4 + 2]-Cycloaddition Reactions between beta-Acceptor-Substituted Enamines and 2-Vinylindole Radical Cations Acting as Hetero-Dienes

[4 + 2]-Cycloaddition reactions between 2-vinylindoles acting as hetero-dienes and beta-acceptor substituted cyclic and acyclic enamines can be induced by formation of 2-vinylindole radical cations either via anodic oxidation or photoelectron transfer (PET) using catalytic amounts of triarylpyrylium tetrafluoroborates as sensitizers. In this way, pyrido[1,2-a]indoles or indolo[1,2-a]hexahydro-1,8-naphthyridines are formed in one step with complete regio- and stereochemical control.     

Reactions of 2-sulfanylethanol with mucochloric acid and its derivatives

Mucochloric acid reacted with 2-sulfanylethanol in the presence of triethylamine to give 3-chloro-5-hydroxy-4-(2-hydroxyethylsulfanyl)furan-2(5H)-one which underwent acid-catalyzed cyclization to 7-chloro-2,3,4a,6-tetrahydrofuro[2,3-b][1,4]oxathiin-6-one. Likewise, reactions of 5-alkoxy-3,4-dichlorofuran-2(5H)-ones with 2-sulfanylethanol in the presence of triethylamine involved replacement of chlorine in position 4 of the furan ring with formation of the corresponding 4-(2-hydroxyethylsulfanyl) derivatives. The reaction of mucochloric acid with 2-sulfanylethanol in excess aqueous potassium hydroxide resulted in the formation of an acyclic product, 3-(2-hydroxyethylsulfanyl)-2-chloroprop-2-enoic acid. The structure of 7-chloro-2,3,4a,6-tetrahydrofuro[2,3-b][1,4]oxathiin-6-one and 3-(2-hydroxyethylsulfanyl)-2-chloroprop-2-enoic acid was proved by X-ray analysis.     

Reactions of 2-Pyrones with 7-Aminoindazole: The First Synthesis of N-(1H-7-Indazolyl)-pyridinones

New N-(1H-7-indazolyl)-pyridinones have been prepared by the condensation of 2-pyrone derivatives with 7-aminoindazole in the presence of acid medium. They have been characterized by means of ¹H and ¹³C NMR, IR, and mass spectroscopy. The structure of the compounds and the mechanism of their formation are reported.     

The First Cyclopentadienylalkylphosphane Nickel Chelates: Synthesis,Structures, and Reactions

The first cyclopentadienylalkylphosphane nickel chelate complexes are reported. The anionic ligand obtained by reaction of spiro[2.4]hepta‐4,6‐diene with lithium di‐tert‐butylphosphide was treated with NiCl₂ to yield [η⁵:κ¹‐(di‐tert‐butylphosphanylethyl)cyclopentadienyl]chloronickel(II). From this complex, some acetonitrile‐stabilized cationic complexes were obtained by reaction with the respective silver salts in acetonitrile. Methyl‐ and alkynylnickel chelates were prepared by reaction of the chloronickel complex with methyllithium and by copper‐mediated coupling with terminal alkynes, respectively. Some of the complexes prepared were investigated by X‐ray crystallography or cyclic voltammetry. The alkynylnickel chelates undergo cycloaddition reactions with ethoxycarbonylisothiocyanate or tetracyanoethylene, and the cyclobutenes obtained undergo ring opening to the corresponding dienes. The study includes an NMR spectroscopic investigation of the two conformers of one of these dienes.     

Reactions of 2-mercaptoacetic acid with mucochloric acid and its derivatives

The stable products of reactions of mucochloric acid and some of its ethers with 2-mer-captoacetic acid were synthesized and characterized. The variation of experimental conditions allowed targeted introduction of a sulfur- containing fragment into particular position of the heterocycle: the reaction in aqueous potassium hydroxide gives 3-substituted 2(5H)-furanone the triethylamine additive in nonaqueous solvents facilitates the formation of 4-substituted products, and acid catalysis results in the replacement of the hydroxy (methoxy) group at C(5). (3,4-Dichloro-2-oxo-2,5-dihydrofuran-5-ylthio)ethanoic acid and (3-chloro-5-hydroxy-2oxo-2,5dihydrofuran-4-ylthio)ethanoic acid were characterized by X-ray diffraction; their crystal and gas-phase structures were discussed. The 5-monosubstituted product crystallizes as a racemate, while 4monosubstituted product, as a conglomerate.     

