Search Results (9)

The cyclization of propargyl alcohols with CO₂ represents a highly significant method for the utilization of CO₂. The resulting cyclic carbonates possesses high chemical value and hold great potential for applications in battery electrolytes, polymer precursors, and pharmaceutical intermediates. However, most existing reports on this cyclization have been limited to simple propargyl alcohol substrates that are substituted with inert alkyl, cycloalkyl, and phenyl groups. For functionalized propargyl alcohols, such as alkyne-1,2-diols, only a single report has been documented thus far. In this study, we have developed an innovative catalytic system comprising cost-effective copper salts and environmentally friendly ionic liquids (CuCl/1-ethyl-3-methylimidazolium acetate) for the cyclization of alkyne-1,2-diols with CO₂. Compared to the previously reported AgF/bulky monophosphine ligand (BrettPhos) system, our system is free of traditional volatile solvents, phosphine ligands, and additives. Notably, this is the first reported Cu(I)-catalyzed system for this cyclization, offering significant advantages in terms of cost-effectiveness and reduced toxicity compared to silver salts. Moreover, the use of ionic liquids ensures considerable recyclability, further enhancing the sustainability and practicality of this approach. Full article

As an extension of our study of the reactivity of derivatives of 3,3,4,4-tetraethoxybut-1-yne, attempts have been made to achieve acid-catalyzed deacetalization of the diethoxymethyl moieties in 5-diethoxymethyl-1,1,2,2-tetraethoxyundeca-3,6-diyn-5-ol. That was not achieved; instead, only deketalization occurred and afforded the title compound, indicating that the triple bond activates the propargylic diethoxy moiety relative to the other acetal groups. Full article

Marine organisms represent a potential source of secondary metabolites with various therapeutic properties. However, the pharmaceutical industry still needs to explore the algological resource. The species Caulerpa lamouroux Forssk presents confirmed biological activities associated with its major compound caulerpin, such as antinociceptive, spasmolytic, antiviral, antimicrobial, insecticidal, and cytotoxic. Considering that caulerpin is still limited, such as low solubility or chemical instability, it was subjected to a structural modifications test to establish which molecular regions could accept structural modification and to elucidate the cytotoxic bioactive structure in Vero cells (African green monkey kidney cells, Cercopithecus aethiops; ATCC, Manassas, VA, USA) and antiviral to Herpes simplex virus type 1. Substitution reactions in the N-indolic position with mono- and di-substituted alkyl, benzyl, allyl, propargyl, and ethyl acetate groups were performed, in addition to conversion to their acidic derivatives. The obtained analogs were submitted to cytotoxicity and antiviral activity screening against Herpes simplex virus type 1 by the tetrazolium microculture method. From the semi-synthesis, 14 analogs were obtained, and 12 are new. The cytotoxicity assay showed that caulerpin acid and N-ethyl-substituted acid presented cytotoxic concentrations referring to 50% of the maximum effect of 1035.0 µM and 1004.0 µM, respectively, values significantly higher than caulerpin. The antiviral screening of the analogs revealed that the N-substituted acids with methyl and ethyl groups inhibited Herpes simplex virus type 1-induced cytotoxicity by levels similar to the positive control acyclovir. Full article

The carboxylation of unsaturated amine and alcohol compounds, including 4-benzylamino-1-phenyl-1-butyne (homopropargylamine), 2-butyne-1-ol (propargylic alcohol), and 2,3-butadiene-1-ol (allenylmethyl alcohol), using the hydroxidogold(I) complex, AuOH(IPr) [IPr = 1,3-bis(2,6-diisopropylphenyl)-imidazol-2-ylidene], produces corresponding alkenylgold(I) complexes with a cyclic urethane or carbonate framework in high yields. The reaction takes place in aprotic THF at room temperature under the atmospheric pressure of CO₂ in the absence of base additives. The products were characterized by NMR spectroscopy, elemental analysis, and X-ray crystallography. The functionalized alkenyl complexes prepared from the alkynes can be protonated by treatment with an equimolar amount of acetic acid to afford five- or six-membered carboxylation products, whereas the related alkenyl complex derived from allenylmethyl alcohol decomposed to recover the starting allene via ring-opening decarboxylation. Full article

