Phenolic-rich extracts from S. montana were obtained by continuous Soxhlet extraction following with liquid–liquid extraction clean-up and partial chemical modification with diazomethane. Eight extracts were subjected for quantification of total phenolic and flavonoid content, as well as for testing of their antioxidant activity. In general, chemically modified extracts showed better antioxidant activity than the natural ones.
Three new 1,2,3-triazole-based ligands with an N,N,N coordination core were prepared using a convergent synthetic protocol starting from racemic 2-amino-1-phenylethanol. They were tested as chelators for biorelevant Zn(II) or Ni(II) ions. An N,N,N ligand with a terminal amino functionality coordinated the Zn(II) in a bidentate fashion, not including the triazole nitrogen. The ligand with two pendant 2-pyridyl groups acted as a tridentate ligand without an N2-triazole coordination to Zn(II), while the ligand containing one 2-pyridyl group acted as an inverse-click chelator for Ni(II) ions.
1,5-Disubstituted-4-oxo-4,5-dihydro-1H-pyrazolo[4,3-c]pyridine-7-carboxamides functionalized at positions 1, 5, and 7 were prepared in six straightforward steps from cheap, commercially available dialkyl acetone-1,3-dicarboxylate. Due to the instability of methyl 1-benzyl-substituted pyrazolo[4,3-c]pyridine-7-carboxylates under basic hydrolytic conditions (LiOH/H2O), a detour via the corresponding benzyl esters was introduced to deliver the final 1-benzyl-substituted-bicyclic carboxamides in seven steps. The designed synthetic route is suitable for the construction of a larger library of compounds.
Synthesis and catalyst performance of 2,3- (type B, C) and 2,8-disubstituted (type D) thiourea bifunctional organocatalysts was attempted. The synthesis of catalyst of type B has, so far, not been realized, while catalysts of type C, i.e., the 2,3-exo- and the 2-endo-3-exo-thiourea catalysts, were prepared in six steps starting from (+)-camphor. The catalysts of type D were prepared from (+)-camphor in eight steps. All the potential catalysts as well as most of the intermediate products were carefully structurally characterized. The thiourea bifunctional organocatalysts were tested in a model reaction of Michael addition of dimethyl malonate to trans-β-nitrostyrene.
Two variants of the synthesis of 6-alkyl-7-oxo-4,5,6,7-tetrahydropyrazolo[1,5-c]pyrimidine-3-carboxamides have been developed. The first pathway comprises nine steps starting with the introduction of the 6-alkyl group (R1) via addition of a primary alkylamine to methyl acrylate followed by a seven-step transformation into the 6-benzyl-7-oxo-4,5,6,7-tetrahydropyrazolo[1,5-c]pyrimidine-3-carboxylic acid, which is then amidated into title compounds. The other variation is based on an analogous four-step transformation of Boc-β-alanine into a 6-unsubstituted benzyl ester as the key intermediate. The 6-alkyl group (R1) is then introduced by N-alkylation with alkyl halides, followed by O-debenzylation to give the carboxylic acids, and amidation. A library of 18 title carboxamides was prepared in very good yields.