Diene synthesis with 5-chloro-1-alkyl-2-pyridones

For the first time, we describe the diene synthesis of 5-chloro-1-alkyl-2-pyridones with N-phenylmaleic imide and have shown that the reaction proceeds nonstereoselectively with formation of a mixture of [4+2]cycloadducts with anendo andexo configuration. We have obtained 1,4-cycloadducts with 4-phenyl-1,2,4-triazoline-3,5-dione.M. V. Lomonosov Moscow State University, Moscow 119899. Translated from Khimiya Geterotsklicheskikh Soedinenii, No. 5, pp. 687–691, May, 1997.     

Diene synthesis with 2-pyrones and 2-pyridones. 31. Stereochemistry of the successive addition of two different dienophiles to 2-pyrones

The stereochemistry of the successive addition of two different dienophiles, viz., N-phenylmaleinimide and 4-phenyl-1,2,4-triazoline-3,5-dione, to 2-pyrones was studied. The configurations of the mixed adducts (bisimides) obtained were established by PMR and mass spectrometry. It is shown that in all cases the reactions proceed with the formation of mixtures of syn and anti isomers, the ratios of which depend on the positions of the methyl groups in the starting 2-pyrones.See [1] for communication 30.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1471–1476, November, 1982.     

Bromination of 1-alkyl-2-pyridones

The corresponding monobromides were obtained in the bromination of 1-alkyl-2-pyridones with bonded bromine (with N-bromosuccinimide and dioxane dibromide). The conditions under which the yields of the mixtures of isomers were 60–80%, and almost no dibromides were obtained, were found. It was established that the ratios of the 3- and 5-bromo isomers depend on the character of the brominating agent.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1662–1664, December, 1982.     

Chelate synthesis of 1-alkyl-2-methyl-3-cyano-4-pyridones from diacetylketene N,S-acetal

N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1455–1456, June, 1992.     

2-Methylpyridinium salts as 1,4-dinucleophiles. IV. Westphal condensation with 2-alkyl-1-aminoazinium substrates

Condensation of 2-alkyl-1-aminopyridinium, quinolinium or 1-alkyl-2-aminoisoquinolinium salts with 1,2-acenaphthenequinone or 9,10-phenanthrenequinone in the presence of base, gave pyrido[1,2-b]pyridazinium salts in good yields.     

Products from metallation and attempted metallation of 1-alkyl-4,6-diphenyl-2-pyridones and subsequent reaction with electrophiles

The title pyridones form products in which either their own carbanion, or an alkylcarbanion, has added to the 3-position, followed by an electrophile to the 4-position.     

Highly enantioselective photocyclization of 1-alkyl-2-pyridones to beta-lactams in inclusion crystals with optically active host compounds

[reaction: see text] Upon photoirradiation of a 1:1 inclusion complex of (-)-3 and 2-alkyl-1-pyridone (1) (R = Et, n-Pr, i-Pr, n-Bu, i-Bu) in the solid state, optically active beta-lactams (2) of 91-99.5% ee were obtained in good yield.     

Reactions of 2-alkyl-, 2-phenyl- and 2-alkoxy-1,2-oxaborolanes with (dichloromethyl)lithium. A novel synthesis of 1,4-alkanediols.

Two novel alternative procedures for the synthesis of 1,4-alkanediols were described by involving the reactions of (dichloromethyl)lithium with some 1,2-oxaborolane derivatives readily obtainable from allyl alcohol.     

Photochemical reaction of 7-aminocoumarins. 9. [2+2]-Cycloadducts with trans,trans-1,4-diphenyl-1,3-butadiene

The photoreactions of 7-diethylaminocoumarin, 4-methyl-7-diethylaminocoumarin, 4-trifluoromethyl-7-diethylaminocoumarin, and 4-N-morpholino-7-diethylaminocoumarin with trans,trans-1,4-diphenyl-1,3-butadiene, which lead to the formation of [2+2]-cycloaddition products, were studied. It was established that photocycloaddition proceeds with the formation of adducts that have a 1-endo-styryl substituent and a 2-exo-phenyl group. The effect of the substituent in the 4-position of the 7-aminocoumarin molecule on the effectiveness of cycloaddition is discussed.See [1] for Communication 8.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1319–1325, October, 1990.     

