Reactions of aziridines. Preparation and properties of 2-thiazolinium salts

Reaction of 1-substituted aziridines with thioamides in the presence of perchloric acid has provided a facile route to 2-thiazolinium salts. Thioformamide was used in this reaction to give the 2-unsubstituted 2-thiazolinium salts 3-[4-(2,6-xylyloxy)butyl]-2-thiazolinium perchlorate (11a) and 3-(2-cyelohexylbutyl)-2-thiazolinium perchlorate (IIc). A study of the rates of hydro-lytic breakdown of IIc and 3-(2-cyelohexylbutyl)-2-methyl-2-thiazolinium perchlorate (IId) showed that the 2-unsubstituted compound (IIc) was considerably less stable than the 2-methyl analog (IId) over the entire pH range. Use of 1-substituted aziridines in ring-opening reactions, previously applied only to 1-unsubstituted aziridines, has given expected products when thio-cyanate ion or thiourea was the nucleophile.     

Amidrazones. 6 . Synthesis of 1,2,4-thiadiazoles by thermolysis of N3-thiocarbamoylamidrazone ylides

Reaction of N³-unsubstituted amidrazone ylides ( 1a and 1b ) with alkyl or aryl isothiocyanates gives N³-thiocarbamoylamidrazone ylides ( 2 ). Thermolysis of 2 gives 3-alkyl(or aryl)-5-alkyl(or aryl)amino-1,2,4-thiadiazoles ( 3a-i ).     

Synthesis of novel 1-phenyl-1H-indole-2-carboxylic acids. II. Preparation of 3-dialkylamino, 3-alkylthio, 3-alkylsulfinyl,and 3-alkylsulfonyl derivatives

The synthesis of novel indole-2-carboxylic acids with amino- and sulfur-containing substituents in the indole 3-position is described. An Ullmann reaction with bromobenzene converted 1H-indoles with 3-(acetylamino)- and 3-(diethylamino)-substituents into 1-phenyl-1H-indoles. Reaction of 3-unsubstituted indoles with thionyl chloride provided indole 3-sulfinyl chlorides, which reacted with alkyl and aryl Grignard reagents to form the corresponding sulfoxides. The indole sulfoxides thus obtained were reduced to sulfides or oxidized to sulfones.     

Synthesis of 3-(N-arylcarbamoyl)chromones from 2-hydroxyarylaminoenones and isocyanates

Russian Chemical Bulletin - A new method for the synthesis of 2-unsubstituted and 2-substituted 3-(N-arylcarbamoyl)-chromones by the reaction of 3-dimethylamino-1-(2-hydroxyaryl)prop-2-en-1-ones...     

Synthesis of 3-(dibromoacetyl)tropolone and its reactions with thioureas and thioamides

3-(Dibromoacetyl)tropolone ( 3 ) was obtained in the reaction of 3-acetyltropolone with two equimolar amounts of phenyltrimethylammonium tribromide. This tropolone 3 reacted with thiourea, 1-methyl-2-thiourea, and 1-phenyl-2-thiourea to afford N-unsubstituted and N-methyl- or N-phenyl-substituted 3-(2-amino-4-thiazolyl)tropolones. The reactions of 3 with thioacetamide and thiobenzamide gave 3-(2-methyl-and 2-phenyl-4-thiazolyl)tropolones.     

A simple and convenient synthesis of 4-methyl-3-nitro-2-trihalomethyl-2H-chromenes from N-unsubstituted imines of 2-hydroxyacetophenones and trichloro(trifluoro)ethylidene nitromethanes

The reaction of N-unsubstituted imines of 2-hydroxyacetophenones with trichloro(trifluoro)ethylidene nitromethanes in the presence of DABCO proceeds via tandem oxa-Michael/aza-Henry additions (in dichloromethane) or aza-Michael addition (in benzene) to give 4-methyl-3-nitro-2-trichloro(trifluoro)methyl-2H-chromenes or 1,1,1-trichloro(trifluoro)-3-nitro-N-[1-(2-hydroxyaryl)ethylidene]propan-2-amines, respectively.     

Stereoselective Synthesis of 3-Substituted 4-(Formyloxy)-2-azetidinones by the Unusual Baeyer-Villiger Reaction of beta-Lactam Aldehydes. Scope and Synthetic Applications

The Baeyer-Villiger oxidation of 4-formyl-beta-lactams 1with m-CPBA gave 4-(formyloxy) beta-lactams 2 in a simple, efficient, and totally stereoselective process. This reaction is one of the scarce examples of the preferred migration of a carbon moiety in an aliphatic aldehyde. The influence of the substituents at N1 and C3 of the four-membered ring in the Baeyer-Villiger rearrangement has been studied. Thus, alkyl, alkenyl, aryl, and alkyloxy 3-substituted-1-(p-anisyl)-2-azetidinones 1 form exclusively 4-(formyloxy) beta-lactams 2. Amide or acetoxy substituents at C3 of the four-membered ring produce mixtures of 4-(formyloxy) beta-lactams 2and 4-carboxy beta-lactams 5. The exclusive formation of carboxy derivatives is observed sometimes for 1-alkyl-substituted-2-azetidinones 1. 4-(Formyloxy) beta-lactams 2 are suitable starting materials to prepare different 4-unsubstituted beta-lactams 9 using beta-hydroxy amides 8 as isolable intermediates. The overall transformation 4-formyl-2-azetidinone to 4-unsubstituted beta-lactam is an easy and convenient stereoselective route to these interesting types of compounds.     

