Mikhail A. Kuznetsov

Synthesis of oxazoles from α,β-unsaturated carbonyl compounds through 2-acylaziridines

Oxidative addition of N-aminophthalimide to benzylideneacetone and chalcones followed by thermolysis of the arising 2-aryl-3-acyl-1-phthalimidoaziridines led to the formation of 2,5-disubstituted oxazoles in an overall yield 30–55%. Electron-donor substituents in the aryl fragment of 2-aryl-3-aroyl-1-phthalimidoaziridines accelerate their conversion into oxazoles, and similar substituents in the aroyl fragment retard this process. The possibility was demonstrated of going over to oxazoles from α,β-unsaturated carbonyl compounds via 2-acyl-1-sulfonylaziridines employing chloramine-B. However ethyl 2 cyanocinnamate reacted with chloramine-B with the rupture of the C=C bond and the formation of N-benzylidene-benzenesulfamide.

Synthesis of 2-(Hetero)aryl-5-(trimethylsilylethynyl)oxazoles from (Hetero)arylacrylic Acids

A three-step method for the synthesis of 2-(hetero)aryl-5-(trimethylsilylethynyl)oxazoles is described. Easily accessible bis(trimethylsilyl)acetylene and acrylic acid derivatives are used as starting materials for the preparation of mono- and disubstituted 5-(trimethylsilyl)pent-1-en-4-yn-3-ones. Oxidative phthalimidoaziridination of these enynones provides the key 2-acyl-1-phthalimidoaziridines that are further utilized in the thermal expansion of the three-membered ring to furnish the target functionalizable oxazoles.

Thermal and acid-catalyzed transformations of 3H-pyrazoles obtained from diphenyldiazomethane and methyl phenylpropiolate

Reaction of diphenyldiazomethane with methyl phenylpropiolate in diethyl ether alongside the expected methyl triphenyl-3H-pyrazole-4-and-5-carboxylates (I and II) (38 and 24%) gave rise also to 8% of methyl 3,5-diphenyl-1-(1-ethoxyethyl)-1H-pyrazole-4-carboxylate. The main thermolysis product obtained from 4-methoxy-carbonyl derivative I was methyl 1,3,5-triphenyl-1H-pyrazole-4-carboxylate, whereas from regioisomer II formed predominantly methyl 4,4,5-triphenyl-4H-pyrazole-3-carboxylate and 1-methoxycarbonyl-2,3,3-triphenylcyclopropene that was a minor product of 3H-pyrazole I thermolysis. Addition of concn. H2SO4 to the solutions of methyl triphenyl-3H-pyrazole-4-and-5-carboxylates in AcOH resulted in fast regioselective isomerization of the 3H-pyrazole derivatives into the corresponding 4H-pyrazoles.

Oxidation ofN-Aminophthalimide in the Presence of Conjugated Azoalkenes: Azimines, Azoaziridines, and [1,2,3]Triazoles

The oxidation of N-aminophthalimide (1) with lead tetraacetate in the presence of the phenylazoalkenes 2 afforded 2-phenylazo-1-(N-phthalimido)aziridines 3 or 2-phenyl[1,2,3]triazoles 7, as well as phthalimide (4). The reaction of 2-phenylazo-1-propene (2d) produced 5-methyl-2-phenyl[1,2,3]triazole (7d) and N-[2-(phenylhydrazono)propylideneamino]phthalimide (8d). The cyclic azoalkene 3,3,5-trimethyl-3H-pyrazole (11) gave a mixture of (Z)-3,3,5-trimethyl-1-[N-(phthalimido)amino]-3H-pyrazol-1-ium-2N-ide [(Z)-12] together with the regioisomers (E)- and (Z)-3,3,5-trimethyl-1-[N-(phthalimido)amino]-3H-pyrazol-2-ium-1N-ides [(E)- and (Z)-13].

