Nucleophilic substitution in 1-alkyl-4,5-dichloro-3-nitropyridazin-6-ones

Treatment of 1-alkyl-4,5-dichloro-3-nitropyridazin-6-one with C-nucleophiles and with ambident nucleophiles (2-azahetarylacetonitriles) leads to a selective substitution of a chorine atom by the quaternary carbon atom of the carbanion formed from a substituted acetonitrile. The pK_a of the CH-acid 2-(1-alkyl-5-chloro-3-nitro-6-oxo-1,6-dihydro-4-pyridazinyl)malononitrile was determined by potentiometric titration. Reaction of 2-(1-alkyl-5-chloro-3-nitro-6-oxo-1,6-dihydro-4-pyridazinyl)-2-hetarylacetonitriles with primary amines gives 6,7-dihydro-1H-pyrrolo[2,3-d]pyridazin-7-ones. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 556–564, April, 2006.     

Interaction of (1-phenylethyl)indole-2-carbonitrile with C-nucleophiles

Methods of obtaining ketones and enamino esters have been developed on the basis of reactions of 1-(1-phenylethyl)indole-2-carbonitrile with organomagnesium and organozinc compounds. Removal of a benzyl group from the indole nitrogen atom by the Grignard reagent has been discovered. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1179–1183, August, 2006.     

New versions of Pd0-catalyzed allylation of C-nucleophiles

New “one-pot” protocols proposed for Pd⁰-catalyzed allylation of C-nucleophiles involve deprotonation of the corresponding CH acids with in situ generated dialkylamide and alkoxide anions. Dedicated to Academician O. M. Nefedov on the occasion of his 75th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2024–2026, November, 2006.     

Mild addition of carbon nucleophiles to pyridine and quinoline N-oxides under different activation conditions

In the course of our syntheses of functionalised pyridine and quinoline derivatives, we examined the reactivities of pyridine and quinoline N-oxides towards the nucleophilic addition of acidic carbon derivatives. Different activating reagents were used, such as PyBroP, triflic anhydride and a combination of pyrrolidine phosphoramide and triflic anhydride.     

N-Polyfluoro(trimethylsilyl)ethyl azole derivatives

A facile synthetic route to N-polyfluoro(trimethylsilyl)ethyl azole derivatives was developed starting from N-bromo(chloro)polyfluoroethyl-substituted azoles. The silanes thus obtained were reacted with various electrophiles in the presence of the fluoride ion to yield the corresponding fluorinated carbinols, ketones, carboxylic acids, and methyl dithiocarboxylates as well as N-pentafluoroethylbenzimidazole.     

Transformations of C-adducts of 1,4-diazinium salts with dicarbonyl compounds into polycyclic systems

C-Adducts of 5-(het)aryl-2,3-dicyano-1-pyrazinium salts containing a residue of a 1,3-dicarbonyl compound at position 6 can be involved in the cyclization with hydrazine hydrate giving rise to pyrazino[2,3-c]pyridazines along with the expected pyrazole derivatives. The reactions of the same σ^H-adducts with hydroxylamine unexpectedly afforded triazacyclopenta[a]indene derivatives. The crystallographic data on the three-dimensional structures of new polycyclic compounds were obtained. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 639–643, March, 2008.     

Ring-opening reactions of oxetanes: A review of methodology development and synthetic applications

Ring-opening reactions of oxetanes yield important functionalized products depending upon the nature of nucleophiles as well as substitution pattern on the oxetane ring. Ring opening of oxetanes can be carried out under a variety of reaction conditions. In this review article, an up-to-date overview of major synthetic methodologies involved in the ring opening of oxetanes as well as their synthetic applications has been presented.     

Allylation of prochiral C-nucleophiles catalyzed by the Pd(0)—(<Emphasis Type="Italic">S</Emphasis>)-(—)-BINAP complex

The allylation of prochiral C-nucleophiles catalyzed by the Pd(0)—(S)-(—)-BINAP complex (BINAP is 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl) was studied. The enantioselectivity of the allylation was found to be low. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1753—1755, August, 2008.     

Reactions of 7-oxo(7-imino)-1,2,7,10-tetrahydro-1,10a-cyclohexano-2-R1-3-R2-4-R3-pyrido[1,2-a]benzimidazoles with C-nucleophiles and thioglycolic acid

Treatment of quinonemonoimines and an N-phenylquinonediimine of the pyrido[1,2-a]benzimidazole series with 1,3-indanedione, barbituric acid, or malononitrile and also with thioglycolic acid gives mono substitution at the 8 position. On the other hand, reaction of the N-cyclohexylquinonediimine in this series with C-nucleophiles leads to monosubstitution at position 9. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 403–410, March, 2006.     

Mono- and diadducts and bicyclic adducts in reactions of 2,3-dicyano-1-ethylpyrazinium cation with C- and O-nucleophiles

Products of diaddition of O- and C-nucleophiles to the 2,3-dicyano-1-ethylpyrazinium cation were isolated for the first time. The tandem A_N—A_N reactions of 2,3-dicyano-1-ethylpyrazinium tetrafluoroborate with 1,3-diketone enolates or keto esters afforded tetrahydrofuro[2,3-b]pyrazine derivatives, whereas cyclization with ethylene glycol gave tetrahydro-1,4-dioxino[2,3-b]pyrazine. Crystallographic data on the three-dimensional structures of these compounds were reported.