Nitropyrazoles 15. Synthesis and some transformations of 1-(2,4-dinitrophenyl)-4-methyl-3,5-dinitropyrazole

The method for preparation of 1-(2,4-dinitrophenyl)-4-methyl-3,5-dinitropyrazole has been developed. Due to the larger CH-acidity of 4-Me-group compared to 1,4-dimethyl-3,5-dinitropyrazole, 1-(2,4-dinitrophenyl)-4-methyl-3,5-dinitropyrazole is capable of reacting with substituted benzaldehydes to afford 4-[(E)-2-arylvinyl]-1-(2,4-dinitrophenyl)-3,5-dinitropyrazoles. Under the action of nucleophiles, dinitrophenyl group is detached from the former compounds leading to previously unknown N-unsubstituted 4-[(E)-2-arylvinyl]-3,5-dinitropyrazoles.     

2-Benzopyrylium salts. 27. Some transformations of 6-oxodibenzo[a,g]-quinolizinium salts

The synthesis of 6-oxodibenzo[a,g]quinolizinium perchlorate — an analog of the alkaloid berberine — and a number of its derivatives, including mesoionic compounds, was accomplished on the basis of a 1-unsubstituted 3-(2-methylenecarboxyaryl)-2-benzopyrylium salt. The interconversions of the compounds obtained in this research were studied.See [1] for communication 26.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1381–1387, October, 1982.     

Ketalizations of aryl ω-(2-imidazolyl)alkyl ketones by glycerol and 3-mercapto-1,2-propanediol. synthesis and characterization of cis- and trans-{2-aryl-2-[ω-(2-imidazolyl)alkyl](1,3-dioxolan-4-yl and 1,3-oxathiolan-5-yl)}methanols

Aryl 2-[(2-imidazolyl)ethyl or 3-(2-imidazolyl)propyl]ketones were ketalized by glycerol or 3-mercapto-1,2-propanediol in boiling benzene in the presence of 4-toluenesulfonic acid to provide the title compounds. The aryl substituents are 4-chloro-, 4-bromo-, 4-fluoro-, or 2,4-dichlorophenyl. While aryl (2-imidazolyl)methyl ketones condensed with glycerol to form cis- and trans-{2-aryl-2-[(2-imidazolyl)methyl]-4-(hydroxymethyl)}-1,3-dioxolanes, related condensations with 3-mercapto-1,2-propanediol, under similar, or even more stringent reaction conditions, produced no 1,3-oxathiolane analogs, with the starting ketones being recovered. Separation and structure determination of these racemic cis and trans isomeric products are described. The structure of these stereoisomers was established by means of ¹H and ¹³C nmr correlation and nOe experiments. Selective methylation of the N-unsubstituted 2-imidazolyl alcohols with one equivalent sodium hydride and methyl iodide provided the corresponding N-methyl alcohols in excellent yields. With excess benzoyl chloride, N-unsubstituted 2-imidazolyl alcohols were initially converted to O, N-dibenzoates from which the N-benzoyl group was easily cleaved by ammonium hydroxide in ethanol to provide benzoate esters.     

Heterocyclen aus α-nitroolefinen. XII . 3-Acetyl-4,5-dihydro-5-(methylenamino)furane und 3-acylpyrrole aus α-nitroolefinen und β-diketonen

From α-nitroolefines 1 and β-diketones 2 3-acetyl4,5-dihydro-5-(methy1eneamino)furans 5 are prepared. Furans 5 react in acid medium to yield 1-unsubstituted 3-acylpyrroles 6 , catalytic hydrogenation yields 1-substituted 3-acylpyrroles 9 . The ¹H-nmr and ¹³C-nmr investigations prove the constitutions.     

The chemistry of 2H-3,1-benzoxazine-2,4(1H)dione (isatoic anhydrides) 1. The synthesis of N-substituted 2H-3,1-benzoxazine-2,4(1H)diones

Three methods for the preparation of N-substituted 2H-3,1-benzoxazine-2,4(1H)diones (isatoic anhydrides) (1) utilizing 2-chloro-, 2-nitrobenzoic acids and N-unsubstituted isatoic anhydrides as starting materials, are described.     

Nitrogen bridgehead compounds,part 68. Studies on quinolizine derivatives. Part 2. Synthesis of 1,3-disubstituted-4H-quinolizine derivatives

Quinolizine compounds 1 and 2 or their monocyclic tautomers 3 and 4 have been synthesized using 2-pyri-dineacetic acid derivatives 6a, b, A, B and ethoxymethylenemalonic acid derivatives 7a, b, c in base catalyzed or thermic reaction. In the 6-unsubstituted series, both the 4-oxo and 4-imino derivatives could have been obtained, in the 6-substituted series, however the 4-oxo ones only, whereas instead of the 4-imino derivatives, their monocyclic tautomers 3, 4 have been isolated. In the 6-unsubstituted series, the primarily formed 4-imino compounds have been rearranged into 4-oxo ones under stronger conditions. The structure of the isolated compounds have been proved by ultraviolet, infrared and ¹H nmr spectra, that of 3B=C by X-ray analysis as well.     

