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2,2-Dimethyl-1,3-dioxane-4,6-dione (Meldrum acid, isopropylidenmalonate) is widely used by synthetic chemists due to its structural features. The dual nature of the reactivity of Meldrum acid (both electrophilic and/or nucleophilic reagent) determines the synthetic value in the construction of new heterocyclic systems with practically signifi cant properties. A wide range of biological activity has been revealed in a number of compounds containing a 2,2-dimethyl-1,3-dioxane-4,6-dione fragment in their structure.

The role of spatial and electronic  structure, hydrophobic  properties and concentration of organoselenium compounds  on their interaction with fungal metabolites  - carbohydrate-binding proteins, extracellular lectins  of Lentinula edodes (shiitake mushroom) has  been consi­ dered. By  the hybrid density  functional theory  method at the B3LYP/6-31G(d,p) theory  level, spatial and electronic  structure of the 1,5-di(4-R-phenyl)-3-selenopentanediones-1,5 molecules  has  been studied.

The reaction of 1,3-dipolar cycloaddition azomethine ylides obtained by the in situ interaction of 11H-indeno[1,2-b]quinoxalin-11-one and proline, and 3-phenyl-1-pyrrolyl-2-en-1-ones has been used for the synthesis of substituted spiropyrrolizidines in continuation of the study the use of new enones as dipolarophiles. The conditions for the implementation of a three-component synthesis (temperature regime, solvent, activation method) are selected. The best performance has been obtained by refl uxing the reaction mixture in ethanol.

This work demonstrates the possibility of obtaining new biologically active molecules containing a privileged imidazolone fragment by the Brønsted acid-catalyzed reaction of 1,3-dimethylurea with 1-(2-oxo-2-phenylethylidene)pyrrolo[3,2,1-ij]quinolin-2-ones. The presence of an active oxoylidene system in ones makes it possible to introduce these compounds into cyclization reactions with various binucleophilic agents.

Reactions of 4-oxobutanoic acids as well as their cyclic analogues 3H-furan-2-ones with 1,3-binucleophilic reagent (2-aminophenyl) methanol lead to the formation of 1-R-5H-benzo[d]pyrrolo[2,1-b][1,3]oxazines and 3a-R-2,3,3a-trihydro-5H-benzo[d]pyrrolo[2,1-b][1,3]oxazin1-ones, respectively. Quantum-chemical calculations of the Fukui reactivity indices and local hardness have substantiated the mechanisms of the reactions carried out.

Впервые выявлена интенсивно красная пигментация мицелия,
обусловленная накоплением элементного селена в резуль-
тате трансформации селенорганического соединения выс-
шим грибом Lentinula edodes (шиитаке). Исследовано влияние
1,5-дифенил-3-селенпентандиона-1,5 (диацетофенонилселенид,
препарат ДАФС-25) на рост съедобного гриба Lentinula edodes
в условиях жидкофазного и твердофазного культивирования.
Обнаруженное явление стимуляции роста мицелия предположи-
тельно связано с антиоксидантными свойствами селена, благо-

The reaction of 1,3-dipolar cycloaddition of conjugated aryl(hetaryl) methylideneacetones, which containing various peripheral substituents, with azomethine ylides was carried out. It was established that the interaction is not chemoselective and proceeds with the participation of two non-equivalent reaction centers of dipolarophile with high diastereoselectivity. The products of cycloaddition were a mixture of structural isomers endo-cycloaddition. Monoenone transform to spyropyrrolidines with high endo-stereoselectivity.

Aryl-substituted triazolohexahydroquinazolines have been synthesized by means of three-component condensation of pnitro(pbromo) benzaldehydes, cyclohexanone, 1,2,4-triazol-3-amine. A scheme of the reaction mechanism is proposed, which makes it possible to explain the features of the behavior of p-nitro(bromo) benzaldehydes in condensation reactions in comparison with their ortho-substituted analogs.