Resolution, absolute configuration, and synthetic transformations of 7-amino-tetrahydroindazolones

Crystal structure of 3,6,6-trimethyl-4-oxo-1-(pyridin-2-yl)-4,5,6,7-tetra-hydro-1H-indazol-7-aminium chloride and its monohydrate

The title compounds, C15H19N4O+·Cl- and C15H19N4O+·Cl-·H2O, obtained in attempts to synthesize metal complexes using tetra-hydro-indazole as a ligand, were characterized by NMR, IR and X-ray diffraction techniques. The partially saturated ring in the tetra-hydro-indazole core adopts a sofa conformation. An intra-molecular N-H⋯N hydrogen bond formed by the protonated amino group and the N atom of the pyridyl substituent is found in the first structure. In the hydro-chloride, the organic moieties are linked by two N-H⋯Cl- hydrogen bonds, forming a C(4) graph-set. In the hydrate crystal, a Cl- anion and a water mol-ecule assemble the moieties into infinite bands showing hydrogen-bond patterns with graph sets C(6), R64(12) and R42(8). Organic moieties form π-π stacked supra-molecular structures running along the b axis in both structures.

Synthesis of novel lupane triterpenoid-indazolone hybrids with oxime ester linkage

An efficient protocol for the synthesis of novel lupane triterpenoid-indazolone hybrids with oxime ester linkage has been developed from naturally accessible precursor betulin. For the first time a series of betulonic acid-indazolone hybrids have been synthesized via an acylation of corresponding 6,7-dihydro-1H-indazol-4(5H)-one oximes with betulonic acid chloride. Diastereoselective reduction of the obtained betulonic acid conjugates with NaBH₄ resulted in a formation of betulinic acid-indazolone hybrids in excellent yields. The configuration of the key compounds has been fully established by X-ray and 2D NMR analysis.

Crystal structure of 3-O-benzyl-4(R)-C-(1-benzyl-1H-1,2,3-triazol-4-yl)-1,2-O-isopropylidene-α-D-erythrofuranose

The title compound is a substituted 2,2-di­methyl­tetra­hydro­furo[2,3-d][1,3]dioxole. The furan­ose ring adopts an envelope conformation, close to C₃-exo, as does the fused dioxolane ring. In the crystal, mol­ecules are linked by weak C—H⋯O hydrogen bonds, forming zigzag chains along [010].

The title compound, C₂₃H₂₅N₃O₄, {systematic name: 1-benzyl-4-[(3aR,5R,6R,6aR)-6-benz­yloxy-2,2-di­methyl­tetra­hydro­furo[2,3-d][1,3]dioxol-5-yl]-1H-1,2,3-triazole}, consists of a substituted 2,2-di­methyl­tetra­hydro­furo[2,3-d][1,3]dioxole. The furan­ose ring adopts an envelope conformation close to C₃-exo, where the C atom substituted by the benz­yloxy group is the flap. The fused dioxolane ring also adopts an envelope conformation, with the methyl­ene C atom as the flap. In the crystal, mol­ecules are linked by weak C—H⋯O hydrogen bonds, forming zigzag chains along [010].