Heterocycles. Part I. A new route to the synthesis of substituted 2-aminopyrimidines

Heterocyclic aldehydes (A) reacted with alkyl aryl ketones (B) to give the corresponding 1,3-diaryl-2-propen-1-ones (Ia-1). Condensation of these chalcones with guanidine produced the corresponding 2-amino-4,6-diarylpyrimidines (IIa-1). The structure of all products was substantiated by chemical and spectroscopic methods.     

A new route for the synthesis of 1,3-diketones

A simple route for the synthesis of 1,3-diketones by the reaction of acetylenic ketones with amines followed by hydrolysis of the resulting aminovinylketons is suggested.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 710–714, April, 1995.     

A novel synthesis for new substituted imidazoles

The addition of dimethyl acethylendicarboxylate (DMAD) to thiosemicarbazone and guanylhydrazone of aldehydes afforded compoundes which were characterized to be new substituted imidazoles. Their structures were determined by ¹H NMR, IR, mass spectra and elemental analyses.     

A new route for the synthesis of phenazine di-N-oxides

Summary Several phenazine 5,10-dioxides (7a–d) were prepared by the reaction of 2-methyl-3-acetylquinoxaline 1,4-dioxide (2) with different aromatic aldehydes or by direct cyclization of the quinoxaline cinnamoyl derivatives3 in basic medium. In addition, the phenazine derivatives8 and9–12 were synthesized by a one-pot reaction of substitutedo-nitroanilines with different hydroxy compounds in the presence of sodium hypochlorite solution.

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Ein neuer Syntheseweg für Phenazin-di-N-oxide

Zusammenfassung Mehrere Phenazin-5,10-dioxide (7a–d) wurden durch Reaktion von 2-Methyl-3-acetylchinoxalin-1,4-dioxid (2) mit verschiedenen aromatischen Aldehyden oder durch direkte Cyclisierung der Chinoxalinderivate3 in basischem Milieuhergestellt. Zusätzlich wurden die Phenazinderivate8 und9–12 in einer Eintopfreaktion von substituierteno-Nitroanilinen mit verschiedenen Hydroxyverbindungen in Gegenwart von Natriumhypochloritlösung synthetisiert.

     

A new route to fullerene substituted phenylalanine derivatives

A series of fullerene substituted phenylalanine derivatives have been prepared by the condensation of 1,2-(4'-oxocyclohexano)fullerene with ester or Boc protected (4-amino)phenylalanine, H(2)NC(6)H(4)CH(2)CH(COR(1))(NHCOR(2))(where R(1) = OMe, R(2) = Me; R(1) = OH, R(2) = Me, O(t)Bu). Conversion of the imine to the corresponding amine is achieved by di-acid catalyzed hydroboration. Reaction of the N-Ac amino ester with BBr(3) led to the formation of the parent amino acid, while the Boc-protected derivative readily undergoes coupling with NH(2)-Gly-OEt. The reduction of the imine is not accompanied by hydroboration of the fullerene cage.     

A new asymmetric synthetic route to substituted piperidines

An asymmetric synthesis of substituted piperidines has been described. β-Cyclodextrin- or oxazaborolidine-catalyzed asymmetric reduction of α-azido aryl ketones to the corresponding alcohols has been employed as the key step along with ring closing metathesis and selective dihydroxylation.     

A conventional route for the synthesis of new oxazolidin-2-one derivatives with beta-aminoalanines

A conventional new route to the novel oxazolidin-2-one derivatives (3a-f) having two substituents on N-3 and C-4 in the oxazolidin-2-one ring was established with racemic beta-aminoalanine derivatives (1) as the key starting materials.     

A new route for the synthesis of 10-hydroxydec-2E-enoic and dec-2E-enedioic acids

A new simple route for the synthesis of 10-hydroxydec-2E-enoic and dec-2E-enedioic acids from cycloocta-1Z,5Z-diene has been developed.Institute of Chemistry, Bashkir Branch, Academy of Sciences of the USSR, Ufa. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 695–698, November–December, 1983.     

A new synthesis of unsymmetrically substituted halophosphines

Chiral, racemic alkylaryl-, or diarylhalophosphines have been obtained in 50–70% yields by treatment of alkylaryl- or diaryl-methylthiohalophosphonium triflates with triphenylphosphine in methylene chloride solution at room temperature or under reflux.     

A new synthesis of substituted 2(1H)-pyrazinones

The hydrohalides of 2-sec-aminoalkanenitriles on treatment with oxalyl halides in o-dichlorobenzene at 80-100° give 3, 5-dihalo-2(1H)-pyrazinones, of which the 3-halo substituent is easily replaced by nucleophiles. A reaction mechanism for the pyrazinone synthesis is proposed.     

A new synthesis of substituted 1,4,5,6-tetrahydropyridines

3-Ethoxycarbonyl- and 3-acetyl-4-cyano-2,4, 6, 6-tetramethyl-1, 4, 5, 6-tetrahydropyridines have been obtained by the reaction of diacetoneamine with acetoacetic ester (or acetylacetone), the conversion of the amino ketones so obtained into the corresponding cyanohydrins, and the cyclization of the latter under the influence of alkali.     

A new synthetic route to substituted 1-fluoro-1-cyclopropanecarboxylates

Substituted 6-fluoro-2,4-dioxo-3-azabicyclo[3.1.0]hexane-6-carboxylates were obtained as a mixture of the exo- and endo-isomers by reaction of substituted 6,8-dioxo-2,3,7-triazabicyclo[3.3.0]oct-3-en-4-carboxylates with N-fluoropyridinium tetrafluoroborate.     

Novel synthesis of the ocular age pigment A2-E: new method for substituted pyridine synthesis via azaelectrocyclization

[reaction: see text] The formal synthesis of the ocular age pigment A2-E was achieved by the efficient one-pot preparation of the substituted pyridine, which involves the aza-6pi-electrocyclization of the Schiff base derived from (E)-3-carbonyl-2,4,6-trienal followed by oxidation.     

A new synthesis of functionally,substituted hydroquinones

Functionally substituted organoboranes readily react with p-benzoquinone yielding the corresponding functionally substituted hydroquinones in essentially quantitative yields.     

A new catalytic route to synthesis of silylgermylethynes

Silylgermylethynes known to be potential organometallic reagents and precursors of optoelectronic materials can be efficiently synthesized via a recently reported catalytic method called silylative coupling of alkynes with vinylsilicon compounds. The reaction of triethylethynylgermane with vinyltrisubstituted silanes catalyzed by [RuHCl(CO)(PR₃)_n] (where R = ⁱPr, Cy, Ph; n = 2-3) under optimal conditions selectively yields respective silylgermylethynes. Silylation of ethynylgermane with divinylsilicon derivatives such as siloxanes, silazanes, bis(silyl)benzene and bis(silyl)ethane gives monoethynylgermyl substituted vinyldisilicon products with high yields and selectivity, however, accompanied by traces of dialkynylgermyl derivatives. All catalytic results as well as those of stoichiometric study on the insertion of ethynylgermane into Ru-Si bond have permitted proposing mechanistic schemes of the reaction examined.     

A new approach to the synthesis of substituted 2(1H)-quinolinones

A new synthetic approach for the preparation of substituted 2(1H)-quinolinones 5 from readily available anilines has been developed. The four step procedure resulted in the synthesis of a variety of substituted 2(1H)-quinolinones in good yields and under mild reaction conditions.