Synthesis and properties of N-aminoazolinethiones and N-aminoazinethiones 2. Reactions

Literature data on the reactivity of -mercapto derivatives of N-aminoazoles and N-aminoazines are reviewed.For Part 1 see [1].Rostov State University, Rostov-on-Don 344090. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1155–1181, September, 1997.     

Synthesis of Sulfides by Reactions of 1,1-Dichloro-2-chloro-methylcyclopropane with S-Nucleophiles

1,1-Dichloro-2-chloromethylcyclopropane reacts with thiolates to give 2,2-dichlorocyclopropylmethyl sulfides via replacement of the side-chain chlorine atom. The resulting sulfides are readily oxidized to the corresponding sulfones.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 3, 2005, pp. 381–386.Original Russian Text Copyright © 2005 by Mikhed’kina, Nedel’ko, Prezhdo.     

Reactions of monothiooxamides with N-nucleophiles. Synthesis of 4,5-dihydroimidazole-2-carboxanilides

A convenient procedure was developed for the preparation of 4,5-dihydroimidazole-2-carboxanilides by the reaction of monothiooxamides with ethylenediamine. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 753–757, April, 1999.     

Synthesis of fluorine-containing alkyl 2-cyano-3-oxocarboxylates. Reactions with nucleophiles

Fluorine-containing alkyl 2-cyano-3-oxocarboxylates were synthesized for the first time by the reaction of ethyl cyanoacetate with fluorine-substituted carboxylic acid halides or alkyl carboxylates. The reactions with hydrazine hydrate, phenylhydrazine, ando-phenylenediamine give hydrazinium (ammonium) enolates or products of acid decomposition. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1961–1965, October, 1999.     

Synthesis and Reactions of 3-Halogenated 2-CF3-Indoles

Halogenation of 2-trifluoromethylindole afforded 3-chloro-, 3-bromo- and 3-iodo derivatives in up to 98% yield. Methyl-, benzyl- and tosyl-groups can be installed at the nitrogen atom of prepared indoles in high yields by base catalyzed reaction with the corresponding alkylating (sulfonylating) reagents. A high synthetic utility of the prepared haloindoles in the reaction with various nucleophilies was shown. The reaction with 4-methylthiophenol and copper cyanide afforded the corresponding sulfides and nitriles in high yield. Palladium catalyzed cross-coupling with phenyl boronic acid and phenylacetylene gave the corresponding 3-phenyl-2-CF₃-indoles and acetylenic derivatives in 72–98% yield.     

Reactions of 5-methylene-1,3-dioxolan-2-ones with amines. Synthesis of 2-oxazolidinones

The reaction of 5-methylene-1,3-dioxolan-2-ones with aromatic or aliphatic amines as well as with the sodium salts of amino acids leads to 4-hydroxy-2-oxazolidinones. The reaction conditions depend on the basicity of the amines. The use of o-phenylenediamine in this reaction leads to the formation of a new heterocyclic system.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow; Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 241–251, February, 1999.     

Reactions of 2-Arylhydrazonoacetamides with Orthoesters. Synthesis of New Tetrahydro-1,2,4-triazines

The reactions of arylhydrazonocyanoacetamides with triethyl orthoformate and triethyl orthoacetate have been studied. Interaction of triethyl orthoformate with amides bearing normal alkyl substituents on the carbamoyl group resulted in cyclization to 2-aryl-4-alkyl-5-oxo-3-ethoxy-2,3,4,5-tetrahydro-1,2,4-triazin-6-carbonitriles, whereas reaction of N-phenyl- and N-cycloalkylacetamides with triethyl orthoformate gave products of ethylation at the hydrazone group. Reactions of arylhydrazonocyanoacetamides with triethyl orthoacetate led to 2-(arylethylhydrazono)acetamides exclusively.