An enantioselective (52-98% ee) Michael addition between cyclic β-diones and α,β-unsaturated enones was established in the presence of quinine-based primary amine or squaramide. A variety of cinnamones were smoothly converted into the desired 3,4-dihydropyrans in moderate to high yields (63-99%). Chalcones were also suitable acceptors and gave rise to the expected adducts in satisfactory yields...

Mariannaeapyrone ((E)-2-(1,3,5,7-tetramethyl-5-nonenyl)-3,5-dimethyl-6-hydroxy-4H-pyran-4-one) is a new fungal metabolite isolated from fermentations of the common mycophilic deuteromycete Mariannaea elegans. The chemical structure of the 4-pyrone was determined by spectroscopic techniques. Mariannaeapyrone is a selective inhibitor of the thromboxane A2 induced aggregation of human platelets, w...

In the xanthene ring system of the title compound, C(23)H(25)BrO(4), the 4H-pyran ring is almost planar [maximum deviation = 0.040 (3) Å] and the cyclo-hexene ring adopts a sofa conformation. The cyclo-hexene ring attached to the xanthene system is puckered [Q(T) = 0.427 (3) Å, θ = 55.0 (4) ° and ϕ = 164.4 (6) °]. In the crystal, mol-ecules are linked to each other by O-H⋯O and C-H⋯O hydrogen b...

Due to the antitumor activity of Gallium MAL complex, as well as recent findings on new targeted biomolecules in malignant cells through this complex, the development of radiolabeled gallium complex for future imaging studies was targeted. Ga-67 labeled 3-hydroxy-2-methyl-4H-pyran-4-onate (Ga-67 MAL) was prepared using freshly prepared Ga-67 chloride and 3-hydroxy-2-methyl-4H-pyran-4-onate in a...

Infections are one of the most important causes of death, disability and inappropriate conditions for millions of people around the world. Therefore, the development in prognosis, prevention and treatment of infectious diseases made a considerable progress in designing and synthesis of new antimicrobial drugs. Nowadays, due to the increase in microbial resistance, discovery of new compounds wit...

The reactions of 2-perfluoroacyl-1H-benzo[f]chromenes and 6,7-dimethyl-3-trifluoroacetyl-4H-chromene with primary aliphatic amines ammonia afforded a series enamino ketones containing (2-hydroxynaphthalen-1-yl)methyl or 2-hydroxybenzyl substituent in the ?-position respect to carbonyl group. These involved opening pyran ring, which followed aza-Michael addition as initial step. obtained were fo...

Abstract Background : It is a practice to use traditional medicine for curing various illnesses in West Africa. Acacia hebecladoides , albida and Gmelina arborea were selected based on their belief treating ailments such as: hallucinations, inflammation tuberculosis. The study sought validate the antitubercular activity, antioxidant properties phytochemical components of extracts fractions leav...

Introduction: Due to the cell labeling potentials of various metal-maltol complexes, the idea of developing a possible cell labeling imaging agent using single photon emission computed chromatography (SPECT) with [In]-maltolate complex has been investigated. Methods: [In] labeled 3-hydroxy-2-methyl-4H-pyran-4-onate ([In]-maltolate) was prepared using freshly prepared [In]InCl3 and 3-hydroxy-2-m...

New macrocyclic polyether-diester ligands (3-5) containing the 4H-pyran-4-one subcyclic unit have been prepared by treating various glycols with dimethyl chelidonate (10). In the reaction of compound 10 with ethylene glycol and diethylene glycol, two noncyclic diester and tetraester (6-9) were produced in each case. The new marcocyclic ligand 4 formed stable complexes with benzylammonium pe...