Synthesis of new functionalized 5,5-dimethyl-1-pyrroline 1-oxides and their investigation as spin traps

The reactions of 5,5-dimethyl-3-oxo-1-pyrroline 1-oxide (3-oxo-DMPO, 1) with NH₂OH and N₂H₄ afforded oxime (2a) and hydrazone (2b), respectively. The reaction products were studied as spin traps for the short-lived radicals HO^·, Ph^·, PhCO₂ ^·, NC(Me₂)C^·, and NC(Me₂)CO^·. The nitroxides generated in the reactions of the above-mentioned short-lived radicals with nitrones 1 and 2a,b were characterized by ESR spectroscopy. Of these nitrones, oxime 2a is the most effective radical trap.     

Synthesis and Cytotoxic Activity of 4-Substituted 3-Cyano-6,6-dimethyl-5,6-dihydro-2-pyranones

The respective 4-(arylvinyl)lactones and compounds of the Michael adduct type were synthesized by the condensation of substituted benzaldehydes with 3-cyano-4,6,6-trimethyl-5,6-dihydro-2-pyranone in the presence of catalytic amounts of sodium hydroxide. It was shown by the semiempirical AM1 method that the indicated products can be formed through one and the same intermediate compound. Some of the synthesized phenylvinyl-5,6-dihydro-2-pyranones have a cytotoxic effect, and this corresponds to the prognosis of the OREX expert system.     

Reaction of 2-substituted 5,5-dimethyl-4-oxo-1-pyrroline-1-oxides with electrophilic reagents

The reaction of -oxonitrones, derivatives of pyrroline, with electrophilic reagents can proceed either at the oxygen atom of the nitrone group in the composition of the heterocyclic ring, or at the carbon atom between the carbonyl and nitrone group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 395–400, February, 1990.     

Synthesis of 1,2-benzisothiazolin-3-ones by ring transformation of 1,3-benzoxathiin-4-one 1-oxides

1,2-Benzisothiazolin-3-ones were synthesized from 1,3-benzoxathiin-4-one 1-oxides by means of a nonhazardous and inexpensive method. The 1,3-benzoxathiin-4-one 1-oxides were prepared by oxidation of 1,3-benzoxathiin-4-ones with hydrogen peroxide in the presence of a catalyst. Attack of amines on the carbonyl groups of the 1,3-benzoxathiin-4-one 1-oxides and subsequent elimination of carbonyl compounds likely produced sulfenic acids, which then underwent ring closure to afford the 1,2-benzisothiazolin-3-ones.     

Synthesis of 3-substituted 4-imino-4,5-dihydro-1,2,3-triazole 1-oxides and 4-amino-1,2,3-triazole 1-oxides. Crystal and molecular structure of 4-imino-5,5-dimethyl-3-phenyl-4,5-dihydro-1,2,3-triazole 1-oxide

A new procedure for the synthesis of triazole N-oxides, based on base-induced intramolecular cyclization of 1-(-cyanoalkyl)-3-aryl(hetaryl)triazen-1-oxides, is proposed. An X-ray study of 4-imino-5,5-dimethyl-3-phenyl-4,5-dihydro-1,2,3-triazole 1-oxide was carried out.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 746–751, April, 1993.     

Synthesis with 1,2-Oxazines. II. Synthesis and Properties of 2,3-dimethyl-5,6-dihydro-4H-1,2-oxaziniumiodide

Preparation of 2,3-Dimethyl-5,6-dihydro-4H-1,2-oxaziniumiodide was achieved by N-alkylation of 3-methyl-5,6-dihydro-4H-1,2-oxazine. Reactions with C-nucleophiles led to the corresponding N-methyl-perhydro-1,2-oxazine derivatives. Reaction with sodium hydride in triglyme led to 3-methyl-4-aza-1,3-pentadiene.     

3-Aryl-5,5-dimethyl-5,6-dihydro-1,2,4-triazolo[3,4-a]isoquinolines: A new example of atropo isomerism

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1001–1002, July, 1992.     

A new ring transformation of 3-halo-2-azidopyridine 1-oxides. A novel synthesis of 1,2-oxazin-6-ones

The course of the thermal ring-opening and recyclization of 2-azidopyridine 1-oxides is radically altered by the presence of a 3-halo substituent. Provided the 6-position is blocked, recyclization leads to a 6-cyano-6-halo-1,2-oxazine which hydrolyzes very readily to the 6H-1,2-oxazin-6-one. The structure of 4-bromo-3-methyl-6H-1,2-oxazin-6-one so obtained was confirmed by single crystal X-ray analysis. If the 6-position is not blocked, the product undergoes a further ring opening to give (Z)-β-cyanoacrylates.     

Synthesis of some 3-alkenyl-4-oxo-1-phenyl-5,6-dihydro-1H,4H, -pyrano[2,3-C]pyrazole derivatives

The title compounds were prepared from 3-alkenyl-1-phenyl-2-pyrazolin-5-one derivatives and α,β-unsaturated acyl chlorides as potential cardiotonic agents.     

Synthesis of substituted 2-amino-5,6-dihydro-4h-1, 3-oxazines

4,4,6-Trimethyl-2-alkyl(aryl)amino-5,6-dihydro-4H-1,3-oxazines were synthesized via two methods: amination of 4,4,6-trimetiiyl-2-methylthio-5,6-dihydro-4H-1,3-oxazine and cyclization of N-aryl-N-(2-methyl-4-hydroxy-2-amyl)-S-methylisothiourea.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1037–1040, August, 1972.     

