A synthesis of carbasugar-sugar pseudodisaccharides via a cycloaddition-cycloreversion reaction of 2H-pyran-2-ones

Cycloaddition of 3-carbomethoxy-2H-pyran-2-one to a vinylated sugar followed by the loss of bridging CO(2) from the cycloadduct affords a cyclohexadiene which can be manipulated to a carbasugar-sugar pseudodisaccharide.     

Tandem reaction of 3-hydroxyhexa-4,5-allenic esters: a novel access to diversely substituted 2H-pyran-2-ones and indenes

A highly efficient synthesis of diversely substituted 2H-pyran-2-ones and indenes through Br?nsted acid promoted tandem reaction of the readily obtainable 3-hydroxyhexa-4,5-allenic esters under extremely mild conditions has been developed.     

The synthesis of methyl 2-(benzyloxycarbonyl)amino-3-dimethylaminopropenoate. The synthesis of trisubstituted pyrroles, 3-amino-2H-pyran-2-ones,fused 2H-pyran-2-ones and 4H-pyridin-4-ones

Methyl 2-(benzyloxycarbonyl)aimno-3-dimemylaminopropenoate ( 2 ) was prepared from methyl N-(benzyloxycarbonyl)glycinate ( 1 ) and t-butoxybis(dimethylamino)methane, and used as a reagent for preparation of substituted 3-(benzyloxycarbonyl)amino-4H-quinolizin-4-ones 5 and 6 , ?2H-pyran-2-ones 17–19 , ?2H-1-benzopyran-2-ones 28–31 , and -naphthopyrans 32–35 , ?2H-pyrano[3,2-c]pyridine-2,5-dione 46 , -pyrano-[4,3-b]pyran-2,5-dione 47 , -pyrano[3,2-c]benzopyran-2,5-dione 48 , -pyrano[2,3-c]pyrazol-6-ones 49 and 50 , -pyrano[2,3-d]pyrirnidin-7-ones 51 and 52 derivatives. In the reaction of 2 with 1,3-diketones trisubsti tuted pyrroles 14–16 were formed. Selective removal of benzyloxycarbonyl group was achieved by cat alytic transfer hydrogenation with Pd/C in the presence of cyclohexene to afford free 3-amino compounds 7 , 8 , 20 , 36–38 and 53–57 in yields better than 80%.     

Stereochemistry of ethynylation reaction of C2 isomeric 1,2-dimethyldecahydroquinol-4-ones

Conclusions The stereochemistry of the ethynylation reaction of the C₂ epimers of 1,2-dimethyldecahydroquinol-4-ol with sodium acetylide in liquid ammonia has been studied and the conformation of the acetylene alcohols formed by this has been established.Translated from Izvestiya Akademii Nauk SSSR, SeriyaKhimicheskaya, No. 4, pp. 900–903, April, 1970.     

Parallel synthesis of 3-amino-4H-quinolizin-4-ones, fused 3-amino-4H-pyrimidin-4-ones, and fused 3-amino-2H-pyran-2-ones

On the basis of the enaminone methodology, libraries of 3-amino-4H-quinolizin-4-ones, fused 3-amino-4H-pyrimidin-4-ones, and fused 3-amino-2H-pyran-2-ones were synthesized by the solid-phase and by the solution-phase parallel synthesis. The solution-phase approach turned out to be advantageous over the solid-phase approach. The solution-phase synthesis afforded, in most cases, analytically pure products in high yields, whereas the solid-phase approach gave products in poor yields and in low purity.     

Preparation and reactions of 3,4-dihydro-2H-pyran-2-ones

The Michael reaction of ethyl cinnamates with deoxybenzoin gave ethyl 3,4,5-triaryl-5-oxopentanoates which were hydrolysed to the corresponding acids. The latter could be cyclized to the respective 3,4-dihydro-2H-pyran-2-ones which underwent ring opening with several nucleophiles to the corresponding acid derivatives. However, their reaction with ammonium acetate led to the formation of 3,4-dihydro-2-pyridones. The 3,4-dihydro-2-pyrones and pyridones were dehydrogenated to the corresponding 2-pyrones and 2-pyridones by fusion with sulfur.     

