Search results for "Oxazole"
showing 10 items of 227 documents
Base-catalyzed isomerization of 2-isoxazolines enables a two-step enantioselective synthesis of β-hydroxynitriles from enals.
2010
The asymmetric synthesis of β-hydroxynitriles remains a challenge in organic synthesis. Herein we report a convenient synthesis of β-hydroxynitriles from enantiomerically enriched 3-unsubstituted 2-isoxazolines via a base-catalyzed ring-opening reaction that takes place without loss of enantiopurity. In combination with organocatalytic enantioselective synthesis of 3-unsubstituted 2-isoxazolines, the ring-opening enables a short 2-step synthesis of β-hydroxynitriles from α,β-unsaturated aldehydes in high enantiomeric purity.
Recurrence of the oxazole motif in tubulin colchicine site inhibitors with anti-tumor activity
2021
Abstract Because of its wide spectrum of targets and biological activities, the oxazole ring is a valuable heterocyclic scaffold in the design of new therapeutic agents with anticancer, antiviral, antibacterial, anti-inflammatory, neuroprotective, antidiabetic and antidepressant properties. The presence of two heteroatoms, oxygen and nitrogen, offers possible interactions (hydrogen, hydrophobic, van der Waals or dipoles bonds) with a broad range of receptors and enzymes. Furthermore, the oxazole core conjugates low cytotoxicity with improved compound solubility and is well suited to structural modifications such as substitution with different groups and condensation to aromatic, heteroaroma…
Novel Terphenyls and 3,5-Diaryl Isoxazole Derivatives Endowed with Growth Supporting and Antiapoptotic Properties
2008
A new study on terphenyl and diaryl-isoxazole and -isoxazoline derivatives, maintaining a common 3-adamantyl-4-hydroxyphenyl moiety, has been conducted to find compounds with growth supporting and antiapoptotic properties. Unexpectedly, diphenyisoxazole derivatives bearing a nitro group replacing the carboxylic function have been found with the highest cell protective activity within the series, in complete and in serum-free conditions. Inhibition of apoptosis induced by daunorubicin has also been observed for the most active compound.
Polymorphic and solvate structures of ethyl ester and carboxylic acid derivatives of WIN 61893 analogue and their stability in solution
2014
3-Ethyl ester- (1) and 3-carboxylic acid-isoxazole (2) derivatives of an antiviral drug analogue WIN 61893 were synthesized and characterized by X-ray crystallography and NMR spectroscopy. Crystallization experiments afforded two polymorphic structures for the ethyl ester derivative and two solvate structures for the carboxylic acid derivative based on their ability to form intermolecular hydrogen bonding interactions with the solvent molecules. The conformations of the derivatives depended greatly on the orientation of the planar isoxazole and phenyl-oxadiazole ring systems with respect to one another and were found to take up perpendicular, linear or tilted conformations. The carboxylic a…
Collapse of Cylindrical Brushes with 2-Isopropyloxazoline Side Chains Close to the Phase Boundary
2013
A high-molar-mass cylindrical brush polymer with a main chain degree of polymerization of Pw = 1047 is synthesized by free-radical polymerization of a poly-2-isopropyloxazoline macromonomer with Pn = 28. The polymerization is conducted above the lower phase transition temperature of the macromonomer, i.e., in the phase-separated regime, which provides a sufficiently concentrated macromonomer phase mandatory to obtain high-molar-mass cylindrical brushes. Upon heating to the phase transition temperature, the hydrodynamic radius is observed to shrink from 34 to 27 nm. Further increase in temperature resulted in aggregated chains which were observed to coexist with single chains until eventuall…
Enzyme molecular mechanism as a starting point to design new inhibitors: a theoretical study of O-GlcNAcase.
2011
O-Glycoprotein 2-acetamino-2-deoxy-β-d-glucopyranosidase (O-GlcNAcase) hydrolyzes O-linked 2-acetamido-2-deoxy-β-d-glucopyranoside (O-GlcNAc) residues from post-translationally modified serine/threonine residues of nucleocytoplasmic protein. The chemical process involves substrate-assisted catalysis, where two aspartate residues have been identified as the two key catalytic residues of O-GlcNAcase. In this report, the first step of the catalytic mechanism used by O-GlcNAcase involving substrate-assisted catalysis has been studied using a hybrid quantum mechanical/molecular mechanical (QM/MM) Molecular Dynamics (MD) calculations. The free energy profile shows that the formation of the oxazol…
New syntheses of condensed heterocycles from isoxazole derivatives. V. Pyrrolo[3,4-b]pyridin-4-ones
1977
Hydrogenolysis with Raney-Nickel or iron powder in acetic acid of 2,5-diphenyl-4-nitro-3-(3,5-R,R-4-isoxazolyl)pyrrolyl ketones, prepared by the Grignard reaction of 2,5-diphenylpyrrole and 3,5-R,R-4-isoxazolecarboxilic acid chlorides followed by nitration, afforded directly the desired 6H-pyrrolo[3,4-b ]pyridin-4-ones.
New synthesis of condensed heterocycles from isoxazole derivatives VI. 2,5-Dimethyl-3-aeetyl-7-amino-1H-pyrrolo[3,2-b] pyridine
1978
A new synthesis of pyrrolo[3,2-b] pyridine starting with pyrrole ring is described. The procedure allows the synthesis of 4-azaindoles bearing a sensitive group at C-7. The nitration of 4b with nitric acid and acetic anhydride at −15° gave 5. The hydrogenation of 5 led to simultaneous reduction of N-hydroxy and nitro groups and to hydrogenolysis of the isoxazole nucleus, affording an appropriate chain of atoms to building up the pyrrolo[3,2-b] pyridine ring.