A facile synthesis of 4-acylamino-tetrahydroindazoles via the Ritter reaction

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 structures of two (±)-exo-N-isobornyl-acetamides

The title compounds consist of a 1,7,7-tri­methylbi­cyclo­[2.2.1]heptane (bornane or camphane) skeleton which is decorated with acetamide for (±)-(1) and chloro­acetamide for (±)-(2), functionalities. In the crystals of both compounds, mol­ecules are linked via N—H⋯O hydrogen bonds, reinforced by C—H⋯O contacts, forming chains propagating along the a axis.

The title compounds consist of a bornane skeleton with attached acetamide, C₁₂H₂₁NO (±)-(1) {systematic name: (±)-N-[(1RS,2RS,4RS)-1,7,7-tri­methylbi­cyclo­[2.2.1]heptan-2-yl]acetamide}, and chloro­acetamide, C₁₂H₂₀ClNO (±)-(2) {systematic name: (±)-2-chloro-N-[(1RS,2RS,4RS)-1,7,7-tri­methylbi­cyclo­[2.2.1]heptan-2-yl]­acetamide}, functionalities to the 2-exo-position. The crystal structure of the first monoclinic polymorph of (±)-(1) has been reported previously [Ung et al. (2014 ▸). Monatsh. Chem.145, 983–992]. Compound (±)-(1) crystallizes in the space group P2₁/n with two independent mol­ecules in the asymmetric unit, in contrast to the above-mentioned polymorph which crystallized in the space group C2/c with one mol­ecule in the asymmetric unit. In the title compounds, the bicyclic bornane moieties have normal geometries. In the crystals of both compounds, mol­ecules are linked by N—H⋯O hydrogen bonds, reinforced by C—H⋯O contacts, forming trans-amide chains propagating along the a-axis direction. In the case of compound (±)-(1), neighbouring chains are linked by further C—H⋯O contacts, forming double-chain ribbons along [100].

One-pot protocol to synthesize N-(β-nitro)amides by tandem Henry/Ritter reaction

A novel, efficient and atom economical one pot protocol for the synthesis of N-(β-nitro)amides has been described by combining the Henry reaction with the Ritter reaction.