Intramolecular cycloadditions have the great advantage of forming two rings simultaneously. We report the use of intramolecular [3 + 2] cycloaddition of the nitrile oxide derived from an N-propargylbenzimidazole oxime in the synthesis of a hitherto unreported tetracyclic isoxazole-containing ring system bearing “6-5-5-5”-membered ring fusions. The initial condensation was achieved through reaction of o-phenylenediamine with ethyl diethoxyacetate, followed by alkylation with propargyl bromide, deprotection of the acetal to the aldehyde, formation of an aldoxime, and intramolecular nitrile oxide cycloaddition (INOC). Characterization of the aldoxime and tetracyclic isoxazole is included herein. Full article

Two series of hyper-cross-linked microporous polyacetylene networks containing either -[CH=C(CH=O)]- or -[CH=C(CH₂OH)]- monomeric units are reported. Networks are prepared by chain-growth copolymerization of acetal-protected propargyl aldehyde and acetal-protected propargyl alcohol with a 1,3,5-triethynylbenzene cross-linker followed by hydrolytic deprotection/detemplating. Deprotection not only liberates reactive CH=O and CH₂OH groups in the networks but also modifies the texture of the networks towards higher microporosity and higher specific surface area. The final networks with CH=O and CH₂OH groups attached directly to the polyene main chains of the networks have a specific surface area from 400 to 800 m²/g and contain functional groups in a high amount, up to 9.6 mmol/g. The CH=O and CH₂OH groups in the networks serve as active centres for the reversible capture of CO₂ and water vapour. The water vapour capture capacities of the networks (up to 445 mg/g at 297 K) are among the highest values reported for porous polymers, making these materials promising for cyclic water harvesting from the air. Covalent modification of the networks with (R)-(+)-3-aminopyrrolidine and (S)-(+)-2-methylbutyric acid enables the preparation of porous chiral networks and shows networks with CH=O and CH₂OH groups as reactive supports suitable for the anchoring of various functional molecules. Full article

A sequential Rh(III)-catalyzed C-H activation/annulation of N-hydroxybenzamides with propargylic acetates leading to the formation of NH-free isoquinolones is described. This reaction proceeds through a sequential C-H activation/alkyne insertion/intramolecular annulation/N-O bond cleavage procedure, affording a broad spectrum of products with diverse substituents in moderate-to-excellent yields. Notably, this protocol features the simultaneous formation of two new C-C/C-N bonds and one heterocycle in one pot with the release of water as the sole byproduct. Full article

With the aim of profitable conversion of carbon dioxide (CO₂) in an efficient, economical, and sustainable manner, we developed a CuBr/ionic liquid (1-butyl-3-methylimidazolium acetate) catalytic system that could efficiently catalyze the three-component reactions of propargylic alcohols, 2-aminoethanols, and CO₂ to produce 2-oxazolidinones and α-hydroxy ketones. Remarkably, this catalytic system employed lower metal loading (0.0125–0.5 mol%) but exhibited the highest turnover number (2960) ever reported, demonstrating its excellent activity and sustainability. Moreover, our catalytic system could efficiently work under 1 atm of CO₂ pressure and recycle among the metal-catalyzed systems. Full article

A novel consecutive three-component synthesis of 3-(hetero)aryl-1H-pyrazoles via room temperature Sonogashira arylation of propynal diethylacetal used as a propargyl aldehyde synthetic equivalent has been disclosed. The final acetal cleavage-cyclocondensation with hydrazine hydrochloride at 80 °C rapidly furnishes the title compounds in a one-pot fashion. Full article