Thermolysis of dimethyl cis- and trans-1 pthalimidoaziridine-2,3-dicarboxylates in the presence of dipolarophiles

Thermolysis of dimethyl esters of stereoisomeric phthalimidoaziridine-2,3-dicarboxylic acids in the presence of dimethyl fumarate, dimethyl maleate, and N-phenylmaleimide occurred stereo-specifically and stereoselectively led to the formation of derivatives of 1-phthalimidopyrrolidine, products of 1,3-dipolar additrion of intermediately arising azomethine ylides. In keeping with the rules of the conservation of orbital symmetry the thermal opening of the 2,3-disubstituted 1-phthalimidoaziridines into azomethine ylides occurred conrotatory. The relative positions of the substituents in the dipolarophiles is retained in the reaction products indicating the concerted addition mechanism.

Organic chemistry. History and mutual relations of universities of Russia

The review describes the history of development of organic chemistry in higher schools of Russia over a period of 170 years, since the emergence of organic chemistry in our country till now.

Thermolysis of 1-Phthalimidoaziridine-2-carbonitriles in the Presence of Dipolarophiles

Thermolysis of trans-3-phenyl-1-phthalimidoaziridine-2-carbonitrile and trans-1-phthalimidoaziridine-2,3-dicarbonitrile in the presence of several dipolarophiles involves 1,3-dipolar cycloaddition to intermediate azomethine ylides and leads to 1-phthalimidopyrrolidine derivatives with good yields and high stereoselectivity. Thermally induced opening of the three-membered ring in trans-2,3-disubstituted 1-phthalimidoaziridines occurs in conrotatory mode to produce the corresponding cis-azomethine ylides in keeping with the orbital symmetry conservation rules. The relative configuration of substituents in the dipolarophiles is retained, which implies concerted mechanism of the addition.

Oxidative addition of N-aminophthalimide to 2-alkenyl-1,3,4-oxadiazoles. Synthesis of aziridinyloxadiazoles

Oxidation of N-aminophthalimide with lead tetraacetate in the presence of 2-[(E)-2-arylethenyl]-5-phenyl-1,3,4-oxadiazoles gives the corresponding 2-(3-aryl-1-phthalimidoaziridin-2-yl)-5-phenyl-1,3,4-oxadiazoles. From 2-phenyl-5-[(1E,3E)-4-phenylbuta-1,3-dien-1-yl]-1,3,4-oxadiazole only the addition product at both C=C bonds was obtained, while in the reaction with 2,5-bis[(E)-2-phenylethenyl]-1,3,4-oxadiazole both mono- and bis-adducts were isolated.

Alkylation and Aminomethylation of 1,3-Dihydro-2Н-Benzimidazole-2-Thione

Alkylation of 1,3-dihydro-2Н-benzimidazole-2-thione (2-mercaptobenzimidazole) with bromoethane and chloroacetic acid derivatives occurrs at the sulfur atom, leading to the corresponding 2-sulfanylbenz-imidazole derivatives. Aminomethylation of 1,3-dihydro-2Н-benzimidazole-2-thione with piperidine and 4-methylpiperidine gives reaction products at both nitrogen atoms, while reaction with morpholine gives derivative at only one nitrogen atom, which is in an equilibrium with the starting compound and bis-adduct in DMSO solution.

Photoelectron spectra and electronic structures of 2-alkoxy-1-tert-alkyldiazen-1-oxides and 1-alkoxy-3,3-dialkyltriazen-2-oxides

Abstract The electronic structures of 2-alkoxy-1- tert -alkyldiazen-1-oxides ( 1b—e ) and 1-alkoxy-3,3-di- alkyltriazen-2-oxides ( 2a—c ) have been studied by photoelectron spectroscopy and semiempirical quantum chemical calculations. It was shown that n-π conjugation in such “π-electron overcrowded” compounds is rather uneffective. As a result, the presence of the alkoxy groups in 1 and the dialkylamino groups in the cross-conjugated system 2 lead only to minor perturbations of the n- and π-type orbitals of the diazenoxide moiety. The HOMOs of 1 and 2 are π-type orbitals localized essentially on the atoms of the diazenoxide fragment. The second (in 1 ) or third (in 2 ) highest occupied MOs are n-type orbitals localized on the oxide oxygen atom.