Search results for "combinatorial"
showing 10 items of 1208 documents
Synthesis of 4-amino-5-fluoropyrimidines and 5-amino-4-fluoropyrazoles from a β-fluoroenolate salt
2020
A synthesis of fluorinated pyrimidines under mild conditions from amidine hydrochlorides and the recently described potassium 2-cyano-2-fluoroethenolate was developed. A broad substrate scope was tested and mostly excellent yields were obtained. The synthesis of fluorinated aminopyrazoles from the same fluorinated precursor could be demonstrated but proceeded with lower efficiency.
Susceptibility of Methyl 3-Amino-1H-pyrazole-5-carboxylate to Acylation
2009
Abstract In the search for a new method of synthesis of hybrid peptides with aminopyrazole carboxylic acid, we tried to force selective acylation at the aromatic amino group instead of at the ring nitrogen atom with fairly gentle acylating agents. The acylating agents used were acid anhydrides: acetic anhydride, tert-butyl pyrocarbonate, and 2-(2-methoxyethoxy)ethoxyacetic acid/dicyclohexylcarbodiimide. We succceded in acylation at this amino group with almost none at the ring nitrogen atom. Sometimes, however, acylation in small quantities at the ring nitrogen atom was observed as a by-product. To remove this by-product, imidazole was used. Thus, we were able to obtain the hybrid peptides …
Multicomponent Synthesis of Benzothiophen-2-acetic Esters by a Palladium Iodide Catalyzed S-cyclization – Alkoxycarbonylation Sequence
2021
A catalytic carbonylative approach to the multicomponent synthesis of benzothiophene derivatives from simple building blocks [1-(2-(methylthio)phenyl)prop-2-yn-1-ols, carbon monoxide, and an alcohol)] is presented. It is based on an S-cyclization-demethylation-alkoxycarbonylation-reduction sequence promoted by the PdI2/KI catalytic system, occurring under relatively mild conditions (40 atm, 80 °C, 15 h). Benzothiophene-2-acetic esters are obtained in moderate to good yields (35–70%) starting from variously substituted substrates in combination with different alcohols as external nucleophiles (17 examples). (Figure presented.).
Methyl-Substituted α-Cyclodextrin as Affinity Material for Storage, Separation, and Detection of Trichlorofluoromethane
2018
Abstract The severely ozone‐depleting trichlorofluoromethane is still appearing in several recycling processes or industrial applications. A simple and selective supramolecular complex formation of per‐methylated α‐cyclodextrin (1) with the highly volatile trichlorofluoromethane (2) is reported. This interaction moreover leads to thermally stable crystals. Per‐methylated α‐cyclodextrin is successfully exploited as a reversible and selective adsorption material for liquid and airborne trichlorofluoromethane as well as an affinity material for the chemical sensing and detection of this particular volatile organic component.
Efficient energy transfer in a tri-chromophoric dyad containing BODIPYs and corrole based on a truxene platform
2018
A star-shaped molecule was designed and synthesized based on a known central truxene platform. Two BODIPY derivatives and one corrole macrocycle were introduced and connected to the 2, 7 and 12-positions of the truxene unit by Suzuki coupling. The dyad was fully characterized by UV-vis absorption, proton nuclear magnetic resonance, mass spectrometry. The direction of energy transfer upon electronic excitation was explored, and the star-shaped molecule system exhibits a highly efficient photoinduced energy transfer process from the excited BODIPY part to the corrole unit.
Post-synthetic methods for functionalization of imidazole-fused porphyrins
2018
Several methods for the post-synthetic modification of imidazo[4,5-[Formula: see text]]porphyrins are reported. First, a synthetic approach to the isomeric difunctionalized porphyrins, containing two [Formula: see text]-fused 2-aryl-1[Formula: see text]-imidazole cycles at adjacent or opposite pyrrole rings of the macrocycle is developed. The core chemistry of this synthetic route is the transformation of 2-aryl-1[Formula: see text]-imidazo[4,5-[Formula: see text]]porphyrins into corresponding imidazodioxochlorins followed by Debus–Radziszewski condensation with aromatic aldehyde. Next, 2-(4-bromophenyl)-1[Formula: see text]-imidazo[4,5-[Formula: see text]]-5,10,15,20-tetramesitylporphyrin…
ChemInform Abstract: 1,2,3-Triazole in Heterocyclic Compounds, Endowed with Biological Activity, Through 1,3-Dipolar Cycloadditions
2014
1,3-Dipolar cycloaddition reactions can be considered a powerful synthetic tool in the building of heterocyclic rings, with applications in different fields. In this review we focus on the synthesis of biologically active compounds possessing the 1,2,3-triazole core through 1,3-dipolar cycloaddition reactions. The 1,2,3-triazole skeleton can be present as a single disubstituted ring, as a linker between two molecules, or embedded in a polyheterocycle. The cycloaddition reactions are usually catalysed by copper or ruthenium. Domino reactions can be achieved through dipolarophile anion formation, generally followed by cyclisation. The variety of attainable heterocyclic structures gives an ill…
Synthesis and reactivity of β-amino-α,β-unsaturated oxa- and thiazolines
1992
Abstract A simple and efficient route to masked β-amino-α,β-unsaturated acids 3 by reaction of metalated oxa- and thiazolines with nitriles has been developed. The reactivity of 3 has also been explored.