Reaction of 5,5-dialkyl-2-halo-6-hydroxy-5,6-dihydro-1H-pyridine-3,4,4-tricarbonitriles with alcohols

Russian Journal of Organic Chemistry -     

Three-component synthesis of 2-halo-6-methoxy-5,6-dihydropyridine-3,4,4(1H)-tricarbonitriles

Russian Journal of Organic Chemistry - One-stage preparation method of 2-halo-6-methoxy-5,6-dihydropyridine-3,4,4(1H)-tricarbonitriles was developed, consisting in the reaction of...     

Tricomponent domino synthesis of 6-hydroxy-2-chloro-1,4,5,6-tetrahydropyridine-3,4,4-tricarbonitriles

In reaction of tetracyanoethylene with ketones and HCl in 1,4-dioxane at 30–40°? 6-hydroxy-2-chloro-1,4,5,6-tetrahydropyridine-3,4,4-tricarbonitriles are formed.     

Photoaddition of Ethyl 2,2-Dimethyl-5-oxo-5,6-dihydro-2H-pyridine-1-carboxylate to 2,3-dimethylbut-2-ene

On irradiation (350 nm) in the presence of excess 2,3-dimethylbut-2-ene, the newly synthesized title compound 5 affords as main products the unexpected cyclopropylpyrrolidine 10 (50%) and the spiro-oxetane 9 (25%).     

Reaction of 2-methyl-5,6-dihydro-2H-pyran with dichlorocarbene

Upon treatment of 2-methyl-5,6-dihydro-2H-pyran with dichlorocarbene there are formed products of addition to the double bond and insertion at the C-H bond giving cis- and trans-7,7-dichloro-2-methyl-3-oxabicyclo[4.1.0]heptane and 2-dichloromethyl-2-methyl-5,6-dihydro-2H-pyran.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 190–191, February, 1986.     

Reaction of 3,3-dialkyl-6-trifluoromethyl-2,3-dihydro-4-pyrones with hydrazine hydrate

3,3-Dialkyl-2,3-dihydro-6-trifluoromethyl-4-pyrones react with hydrazine hydrate to give 2-hydrazino-2-trifluoromethyl-4-tetrahydropyrone hydrazones. When heated, the latter are transformed into 3(5)-(2-hydroxyethyl)-5(3)-trifluoromethylpyrazoles, while their treatment with HCl in ether leads to 3,3-dialkyl-2,3-dihydro-6-trifluoromethyl-4-pyrone azines.     

Selective quasi-hydrolysis of cyano group in 6-hydroxypiperidine-3,4,4-tricarbonitriles

Reactions of 3,3-dialkyl-4-oxoalkane-1,1,2,2-tetracarbonitriles with water in the presence of pyruvic acid are accompanied by selective quasi-hydrolysis of cyano groups in intermediate 6-hydroxypiperidine-3,4,4-tricarbonitriles.     

Synthesis of 6-hetaryl-5,5-dialkyl-3,3-dimethyl-tetrahydropyran-2,4-diones by Reformatsky Reaction

Zinc enolates derived from ethyl 4-bromo-2,2,4-trimethyl-3-oxopentanoate and 4-bromo-4- ethyl-2,2-dimethyl-3-oxohexanoate react with 2-furan-, 2-thiophene-, 1-(3-nitrophenyl)-2-pyrrole-, 1-acyl-3-indole-, and 2-pyridinecarbaldehydes to give the corresponding 6-hetaryl-5,5-dialkyl-3,3-dimethyltetrahydropyran-2,4-diones.Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 10, 2004, pp. 1549–1551.Original Russian Text Copyright © 2004 by Shchepin, Korzun, Sazhneva.     

Investigation of paths for the synthesis of 5,5-dialkyl-3-perfluoroalkyl-5,6-dihydro-1,2,4-triazolo[3,4-a]isoquinolines

Substituted 3-trifluoromethyl-5,6-dihydro-1,2,4-triazolo[3,4-a]isoquinolines were obtained by the reaction of substituted 1-methylthio-3,4-dihydroisoquinolines with hydrazine hydrate and trifluoroacetic acid. The corresponding 3-perfluoroalkyl derivatives are formed in the course of dehydration of 2-(3,3-dimethyl-3,4-dihydro-1-isoquinolyl)hydrazides of perfluorocarboxylic acids.Institute of Technical Chemistry, Ural Branch, Russian Academy of Sciences, Perm. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 380–386, March, 2000.     

Reaction of dichlorocarbene with 2,3-dihydro-5,6-dimethyl-1,4-oxathiin and 2,3-dihydro-5,6-dimethyl-1,4-dithiin

Dichlorocarbene, generated from ethyl trichloroacetate and sodium ethoxide, reacts with 2,3-dimethyl-5,6-dihydro-1,4-oxathiin to give 7,7-dichloro-1,6-dimethyl-2-oxa-5-thiabicyclo[4,1,0]heptane, and with 2,3-dimethyl-5,6-dihydro-1,4-dithiin to give 6-chloro-2,3-dihydro-7-methyl 5-methylene-5(H)-1,4-dithiepin. Both products were oxidised to the corresponding sulfone.     

A facile synthesis of 5,6-dihydro-5-hydroxy-2(1H)-pyridone

A short synthesis of 5,6-dihydro-5-hydroxy-2(1H)-pyridone was achieved from l-serine employing Horner-Emmons olefination as the key step.     

A rapid and diverse construction of 6-substituted-5,6-dihydro-4-hydroxy-2-pyrones through double Reformatsky reaction

A rapid and diverse synthesis of biologically important 6-substituted-5,6-dihydro-4-hydroxy-2-pyrones through a double Reformatsky reaction of aldehydes to δ-hydroxy-β-ketoesters followed by lactonization is described. Due to the high functional group tolerance and reaction site discrimination between aldehyde, nitrile, and ester groups in the substrate, the protocol can provide the dihydropyrones with bromo, nitro, carboxylic acid, and β-ketoester groups, which are suitable for the further derivatizations. Furthermore, the protocol has been successfully applied to the rapid total synthesis of naturally occurring Yangonin.     

Reaction of 2-alkoxy-2-methylthio-5,6-dihydro-4H-1,3-thiazines with phenoxyacetyl chloride

The reaction of 4-alkoxytetrahydro-1, 3-thiazine-2-thiones with methyl iodide and subsequent treatment of the resultant S-alkylation products by suitable sodium alcoholates yielded 4-alkoxy-2-methylthio-S, 6-dihydro-4H-1, 3-thiazines, which upon reaction with phenoxyacetyl chloride in the presence of triethylamine was stereospecifically converted into 4-alkoxy-6-methylthio-7-phenoxvcephams.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 557–560, April, 1996.     

Synthesis and chemical transformations of tert-butyl-4-vinyl-3,6-dihydro-2H-pyridine-1-carboxylate

Reaction of tert-butyl-1,2,3,6-tetrahydro-4-[(trifluoromethyl)sulfonyl]pyridine-1-carboxylate with tributylvinyltin in the presence of Pd(PPh₃)₄-LiCl afforded tert-butyl-4-vinyl-3,6-dihydro-2H-pyridine-1-carboxylate. The latter reacted with maleic anhydride to form tert-butyl-(3aS,9bR)-1,3-dioxo-4,6,7,9,9a,9b-hexahydro-3aH-furo[3,4-h]isoquinoline-8-carboxylate as the Diels-Alder endo-adduct. Reactions of this adduct with electrophilic and nucleophilic reagents, as well as the reduction and oxidation of its functional groups was performed.