Announcement about the defense of Pulatova Zulhumor's Doctor of Philosophy (PhD) dissertation

Announcement about the defense of Pulatova Zulhumor's Doctor of Philosophy (PhD) dissertation

I. General information.

Dissertation topic, specialization code (name of the field of study for which the degree is awarded): “Synthesis and chemical modifications of 6-H(substituted)-benzoxazolin-2-ones (thiones)”, 02.00.03 – Organic chemistry (chemical sciences).

Dissertation topic registered number: B2023.2.PhD/K621

Supervisor: Elmuradov Burkhon Zhurayevich

Dissertation prepared institution: Acad. S. Yunusov Institute of the Chemistry of Plant Substances, AS RUz.

Institution where Scientific Council operates, Scientific Council number: Acad. S. Yunusov Institute of the Chemistry of Plant Substances. AS RUz, DSc. 02/30.01.2020.K/T.104.01.

Opponents: doctor of chemical sciences, Khodzhaniyazov Khamid Utkirovich, doctor of chemical sciences, Kholikov Tursinali Suyunovich.

Lead organization: Tashkent Pharmaceutical Institute.

Dissertation direction: theoretical and practical.

II. The aim of the study is the synthesis of benzoxazoline-2-one, 6-chloro-benzoxazoline-2-one, benzoxazoline-2-thione, 2-hydrazinylbenzoxazoles, electrophilic and nucleophilic substitution/addition reactions, determination of the main factors influencing the course and direction of reactions, determination of the structure, physicochemical and biological properties of the synthesized compounds.

III. Scientific novelty of the study is as follows:

as a result of reactions of substituted aminophenols and aromatic aldehydes in neutral (ethanol) and acidic (glacial AcOH) conditions, it was established that instead of the formation of cyclization products (2-substituted benzoxazoles), products of nucleophilic addition-elimination of the amino group with the carbonyl group (Schiff bases) are formed; with an increase in the concentration of acid and temperature (17.5 equivalents, 118°C), the corresponding acetamide (75%) is released;

as a result of alkylation (propargylation) reactions of benzoxazoline-2-one, benzoxazoline-2-thione and 6-chlorobenzoxazoline-2-one with propargyl bromide, selective N-, S-propargyl derivatives were obtained in good yields;

for the first time the formation of “methylene/thiomethylene-bridged” hybrid benzoxazole-triazole molecules was discovered using 1,3-bipolar cycloaddition reactions in the presence of N-,S-propargyl derivatives and aromatic azides in the presence of a Cu⁺ catalyst, and the most optimal reaction conditions were recommended (toluene, 110°C, Cu₂I₂, 5-6 hours);

when carrying out azide-alkyne cycloaddition reactions without a catalyst, a mixture of 1,4- and 1,5-isomers of 1,2,3-triazole derivatives is formed, and in the presence of a copper(I) halide catalyst, selective formation of 1,4-isomers is observed, and a series of catalyst activities Cu₂Cl₂<Cu₂Br₂<Cu₂I₂ is determined;

a reaction of benzoxazoline-2-thione with acrylonitrile was carried out under “green chemistry” conditions (H₂O, 50-60°C, 6 hours) and a modification of the “genetic series” (nitrile → carboxylic acid → ester → hydrazide → arylidenehydrazide) of the obtained propanenitrile was carried out, the mechanism of cyanoethylation was established and the obtained products were recommended for use in modern organic synthesis;

as a result of the condensation reaction of 2-hydrazinylbenzoxazole containing a bifunctional fragment with aromatic aldehydes containing various substituents, it was established that hydrazones of the E-isomeric form are formed in good and high yields;

as a result of the selective reaction of 2-hydrazinylbenzoxazole with carbonyl compounds (aromatic acid chlorides, ketones, sulfochlorides) at the hydrazinyl fragment, new diaroyl, arylidenehydrazinyl derivatives and sulfonohydrazides were obtained;

as a result of catalytic arylsulfonylation and aroylation of benzoxazoline-2-one at the endocyclic N-atom, amides and sulfonamides are formed in medium and high yields.

IV. Implementation of research results.

Based on the obtained scientific results on obtaining products of electrophilic and nucleophilic substitution/addition of benzoxazoline-2-one, benzoxazoline-2-thione, 6-chlorobenzoxazolin-2-one, 2-hydrazinylbenzoxazole and determining the structure and biological properties of the synthesized compounds:

X-ray diffraction results of 3-(4-methylbenzoyl)benzo[d]oxazol-2(3H)-one and 3-tosylsulfonylbenzo[d]oxazol-2(3H)-one are included into Cambridge Crystallographic Database (The Cambridge Structural Database, https://www.ccdc.cam, CCDC: 2294649, 2294650). The results of including new compounds into the database made it possible to synthesize similar compounds and describe their structure;

the results of the synthesis and chemical modification of benzoxazoles and their derivatives were used in the fundamental project № F-FA-2021-408 "Study of the patterns of introducing pharmacophoric fragments into a molecule based on modern cross-coupling and heterocyclization reactions" (Certificate 4/1255-1150 of the Academy of Sciences of the Republic of Uzbekistan dated May 28, 2024). As a result, it was established that Schiff bases and amides are important raw materials in the synthesis of benzoxazoles and can be successfully used in the preparation of new derivatives of 1H-1,2,3-triazoles in 1,3-bipolar cycloaddition reactions of propargyl ethers and aromatic azides.

 

Chairman of the Scientific Council:                                        Sagdullayev Sh.Sh.

Scientific Secretary of the  Scientific Council:                         Khidirova N.K.

Supervisor:                                                                            Elmuradov B.Zh.

Candidate:                                                                              Pulatova Z.J.

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