Diene synthesis with levo-pimaric acid

Summary The diene condensations of levo-pimaric acid with acrolein, acrylonitrile, vinyl acetate, and methyl acrylate were carried out and the corresponding adducts were isolated.     

Studies on quinoline derivatives and related compounds. 1. A new synthesis of 1-alkyl-1,4-dihydro-4-oxo-3-quinolinecarboxylic acids

A novel preparative method for 1-alkyl-1,4-dihydro-4-oxo-3-quinolinecarboxylic acids was developed. The key process is the cyclization of N-alkylanilinomethylenemalonales, which was effected successfully in the presence of polyphosphoric acid, polyphosphate ester, boron tri-fluoride or a mixture of acetic anhydride and sulfuric acid. With phosphorus oxychloride, N-alkylanilinomethylenemalonates yielded 1-alkyl-4-chloro-3-carbethoxyquinolinium salts which were hydrolyzed readily to ethyl 1-alkyl-1,4-dihydro-4-oxo-3-quinolineearboxylates or their acids. By means of this novel method several new 1-alkyl-1,4-dihydro-4-oxo-3-quinolineearboxylic acids were prepared.     

Versatile synthesis of 3,5-disubstituted 2-fluoropyridines and 2-pyridones

5-bromo-2-fluoro-3-pyridylboronic acid (3) was prepared in high yield by ortho-lithiation of 5-bromo-2-fluoropyridine (1), followed by reaction with trimethylborate. Suzuki reaction of 3 with a range of aryl iodides gave 3-monosubstituted 5-bromo-2-fluoropyridines 4 in excellent yields. A second Suzuki reaction utilizing the bromo constituent of 4 with aryl and heteroaryl boronic acids provided 3,5-disubstituted 2-fluoropyridines 5, which in turn could be converted to the corresponding 2-pyridones 6.     

Synthesis of indolo-α-pyrones,indolo-α-pyridones,and indolopyrylium salts

A method has been developed for obtaining indolo--pyrones by acylation of 3-indolylacetic acid and its N-methyl derivatives. Indolo--pyrones form indolo--pyridones by refluxing with ammonium acetate in acetic acid. Indolo[2,3-c]pyrylium salts were obtained by acylation of 4-methoxyand 3,4-dimethoxy-3-phenacylindoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 345–349, March, 1971.     

Novel and efficient synthesis of 4-sulfonyl-2-pyridones

Heterocyclic 4-sulfonyl-2-pyridones represent useful scaffolds for drug discovery, and are also versatile synthetic building blocks. Herein, we describe a novel and efficient synthesis of this heterocyclic ring system utilizing an acid-mediated cyclo-condensation reaction. This synthetic method affords convenient access to structurally diverse N-substituted 4-sulfonyl-2-pyridones in moderate to good yields.     

Regio- and selective synthesis of 4,6-disubstituted-2-pyridones

Palladium catalysed regio- and stereoselective annulation of allenyl stannanes by β-iodo vinylic amides gives good yields of the corresponding 2-pyridones. This annulation probably occurs via a Stille reaction/cyclisation sequence.     

Reaction of N-phenylmaleinimide with 2- and 4-vinylpyridines

The reaction of 2- and 4-vinylpyridines with N-phenylmaleinimide in acetic anhydride proceeds via the scheme of the diene synthesis and leads to pyrrolo[3,4-f]-quinoline and pyrrolo[3,4-i]isoquinoline derivatives.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1075–1078, August, 1980.     

Microwave-assisted one-pot regioselective synthesis of 2-alkyl-3,4-dihydro-3-oxo-2H-1,4-benzoxazines

A protocol for regioselective one-pot synthesis of 2-alkyl-3,4-dihydro-3-oxo-2H-1,4-benzoxazines under controlled microwave heating has been developed. Starting from commercially available 2-aminophenols, a base-mediated regioselective O-alkylation took place with 2-bromoalkanoates to give the acyclic intermediates, which underwent spontaneously an intramolecular amidation reaction to furnish 2-alkyl-3,4-dihydro-3-oxo-2H-1,4-benzoxazines in 44-82% yields. For the acyclic intermediate possessing an electron-withdrawing group, microwave heating was necessary for the annulation reaction.