Wolff-kishner reduction of 5-methyl- and 6,6-dimethyl-5-hydroxy-4-oxo-3-phenylpyrrolidino-[1,2-b]pyrazoles

The reduction of 5-hydroxy-5-methyl-4-oxo-3-phenylpyrrolidino[1,2-b]pyrazole by heating with hydrazine hydrate in alkaline solution is accompanied by fission of the bicyclic skeleton or by dehydration depending on the solvent and reaction temperature. A two-stage synthesis of 6,6-dimethyl-3-phenyl-pyrrolidino[1,2-b]pyrazole from 5-hydroxy-6,6-dimethyl-4-oxo-3-phenylpyrrolidino[1,2-b]pyrazole is proposed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1345–1348, October, 1993.     

A convenient synthesis of N-aryl-1,2-dihydro-2-oxo-3-pyridinecarbox-amides,N-aryl-N-methyl-1,2-dihydro-2-oxo-3-pyridinecarboxamides and their 1-methyl (O-methyl)-derivatives

A new and versatile method for the preparation of the isonixine analogues, N-aryl-1,2-dihydro-2-oxo-3-pyridinecarboxamides and N-aryl-N-methyl-1,2-dihydro-2-oxo-3-pyridinecarboxamides is described via the selective chlorination of 2-hydroxynicotinic acid. In order to prepare these new compounds, the chemistry of the methyl-blocked forms of each tautomer is discussed.     

Synthesis and reactions of 1-(4-bromo-, 4-fluoro-, and 4-trifluoromethylphenyl)-6,6-dimethyl-4-oxo-4,5,6,7-tetrahydroindazoles

From 2-formyldimedone and 4-bromo-, 4-fluoro-, and 4-trifluoromethylphenylhydrazines we have obtained the corresponding 2-arylhydrazinomethylenedimedones, which in acid medium undergo ring closure to form 1-substituted 6,6-dimethyl-4-oxo-4,5,6,7-tetrahydroindazoles. Oxidation of the latter by selenous acid leads to the corresponding 4,5-dioxo-4,5,6,7-tetrahydroindazoles, which then were converted to derivatives of 4,5-dihydro-3H-pyrazolo[4,3-a]phenazine and 4,5-dihydro-1H(3H)-indazolo[4,5-d]imidazole.Riga Technical University, Riga LV-1658. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1669–1675, December, 1997.     

Synthesis and Photoisomerization of 3-Cyano-6,6-dimethyl-4-(4-nitrophenylvinyl)-5,6-dihydropyran-2-one

The condensation of 4-nitrobenzaldehyde with 3-cyano-4,6,6-trimethyl-5,6-dihydropyran-2-one leads to the formation of a crotonization product and a compound of the Michael adduct type. The main product of the photochemical conversion of (E)-3-cyano-6,6-dimethyl-4-(4-nitrophenylvinyl)-5,6-dihydropyran-2-one is the Z-isomer. Investigation of the photoisomerization of 3-cyano-6,6-dimethyl-4-(4-nitrophenylvinyl)-5,6-dihydropyran-2-one by the semiempirical AM1 method showed that in the ground state the E-isomer was thermodynamically more stable than the E-isomer. E-Z-photoisomerization is effected most probably through the lowest excited singlet state S₁.     

Reaction of 2-substituted 5,5-dimethyl-4-oxo-1-pyrroline-1-oxides with nucleophilic reagents and synthesis of nitroxyl radicals—derivatives of pyrrolidine

The reaction of -oxonitrones, derivatives of pyrroline, with nitrogeneous nucleophiles and NaBH₄ proceeds at the carbonyl group with the retention of the nitrone group. The reaction with organomagnesium and organolithium compounds takes place at the nitrone group with the retention of the carbonyl group, while the oxidation of the products formed proceeds to form nitroxyl radicals—Derivatives of pyrrolidin-4-one, which were used in the synthesis of spin-labeled dioximes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 390–395, February, 1990.     

Synthesis of 3-carboethoxy-4,11-dihydro-11-alkyl/phenyl-4-oxopyrimido[1,2-b][1,2,4]benzothiadiazine 6,6-dioxides. A novel heterocyclic ring system

The synthesis of some novel 3-carboethoxy-4,11-dihydro-11-alkyl/phenyl-4-oxopyrimido[1,2-b][1,2,4]benzo-thiadiazine 6,6-dioxides ( IVa-c ) from 3-amino-4-alkyl/phenyl-4H-1,2,4-benzothiadiazine 1,1-dioxides ( 1a-c ) and diethyl ethoxymethylenemalonate ( II ) is described. The compounds have been screened for their antibacterial activity.     

Synthesis of 2-(p-Toluenesulfonamido)-4-phenyl-4, 5-dihydro-1H-1, 3, 4-diazaphosphole 4-oxides

Some novel unsaturated five-membered organophosphorus heterocyclic compounds, 2-(p-toluenesulfonamido)-4-phenyl-4, 5-dihydro-1H-1, 3, 4-diazaphosphole 4-oxides 8 have been synthesized by Mannich-type reaction of p-toluenesulfonylguanidine with phenyldichlorophosphine and ketones.     

13C NMR Spectra of cyclic nitrones. 1. 2-substituted 4-methyl- and 4-phenyl-1-hydroxy-5,5-dimethyl-3-imidazoline 3-oxides

The introduction of an N-oxide oxygen atom into azomethines leads to an upfield shift of the signals for the carbon atom of the G=N group in the ¹³C NMR spectra by 30–33 ppm. This is consistent with the increase in the electron density on this atom. The signal of the nitrone carbon atom is observed in the region of 140–147 ppm, depending on the nature of the substituent at the C(₂) atom of the 3-imidazoline 3-oxide ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 247–251, February, 1985.