin (CP) and levofloxacin (LV) against methicillin-resistant Staphylococcus aureus 10-05 and Streptococcus hemolyticus 1002 and 2-64 fold more active against methicillin-sensitive Staphylococcus aureus 10-03 and 10-04.

tert-Butyl 3-amino-2-methyl-6,7-dihydro-2H-pyrazolo[4,3-c]pyridine-5(4H)-carboxyl-ate

In the mol-ecule of the title compound, C(12)H(20)N(4)O(2), the dihydro-piperidine ring assumes a half-chair conformation. In the crystal, cllassical N-H⋯O and N-H⋯N inter-molecular hydrogen bonds link mol-ecules into double chains along the a axis.