Stable nitroxide radicals. Reaction between 2-cyano- and 4-cyanobenzoquinoline N-oxides and the grignard reagent

2,2-Diphenylbenzoquinolinenitroxide radicals were obtained starting from 2-phenyl-, 2-cyano, 4-cyano-benzoquinoline N-oxides, or from unsubstituted benzoquinoline N-oxides with phenylmagnesium bromide. The elimination of bromomagnesium hydride from the 2-unsubstituted benzoquinoline N-oxides and cyanomagnesium bromide from the 2- or 4-cyanobenzoquinoline N-oxides is discussed.     

Nonconcerted cycloaddition of 2H-azirines to acylketenes: a route to N-bridgehead heterocycles

Reactions of acylketenes, generated from diazo diketones, with 2-unsubstituted and 2-monosubstituted 3-aryl-2H-azirines lead to 1:1 or 2:1 adducts, which are derivatives of 5-oxa-1-azabicyclo[4.1.0]hept-3-ene or 5,7-dioxa-1-azabicyclo[4.4.1]undeca-3,8-diene. According to DFT B3LYP/6-31G(d) computations, the formation of (4+2)-monoadducts proceeds via a stepwise non-pericyclic mechanism. Reaction with methanol transforms quantitatively both 1:1 and 2:1 adducts into 1,4-oxazepine derivatives.     

Electroreductive intermolecular coupling of phthalimides with aldehydes: application to the synthesis of alkylideneisoindolin-1-ones

The electroreduction of N-methyl, N-p-anisyl, and N-unsubstituted phthalimides with aldehydes in the presence of chlorotrimethylsilane and triethylamine gave intermolecularly coupled products, 3-hydroxy-3-(1-hydroxyalkyl)isoindolin-1-ones. The coupling products were reduced with Et₃SiH/BF₃·Et₂O to 3-(1-hydroxyalkyl)isoindolin-1-ones, which were dehydrated to alkylideneisoindolin-1-ones. From N-unsubstituted phthalimides, Z-isomers of alkylideneisoindolin-1-ones were obtained stereospecifically.     

Reaction of 2-dimethylaminomethylene-1,3-diones with dinucleophiles. II. Synthesis of 5-(alkyl)(phenyl)-4-acylisoxazoles and 6,7-dihydro-1,2-benzisoxazol-4(5H)-ones

The reaction of open-chain and cyclohexane sym-2-dimethylaminomethylene-1,3-diones with hydroxylamine hydrochloride in refluxing methanol gave in good to moderate yields a series of 5-(alkyl)(phenyl)-4-acylisoxazoles and 6,7-dihydro-1,2-benzisoxazol-4(5H)-ones, respectively. As 3-unsubstituted isoxazoles, all these compounds easily isomerized with sodium methoxide to the corresponding 2-cyano-1,3-diones in high yields.     

Recyclization of 1,3,4-Oxadiazoles and Bis-1,3,4-oxadiazoles into 1,2,4-Triazole Derivatives. Synthesis of 5-Unsubstituted 1,2,4-Triazoles

Efficient methods have been developed for obtaining precursors of stable carbenes, viz. 5-unsubstituted 3,4-diaryl-1,2,4-triazoles and 3,3′- or 4,4′-bridge linked bis-1,2,4-triazoles, by the recyclization of 5-unsubstituted 1,3,4-oxadiazoles or p-phenylenebis-1,3,4-oxadiazole with anilines or aromatic diamines in the presence of trifluoroacetic acid or with aniline hydrochlorides in pyridine. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1026–1032, July, 2005.     

Synthesis of some isomeric 4-ethoxycarbonyl-3-and 5-(1- and 2-hydroxyalkyl)-1,3- and 1,5-dimethylpyrazoles from 3-(2H)furanones and 2,3-dihydro-4-pyrones

The title compounds were prepared by reaction of 3-(2H)furanones and 2,3-dihydro-4-pyrones with methylhydrazine or alternatively by methylation of the corresponding N-unsubstituted pyrazoles. ¹³C and ¹H nmr were used to assign the isomeric 3-methyl or 5-methyl structures.     

Novel Biginelli-like three-component cyclocondensation reaction: efficient synthesis of 5-unsubstituted 3,4-dihydropyrimidin-2(1H)-ones

Iron (III) catalyzed the three-component Biginelli-like cyclocondensation reaction efficiently in acetonitrile to afford the corresponding 5-unsubstituted 3,4-dihydropyrimidin-2-(1H)-ones in high yields. The first Biginelli-like reactions of urea, aldehydes and ketones were furnished important new 3,4-dihydropyrimidin-2-(1H)-ones derivatives suitable for further study.