Search Results (5)

Macrocyclic compounds, including macrolactones and macrodiolides, play a significant role in the development of supramolecular chemistry, materials science, the perfume industry, and pharmaceuticals. In previous studies conducted by our group over several years, previously undescribed macrocyclic compounds containing pharmacophoric 1Z,5Z- diene fragments in their structure were synthesized for the first time, which showed high potential in studies on cytotoxicity, apoptosis-inducing activity, effects on the cell cycle, and mitochondria in tumor cell lines (Jurkat, K562, U937). As part of the continuing research on the development of methods for synthesizing new unsaturated macrodiolides and studying their antitumor properties, this work presents, for the first time, the stereoselective synthesis of macrocyclic compounds based on 1,14 -tetradeca-5Z,9Z-dienoic acid and α,ω-alka-nZ, (n + 4)Z-dienediols (1,12-dodeca-4Z,8Z-dienediol, 1,14-tetradeca-5Z,9Z-dienediol, 1,16-octadeca-6Z,10Z-dienediol) in good yields. The method for the synthesis of new macrodiolides is based on the previously well-proven reaction of direct intermolecular cyclocondensation of dienedioic acid with diene diols in the presence of 5 mol.% hafnium(IV) triflate. As a result of the experiments, it was shown that the reaction between 1,14-tetradeca-5Z,9Z-dienedioic acid and 1,16-octadeca-6Z,10Z-dienediol in toluene proceeded within 18 h with the highest yield of 76%, with the formation of previously undescribed tetraenoic macrodiolides containing two 1Z,5Z-diene fragments in their structure. Full article

Hafnium(IV) triflate (Hf(OTf)₄) has been identified as a potent catalyst for the direct three-component synthesis of β-carbamate ketones. This new method, featuring a low catalyst loading, fast reaction rate, and solvent-free conditions, provided facile access to a diversity of carbamate-protected Mannich bases. A mechanistic investigation indicated that the three-component reaction proceeds via sequential aldol condensation and aza-Michael addition, but not the Mannich-type pathway. Full article

Efficient methods have been developed for synthesizing previously unknown macrodiolides incorporating 1Z,5Z-diene and 1,3-diyne moieties in 54–84% yields and with >98% stereoselectivity by means of the intermolecular cyclocondesation of (7Z,11Z)-octadeca-7,11-dienedioic acid with α,ω-diols catalyzed by hafnium triflate Hf(OTf)₄ as well as via the oxidative coupling of α,ω-diynes obtained by the esterification of (7Z,11Z)-octadeca-7,11-dienedioic acid with alkynols. The synthesized macrodiolides exhibit cytotoxic activity toward the Jurkat, K562, U937, HL-60, HeLa, and Hek293 cell lines in vitro. Full article

Hf(OTf)₄ was identified as a highly potent catalyst (0.1–0.5 mol%) for three-component Mannich reaction under solvent-free conditions. Hf(OTf)₄-catalyzed Mannich reaction exhibited excellent regioselectivity and diastereoselectivity when alkyl ketones were employed as substrates. ¹H NMR tracing of the H/D exchange reaction of ketones in MeOH-d₄ indicated that Hf(OTf)₄ could significantly promote the keto-enol tautomerization, thereby contributing to the acceleration of reaction rate. Full article

In our studies on the catalytic activity of Group IVB transition metal Lewis acids, Hf(OTf)₄ was identified as a highly potent catalyst for ”one-pot, three-component” Biginelli reaction. More importantly, it was found that solvent-free conditions, in contrast to solvent-based conditions, could dramatically promote the Hf(OTf)₄-catalyzed formation of 3,4-dihydro-pyrimidin-2-(1H)-ones. To provide a mechanistic explanation, we closely examined the catalytic effects of Hf(OTf)₄ on all three potential reaction pathways in both “sequential bimolecular condensations” and “one-pot, three-component” manners. The experimental results showed that the synergistic effects of solvent-free conditions and Hf(OTf)₄ catalysis not only drastically accelerate Biginelli reaction by enhancing the imine route and activating the enamine route but also avoid the formation of Knoevenagel adduct, which may lead to an undesired byproduct. In addition, ¹H-MMR tracing of the H-D exchange reaction of methyl acetoacetate in MeOH-d₄ indicated that Hf(IV) cation may significantly accelerate ketone-enol tautomerization and activate the β-ketone moiety, thereby contributing to the overall reaction rate. Full article