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

Russian Journal of General Chemistry -     

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.     

Synthesis of optically active 2-alkoxy-2H-pyran-3(6H)-ones. Their use as dienophiles in Diels-Alder cycloadditions.

Optically active 2-alkoxy-2H-pyran-3(6H)-ones (4a-d) were synthesized in one step by the tin(IV) chloride-promoted glycosylation and rearrangement of the 2-acetoxy-3,4-di-O-acetyl-D-xylal (3) prepared from D-xylose (1). The absolute configuration of the new stereocenter at C-2 was determined by chemical transformation of the dihydropyranones 4a and 4b into the known alkyl pentopyranosides (7a and 7b, respectively). Also, from (1)H NMR experiments using a chiral ytterbium shift reagent, the enantiomeric excesses for 4a (>86%) and 4b (>77%) were established. Enantiomerically pure 4c and 4d were obtained by reaction of 3 with chiral 2-octanol (R and S, respectively). Dihydropyranones 4a-d were employed as dienophiles in Diels-Alder cycloadditions with 2,3-dimethylbutadiene and butadiene. Under thermal conditions, only moderate yields (approximately 50%) of cycloadducts 9a-c and 10a were respectively obtained with good diastereofacial selectivity (>80%). Optimized Lewis acid promoted cycloadditions led to 9a-d and 10a,c in higher yields (approximately 80%) and with higher diastereoselectivities (>94%). The major products were formed by approach of the dienes from the less hindered face of the dihydropyranones, and the minor products (such as 11a) were formed by addition from the opposite side. Furthermore, cycloadduct 9a was stable in an alkaline solution, whereas 11a underwent epimerization under the same conditions.     

The Synthesis of 6-Hydroxy-2H-pyran-3(6H)-onyl-hexoses,Potential Precursors of Disaccharides

6-Hydroxy-2H-pyran-3(6H) -one (1)¹, a highly functionalized synthone, was recently employed for the synthesis of pyromeconic acid², phosphorus containing sugars³, and for the synthesis of all stereoisomeric pentoses⁴. Formation of a glycosidic linkage between 1 and monosaccharides would open an access to a variety of disaccharides via the proper modification of the 3-pyrone moiety.     

Products from furans. XV. Synthesis of novel tyramine derivatives via 6-hydroxy-2H-pyran-3(6H)-ones

Furan chemistry was utilized for the synthesis of several novel tyramine derivatives. Thus 2H-pyran-3(6H)-ones were used as keystone intermediates for the preparation of novel α,β-disubstituted tyramine derivatives. Furthermore by the same approach tyramine was derivatized with a molecule of GABA.     

Reactions of 6-Alkoxy(alkylthio)carbonylamino-4-hydroxy-2H-pyran-2-ones with Some Electrophilic Reagents

Alkoxy(alkylthio)-4-hydroxy-2H-pyran-2-ones readily react with electrophiles to give substitution products at C³. Hard electrophilic reagents replace hydrogen both in position 3 and in position 5 of the pyran ring. Methylation of 6-alkoxy(alkylthio)-4-hydroxy-2H-pyran-2-ones with diazomethane leads to formation of O- and N-methyl derivatives.     

Synthesis of 1,5-Disubstituted 3-(4-Hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-2-pyrazolines

Summary. A series of 1,5-disubstituted 3-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-2-pyrazolines were synthesized by the reaction of α,β-unsaturated ketones derived from dehydroacetic acid and hydrazine in hot acetic acid or propionic acid. The structures of all new compounds were elucidated by microanalyses, ¹H and ¹³C NMR, IR, and mass spectroscopic measurements.     

6-羟基-3,4-二氢-2(1H)喹啉酮合成新方法

提出了一种以苯胺和3-氯丙酰氯为原料，经环合、硝化、还原、重氮化水解合成目标产物6-羟基-3，4二氢-2(1H)喹琳酮的新方法。此法合成的目标产物产率高，总产率达67％以上。单步产率均在86．5—99．6％之间，反应条件温和。各步产品经MS，1HNMR进行定性及结构表征。     

Reactions of 4-Hydroxy-5-methyl(phenyl)-2-styryl-6H-1,3-oxazin-6-ones with Nucleophiles

4-Hydroxy-5-methyl(phenyl)-2-styryl-6H-1,3-oxazin-6-ones react with hydrazine and phenylhydrazine to give the corresponding 3,5-substituted triazoles. Treatment of the title compounds with ethanol and methanol leads to formation of N-cinnamoylmalonamates. The structure of the products was confirmed by the IR and ¹H and ¹³C NMR spectra.     

