Reaction of 4-methyl-5,6-dihydro-2h- and 4-methylenetetrahydropyrans with phenylsulfinyl chloride

4-Methyl-5,6-dihydro-2H- and 4-methylenetetrahydropyrans undergo an ene- type reaction with phenylsulfinyl chloride in the presence of ZnCl₂ to give the corresponding allylic sulfoxides.October Revolution Fortieth Anniversary, Bashkir State University, UfaTranslated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1446–1447, June, 1990.     

Basicities and structures of 4,4,6-trimethyl-2-arylamino-5,6-dihydro-4H-1,3-thiazines and 4,4,6-trimethyl-2-arylamino-5,6-dihydro-4H-1,3-oxazines

The relative basicities of 4,4,6-trimethyl-2-arylamino-5,6-dihydro-4H-1,3-thiazines and 4,4,6-trimethyl-2-arylamino-5, 6-dihydro-4H-1,3-oxazines, which are capable of amine-imine tautomerism, and of model compounds with fixed amine and imine structures were determined by potentiometric titration in methanol. Good correlation of the pK _a values with the Hammett constants in the investigated reaction series was found. The inapplicability of the use of the pK _a values of model compounds for the determination of the tautomeric equilibrium constants in the case of some N-heterocyclic amines of nonaromatic character with an aryl substituent attached to the exocyclic nitrogen atom of the amidine fragment of the molecule is demonstrated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1621–1624, December, 1976.     

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.     

structure of 4,4,6-trimethyl-2-mylamino-5,6-dihydro-4H-1,3-thiazines and -oxazines

It is shown by means of IR, PMR, and UV spectra that 4,4,6-trimethyl-2-arylamino-5, 6-dihydro-4H-1,3-thlazines and 4,4,6-trimethyl-2-arylamino-5,6-dihydro-4H-1,3-oxazines in the crystalline state and in solution exist primarily in the amino form. It was found that ionization to give cations proceeds more readily in the case of 1,3-oxazines than in the case of 1,3-thiazines. In addition, a decrease in the ability to undergo intermolecular association and a decrease in the energy barrier to rotation about the N-heteroring bond are observed for 1,3-oxazines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 346–352, March, 1977.     

Notiz zur Darstellung von 4-Hydroxy-6-methyl-5,6-dihydro-2H-pyran-2-on

Meldrum's acid (2) is acylated by diketen affording the acylMeldrum's acid3. In aqueous bicarbonate its 3-oxogroup is selectively reduced by sodium tetrahydroborate giving the alcohol4, which readily undergoes cyclization in refluxing dioxane leading to the title pyrone7. Under identical conditions3 produces the pyrone6 with the pyrone carboxylic acid5 as intermediate.

     

Synthesis of substituted 2-amino-5,6-dihydro-4H-1,3-thiazines and 2-iminotetrahydro-1,3-thiazines

N-Aryl-N′-(2-methyl-4-hydroxy-2-pentyl)thioureas are cyclized in acidic media to 4,4,6-trimethyl-2-arylimino-5,6-dihydro-4H-1,3-thiazines, the methylation of which with methyl iodide gives 4,4,6-trimethyl-2-methylarylamino-5,6-dihydro-4H-1,3-thiazines. 3,4,4,6-Tetramethyl-2-aryliminotetrahydro-1,3-thiazines were synthesized by cyclization of Naryl-N′-methyl-N′-(2-methyl-4-hydroxy-2-pentyl)thioureas.     

Synthesis and study of NOS-inhibiting activity of 2-N-acylamino-5,6-dihydro-4H-1,3-thiazine

The synthesis and results of in vitro and in vivo testing of 2-N-acetylamino-, 2-N-benzoylamino-,2-N-cyclohexanecarbonylamino-, and 2-N-(1-adamantanecarbonyl)amino-5,6-dihydro-4H-1,3-thiazines for NOS-inhibiting activity have been described.     