Effect of allylic strain on the conformations of diphenyl-substituted tetrahydro-1,3-oxazin-2-ones and hexahydropyrimidin-2-ones

The conformations of the cis and trans isomers of 4,6-diphenyl-, 4,5-diphenyl- and 5,6-diphenyltetrahydro-1,3-oxazin-2-one and 4,5-diphenylhexahydropyrimidin-2-one, and of some of their N-substituted derivatives, have been studied by ¹H NMR. Conformers with 4a, 6e-, 4a, 5e- and 5a, 6e-phenyl groups are preferred in the respective isomers of the N-H oxazinones, confirming a half-chair conformation of the ring. Allylic strain caused by N-substituents shifts strongly the a,e?e, a equilibria in trans-4,6-diphenyl- and cis-4,5-diphenyl-oxazinones, but only moderately the e,e?a,a equilibria in the compounds with trans-vicinal phenyl groups. In the latter, the diaxial conformation is preferred only in the case of bulky N-substituents. The diaxial conformation is more favoured in the trans-4,5-diphenylpyrimidones.     

N,N-Disubstituted 4-amino-3-chloro-5,6-polymethylene-2H-pyran-2-ones

The title compounds were obtained by dehydrochlorination with collidine, DBN or triethyl-amine of N,N-disubstituted 4-amino-3,3-dichloro-3,4-dihydro-5,6-polymethylene-2H-pyran-2-ones already described.     

Synthesis and reactions of 3-iodo-4H-pyran-4-ones

3-Iodo-4H-pyran-4-ones have been synthesised in excellent yield by the reaction of acetylenic β-diketones with iodine monochloride and were converted into the corresponding 4H-pyran-4-thiones. The iodopyrones and thiopyrones gave with methylamine the respective N-methylpyridones and thiopyridones. The structure of the above compounds was confirmed from their spectral characteristics.     

Remarkable O(2)-effect in 1,4-additions of diethylzinc to 6-acyloxy-2H-pyran-3(6H)-ones and 6-alkoxy-2H-pyran-3(6H)-ones

Under the influence of air, a facile 1,4-addition of diethylzinc to acyloxypyranones and alkoxypyranones 1 takes place. Reaction of diethylzinc with molecular oxygen provides EtOOZnEt, which catalyzes the addition of diethylzinc.     

Solid phase synthesis of tetrahydro-1,4-benzodiazepin-2-ones

A novel solid phase route to tetrahydro-1,4-benzodiazepin-2-ones is described which involves construction of a core template in solution followed by diverse derivatization on solid phase.     

Reactions of 4-Hydroxy-2H-pyran-2-ones with Some N-Nucleophiles

Russian Journal of General Chemistry -     

Synthesis of some schiff bases of 3-aroyl-6-aryl-4-hydroxy-2H-pyran-2-ones

Summary The reaction of 3-aroyl-6-aryl-4-hydroxy-2H-pyran-2-ones (Ar=p-tolyl, 1,1-biphenyl-4-yl or thienyl) with aniline and substitutedo-phenylenediamine (R=H, CH₃ or Cl) yields a series of new Schiff bases2a–f in 51–72% yield. Bromination of1a gave the 5-bromo derivative1c, while the compounds1a,1b,2b,2e, and2f were converted into 2,6-diaryl-4H-pyran-4-ones3a–c. All products have been fully characterized.

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Synthese von Schiff'schen Basen von 3-Aroyl-6-aryl-4-hydroxy-2H-pyran-2-onen

Zusammenfassung Die Reaktion von 3-Aroyl-6-aryl-4-hydroxy-2H-pyran-2-onen (Ar=p-Tolyl, 1,1-Biphenyl-4-yl oder Thienyl) mit Anilin und substituierteno-Phenylendiaminen liefert neue Schiff'sche Basen2a–f/bd in 51–72% Ausbeute. Bromierung von1a gab das 5-Bromderivate1c, während die Verbindungen1a,1b,2b,2e und2f in 2,6-Diaryl-4H-pyran-4-onen3a–c übergeführt wurden. Alle Produkte wurden voll charakterisiert.

