Modified coumarins. 26. Synthesis of angular dihydrooxazinocoumarins from 3-hydroxy[<Emphasis Type="Italic">b,d</Emphasis>]pyran-6-one

N-Substituted angular pyranodihydrobenzoxazines were prepared by condensation of 3-hydroxy-dibenzo[b,d]pyran-6-one with various primary amines and two equivalents of formaldehyde in the presence of 4-N,N-dimethylaminopyridine as base. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 14–17, January–February, 2007.     

Modified coumarins. 15. Condensed psoralen derivatives based on substituted dibenzo[<Emphasis Type="Italic">b,d</Emphasis>]pyran-6-ones

Benzo[c]furo[3,2-g]chromen-5-ones, modified psoralen analogs containing a substituted benzene ring annelated at the 5,6-position of the furo[3,2-g]chromen-7-one system, were prepared by the MacLeod method.Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 441–445, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Transformations of <Emphasis Type="Italic">ortho</Emphasis>-methoxyaryl(hetaryl)carboxamides into quinazolin-4-one and pyrido[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidin-4-one derivatives

ortho-Chloroaryl(hetaryl)carboxamides containing one or two nitro groups at positions 3 and/or 5 of the ring undergo condensation accompanied by the pyrimidine ring closure on refluxing in an excess of sodium methoxide to form bicyclic products, viz., quinazolin-4-one, pyrido[2,3-d]pyrimidin-4-one, and pyrido[4,3-d]pyrimidin-4-one derivatives. The scheme of cyclization processes was proposed. The structures of the reaction products were confirmed by a number of physicochemical data, including X-ray diffraction analysis. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1851–1858, August, 2005.     

Pyrano[4,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidinium salts

5-Aroyl-1,3,6-trimethyluracils were converted to pyrano[4,3-d]pyrimidinium salts. Reactions of the salts obtained with ammonia, primary amines, and hydrazine were studied. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2251–2257, November, 2007.     

Synthesis of pyrido[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidin-7(8<Emphasis Type="Italic">H</Emphasis>)-one derivatives from 5-acetyl-4-aminopyrimidines and β-dicarbonyl compounds

Heating of 5-acetyl-4-aminopyrimidine derivatives with ethyl acetoacetate, ethyl benzoylacetate, and diethyl acetone-1, 3-dicarboxylate in the absence of a base gave the corresponding 6-acylpyrido[2, 3-d]pyrimidin-7(8H)-ones. Under analogous conditions, the reaction with ethyl malonate afforded ethyl 7-oxo-7, 8-dihydropyrido[2, 3-d]pyrimidine-6-carboxylates. The pyridone (rather than hydroxypyridine) structures of the pyridopyrimidines obtained were confirmed by IR spectroscopy.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 770–773, March, 2005.     

Ionic Liquid Promoted One-Pot Synthesis of Furo[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidine-2,4(1<Emphasis Type="Italic">H</Emphasis>,3<Emphasis Type="Italic">H</Emphasis>)-diones

Summary. The three-component condensation of aldehyde, N,N′-dimethylbarbituric acid and alkyl or aryl isocyanide afforded the corresponding furo[2,3-d]pyrimidine-2,4(1H,3H)-diones in 1-butyl-3-methylimidazolium bromide as an ionic liquid in high yields at room temperature within several minutes.     

New method for the synthesis of thieno[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidines

The reaction of 5-formyl-4-thiocyanatopyrimidines with nitromethane was studied under various conditions. The reaction was found unexpectedly to proceed with closure of a thiophene ring to give thieno[2,3-d]pyrimidines. The use of ammonium acetate as the catalyst leads to a side reaction involving closure of an isothiazole ring to give isothiazolo[5,4-d]pyrimidines. X-ray diffraction crystallographic analysis was used to confirm the structure of thieno[2,3-d]pyrimidine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1564–1571, October, 2004.     

Synthesis of 8,8-R,R-8,9-dihydro[1,2,4]triazolo[1,5-<Emphasis Type="Italic">a</Emphasis>]quinazolin-6(7<Emphasis Type="Italic">H</Emphasis>)-ones

Three-component condensation of 3-amino-1,2,4-triazole (or its 5-methyl and 5-methylthio derivatives), dimedone (or cyclohexane-1,3-dione), and dimethylformamide dimethyl acetal afforded 8,8-R, R-8,9-dihydro[1,2,4]triazolo[1,5-a]quinazolin-6(7H)-ones. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2805–2807, December, 2005.     

Reaction of 2-methoxy-1,3,2-dioxaphosphorino[4,5-<Emphasis Type="Italic">b</Emphasis>]pyridin-4(4<Emphasis Type="Italic">H</Emphasis>)-one with hexafluoroacetone

The reaction of the di-O-trimethylsilyl derivative of 2-hydroxynicotinic acid with methyl phosphodichloridite afforded 2-methoxy-1,3,2-dioxaphosphorino[4,5-b]pyridin-4(4H )-one. The NMR spectrkscopic data suggest that the reaction of the latter with hexafluoroacetone produces unstable 2-methoxy-2,5-dioxo-4,4-bis(trifluoromethyl)-4,5-dihydro-1,3,2-dioxaphosphepino[4,5-b]pyridine, which is readily transformed into 9-methyl-2,5-dioxo-4,4- bis(trifluoromethyl)-4,5-dihydro-1,3,2-dioxaphosphepino[4,5-b]pyrid-9-inium-2-oate. The structure of the hydrolysis product of the latter, viz., 1-methyl-3-(2-hydroxy-3,3,3-trifluoro-2- trifluoromethylpropanoyl)pyridin-2-one, was established by X-ray diffraction analysis.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1640–1646, August, 2004.     