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 crystal structure of 4-acetoxy-5,6-dihydro-5,5-dinitro-2H-1,3-oxazineN-oxide

A novel heterocyclic compound, 4-acetoxy-5,6-dihydro-5,5-dinitro-2H-1,3-oxazineN-oxide, has been synthesized by the reaction of the dipotassium salt of 1,1,5,5-tetranitro-3-oxapentane with aqueous acetic acid. The synthesized compound has been studied by X-ray diffraction analysis.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2207–2210, December, 1994.We would like to thank G. V. Lagodzinskaya (Institute of Chemical Physics in Chernogolovka, Russian Academy of Sciences) for recording and interpreting¹H NMR spectra, A. M. Korolev (Institute of Chemical Physics in Chernogolovka, Russian Academy of Sciences) for helpful discussion, and V. I. Fetisov (Institute of Physiologically Active Compounds, Russian Academy of Sciences) for performing quantum-chemical calculations by the AM1 SCF MO LCAO method.     

Cleavage of 2-methyl-5,6-dihydro-2h-pyrane by acid halides

The reaction of 2-methyl-5,6-dihydro-2H-pyrane with a number of acid halides in which the ring is cleaved is accompanied by an allylic rearrangement. The halogen atom in the isomers is replaced in the usual way by nucleophilic reagents, but aqueous alkali causes in addition the formation of 1,3,5-hexatriene and to a lesser extent recyclization to dihydropyrane.Translated from Khimiya Geterotsikhicheskikh Soedinenii, No. 12, pp. 1600–1602, December, 1984.     

Mass-spectrometric study of 5,6-dihydro-4H-1,3-oxazin-5-ones

Under the influence of electron impact, 2-aryl-1,3-oxazin-5-ones undergo fragmentation primarily with the elimination of the C₂H₂O₂ group of atoms, as well as with the formation of aroyl cations. The complete absence of the retrodiene fragmentation that is characteristic for such heterocyclic systems makes it possible to conclude that the double bond in the heteroring is not stabilized. In the case of 4-alkyl- and 4-benzyl-substituted oxazinones the molecular ions under-go rearrangement, as a result of which a seven-membered heteroring is formed due to inclusion of the methylene group of the substituent in an oxazine ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 43–47, January, 1981.     

Synthesis,steric structure,and biological activity of 5-methyl-2-(morpholin-4-ylamino)-5,6-dihydro-4H-1,3-thiazin-4-one

Russian Journal of General Chemistry - New 5,6-dihydro-1,3-thiazin-4-one derivatives have been synthesized by one-pot reaction of morpholin-4-amine and adamantan-1-amine with methacryloyl...     

Synthesis and Structure of Quaternary Salts Derived from 2-Anilino- and 2-Benzylamino-5,6-dihydro-4H-1,3-thiazine

Substituted phenacyl bromides react with 2-anilino-5,6-dihydro-4H-1,3-thiazine at the exocyclic nitrogen atom and with 2-benzylamino-5,6-dihydro-4H-1,3-thiazine at the nitrogen atom in the ring. The structure of the reaction intermediates was elucidated, and their cyclization into 1-benzyl-2-aryl-6,7-dihydro-5H-imidazo[2,1-b][1,3]thiazinium bromides was performed.     

Synthesis of nitro-substituted 4-methyl-2,3-dihydro- and 2,3,4,5-tetrahydro-1H-1,5-benzo-2-diazepinones

The nitration of 4-methyl-2,3-dihydro-1H-1,5-benzo-2-diazepinone gives the 7 nitro derivative. The 8-nitro isomer was obtained from 4-nitro-1,2-phenylenediamine. The catalytic hydrogenation of the nitrobenzodiazepinones gives the 7- and 8-amino derivatives. The nitrobenzodiazepinones exist in the enol form in alkaline media.     

Nitration of 4-methyl-5,6-dihydro-2H-pyran and some aspects of the preparation and isomerization of nitrodihydropyrans

The reaction of 4-methyl-5,6-dihydro-2H-pyran with acetyl nitrate to give additive and substitutive nitration products has been examined. It is shown that the addition product, 4-acetoxy-4-methyl-3-nitro-tetrahydropyran, is deacylated on treatment with bases to give an ,-unsaturated nitro-compound which isomerizes under the reaction conditions to a ,-unsaturated nitro-compound. 4-Acetoxy-4-nitromethyltetrahydropyran behaves similarly.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 305–308, March, 1987.