3-Hydrazino-1,2,4-triazin-5(2H)-ones in Reactions with Compounds Containing Carbonyl and Active Methylene Groups

Boiling of ethyl cyanoacetate with 6-tert-butyl-3-hydrazino-1'2'4-triazin-5(2H)-one in alkalinemedium yielded 6-tert-butyl-3-(5-hydroxy-3-oxo-2'3-dihydro-1H-pyrazol-1-yl)-1'2'4-triazin-5(2H)-one.Acylation of 6-tert-butyl-3-hydrazino-1'2'4-triazin-5(2H)-one with benzoyl chloride furnished 3-benzoyl-hydrazido-1'2'4-triazine that cyclized when treated with POCl₃ providing a derivative of[1'2'4]triazolo[4'3-b][1'2'4]triazine. Boiling of 6-tert-butyl-3-hydrazino-1'2'4-triazin-5(2H)-one in glacialacetic acid gave rise to diacetylated derivative whereas the boiling with acetic anhydride in an inert solventafforded monoacetylated product.     

Synthesis of Some Heterocyclic Compounds from Enamines of 3-Acetylfuran-2(5 H)-ones

The interaction of different 3-acetylfuran-2(5H)-ones (1, 4) with dimethylformamide dimethyl acetal (DMF/DMA) has been investigated, and the condensed furopyridine system 3 was obtained. By means of interaction of compounds 4 and DMF/DMA via the 3-acetylfuran-2(5H)-one enamines, the heterocyclic substituted furanones are obtained. The condensation of 3-acetyl-4,5,5-trimethylfuran-2(5H)-one (1a) with veratraldehyde was realized. Through the interaction of 1a with malononitrile and further intramolecular condensation of the product, 6-amino-dihydroisobenzofuran-5-carbonitrile was also synthesized.     

A Short Synthesis of 4- and 6-Azaindol-2(3H)-ones

Although indol-2(3H)-ones possess a wide range of pharmacological¹ and microbiological² activities, the corresponding azaindol-2(3H)-ones have stimulated little interest. Successful syntheses have been reported for the title compounds^3,4 involving several stages which in our hands gave a variety of side products, especially in the hydrogenation stage.     

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.

     

Products from furans. V Synthesis of oxygen containing isosteres of sympathomimetic amines via 6-hydroxy-2H-pyran-3(6H)-ones and their cis-platinum(II) complexes

Novel amino analogues of sympathomimetic amines, which contain the pyran ring as a consequence of their common route of preparation, were synthesized. A modified Strecker reaction on tetrahydro-2H-pyran-3-one derivatives yielded α-benzylamino nitriles, which upon subsequent hydrogenation and hydrogenolysis gave the target 1,2-diamines. The prepared diamines were indeed sympathomimetic on the basis of molecular mechanics studies, since they have been found to fulfill earlier considerations on the minimal structural requirements, necessary to attain high affinity to dopamine (DA) receptors. Furthermore the prepared 1,2-diamino compounds were used as ligands for the synthesis of cis-Platinum(II) complexes.     

Synthesis of 3-S-hetaryl-substituted pyridin-2(1H)-ones and 5,6-dihydropyridin-2(1H)-ones*

A method has been developed for the synthesis of 3-S-hetaryl-substituted pyridin-2(1H)-ones and 5,6-dihydropyridin-2(1H)-ones based on the base catalyzed cyclization of N-(3-oxoalkyl)- and N-(3-oxoalkenyl)amides which contain a divalent sulfur atom in an α-position to a carbamoyl group and bound to the heterocycle.     

Synthesis of 2-Acyl- and 2-Sulfonylbenzisoselenazol-3(2H)-ones

Synthesis of two new groups of organoselenium compounds: 2-acyl-and sulfonylbenzisoselenazol-3(2H)-ones (3, 4), potential immunostimulants, in two alternative ways was elaborated. One of them was based on the reaction of 2-chlorobenzoyl chloride (2) with primary amides while the second one involved N-acylation or N-sulfonylation of benzisoselenazol-3(2H)-one (5) with acid chlorides. Two exceptions from general reaction of dichloride 2 with amides were observed. Thioacetamide produced 2,1-benzothiaselenophenone (6), and urea gave 6,7-benzo-2,4-diaza-1-selenacyclohepta-3,5-dione (7).