Synthesis and halogenation of allylthioethers of pyrazolo[3,4-<Emphasis Type="Italic">d</Emphasis>]pyrimidine

The interaction of 6-allylthio-4-imino-1-methyl-3-methylthio-5-phenyl-1,5-dihydro-4H-pyrazolo[3,4-d]-pyrimidine with bromine leads to the formation of 8-bromomethyl-4-imino-1-methyl-3-methylthio-5-phenyl-4,5,7,8-tetrahydro-1H-pyrazolo[4,3-e][1,3]thiazolo[3,2-a] pyrimidinium tribromide. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 602–604. April, 2007.     

Construction of a pyrido[4,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidine system on the basis of <Emphasis Type="Italic">N</Emphasis>-cyanobenzamidine and diethyl acetone-1,3-dicarboxylate

Nickel acetate promoted reaction of diethyl acetone-1,3-dicarboxylate with N-cyanobenzamidine led to ethyl 4-amino-6-ethoxycarbonylmethyl-2-phenylpyrimidine-5-carboxylate, upon treatment of which with RNH₂, the corresponding 6-(carbamoylmethyl)pyrimidines were obtained. Cyclization of the latter upon treatment with MeONa afforded 6-R-4-amino-7-hydroxy-2-phenylpyrido[4,3-d]pyrimidin-5(6H)-ones. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2212–2214, November, 2007.     

Xylogranatinin,a new pyrido[1, 2-<Emphasis Type="Italic">a</Emphasis>]pyrazine alkaloid from the fruit of a Chinese mangrove <Emphasis Type="Italic">Xylocarpus granatum</Emphasis>

9-Hydroxy-3-methoxy-6H-pyrido[1,2-a]pyrazin-6-one, a new pyrido[1,2-a]pyrazine alkaloid named xylogranatinin, was isolated from the fruit of a Chinese mangrove Xylocarpus granatum. Its structure was elucidated on the basis of spectroscopic data, especially 2D NMR techniques including HSQC and HMBC. To the best of our knowledge, this is the first time that a pyrido[1,2-a]pyrazine alkaloid was found as a natural product. Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 351–352, July–August, 2007.     

Pyrano[4,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidinium salts

Reactions of 5-aryl- and 5,7-diaryl-1,3-dimethyl-2,4-dioxopyrano[4,3-d]pyrimidinium salts with hydrazine were studied. In the former case, the reaction products were the 6-amino-1,3-dimethyl-2,4-dioxopyrido[4,3-d]pyrimidinium salts. 5,7-Diarylpyrano[4,3-d]pyrimidinium salts were transformed into either the corresponding pyridinium salts or 1H-pyrimido-[5,4-d][1,2]diazepine-2,4(3H,9H)-diones, depending on the hydrazine concentration and the reaction time. For Part 1, see Ref. 1. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1720–1725, May, 2008.     

Syntheses of 5,6-Diamino-1,3-Dihydrobenzo[<Emphasis Type="Italic">c</Emphasis>]thiophene 2,2-Dioxide

5,6-Diamino-1,3-dihydrobenzo[c]thiophene 2,2-dioxide was obtained by two methods from 5-amino-6-nitro- and 5-acylamino-1,3-dihydrobenzo[c]thiophene 2,2-dioxide.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 522–523, April, 2005.     

Synthesis and properties of a new fused heterocyclic system 12<Emphasis Type="Italic">H</Emphasis>-benzo[5,6][1,2,4]triazepino[3,4-<Emphasis Type="Italic">a</Emphasis>]isoindol-5(6<Emphasis Type="Italic">H</Emphasis>)-one

12H-Benzo[5,6][1,2,4]triazepino[3,4-a]isoindol-5(6H)-one was synthesized by the condensation of anthranilic acid hydrazide with o-phthalaldehyde. The structure of this compound was established by the X-ray diffraction study of its isopropyl derivative. The mechanism of formation of this compound was suggested and its alkylation reactions were investigated. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 180–185, January, 2008.     

Synthesis and reductive reactions of 2,3-dioxo-2,3-dihydrobenzo[<Emphasis Type="Italic">b</Emphasis>]furo[2,3-<Emphasis Type="Italic">f</Emphasis>]-, -[2,3-<Emphasis Type="Italic">g</Emphasis>]-, and -[3,2-<Emphasis Type="Italic">e</Emphasis>]indoles

The Sandmeyer reaction was used to prepare 2,3-dioxo-2,3-dihydrobenzo[b]furoindoles which could be reduced with diborane or with complex hydrides to give the corresponding unsubstituted as well as the 3-hydroxybenzo[b]furoindoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No 11, pp. 1683–1689, November, 2004.