     

Acetyltrimethylsilane: a novel reagent for the transformation of 2H-pyran-2-ones to unsymmetrical biaryls

[reaction: see text] An expeditious synthesis of unsymmetrical biaryls functionalized with electron-withdrawing or -donating substituents is described and illustrated by carbanion-induced ring transformation of 2H-pyran-2-one using acetyltrimethylsilane (ATMS) as a novel reagent in good yield. The novelty of the reaction lies in the creation of an aromatic ring from 2H-pyran-2-ones via two-carbon insertion from ATMS used as a source of carbanion.     

Bromination of aromatic ring of tetrahydro-1,5-benzodiazepin-2-ones

Novel mono- or dibromo-substituted tetrahydro-1,5-benzodiazepinones were obtained by direct bromination of the corresponding 2,3,4,5-tetrahydro-(1H)-1,5-benzodiazepin-2-ones and 5-N-alkyl (or formyl) derivatives with bromine. Substituent effects and the orientation of the entering groups in the bromination reaction are discussed.Institute of Biochemistry, Vilnius LT-2600, Lithuania; c-mail: apalaima@bchi.lt. Translated from Khimiya Geterotsiklicheskikh Socdinenii, No. 6, pp. 799–805, June, 2000.     

Synthesis of tetrahydro-1,4-benzodiazepine-2-ones on hydrophilic polyamide SynPhase lanterns

Solid-phase synthesis is greatly dependent on the solid support. Here, we report the use of a new hydrophilic grafted surface on SynPhase lanterns in solid-phase organic chemistry. A convenient and facile solid-phase synthesis of disubstituted 1,4-benzodiazepine-2-ones on polyamide SynPhase lanterns is described. The key step of the synthesis involved a reduction-cyclization of a nitroaryl methyl ester with a mixture of tin(II) chloride dihydrate and ammonium acetate in water and ethanol at elevated temperature to give the desired target compounds. A library of 21 disubstituted 1,4-benzodiazepine-2-ones was prepared.     

Microwave assisted synthesis of 3-benzazepin-2-ones as building blocks for 2,3-disubstituted tetrahydro-3-benzazepines

Microwave assisted condensation of primary amines with keto acids 1a–c provided directly 3,4-disubstituted 1,3-dihydro-3-benzazepin-2-ones 2. Whereas small amine size, such as NH₃ afforded high yields of secondary lactams 2a, 2d, and 2g, primary amines with larger substituents in α-position led to lower yields of 2 or even to regioisomeric indanone derivatives 4. However, subsequent alkylation of 2a, 2d, and 2g with various alkyl halides provided the corresponding N-substituted 3-benzazepin-2-ones 2 in good yields. Hydrogenation of 2 followed by BH₃ reduction led to 3-benzazepines 9. 3-Benzyl-2-methyl-2,3,4,5-tetrahydro-1H-3-benzazepine (9c) reveals high σ₁ affinity and selectivity over σ₂ and NMDA receptors.     

Synthesis of aminonicotinonitriles and diaminopyridines through base-catalyzed ring transformation of 2H-pyran-2-ones

An efficient and convenient synthesis of 2-amino-6-aryl-4-methylsulfanylnicotinonitriles (2), 2-amino-6-aryl-4-substituted-aminonicotinonitriles (4), and 2-amino-6-aryl-4-substituted-aminopyridines (6) has been delineated and illustrated through base-catalyzed ring transformation of 6-aryl-3-cyano-4-methylsulfanyl/substituted-amino-2H-pyran-2-ones (1, 3, and 5) with cyanamide and ammonium carbonate separately.     

Novel application of Leuckart-Wallach reaction for synthesis of tetrahydro-1,4-benzodiazepin-5-ones library

A novel and efficient strategy has been developed to synthesize privileged tetrahydro-1,4-benzodiazepines with excellent yields and purities; this synthetic pathway was established by the revitalization of the Leuckart-Wallach (LW) reaction via solid-phase synthesis.     

Brominated derivatives of 4-hydroxy- and 4-methoxy-6-methyl-2H-pyran-2-ones

Twenty-five different brominated derivatives of 4-hydroxy-6-methyl-2-pyrone (triacetic acid lactone) and 3-acetyl-4-hydroxy-6-methyl-2-pyrone (dehydroacetic acid) have been prepared. Fifteen derivatives have not been previously described and the preparations of a few known products have been improved. Bromination at C-3, C-5, methyl group at C-6 and deacetylations at C-3 have been the types of reactions used.