Intramolecular cyclization of 5-(o-carboxyphenyl)pyrrole derivatives

A new method is proposed for the synthesis of derivatives of indeno[1,2-b]-pyrrole-4-onesby intramolecular cyclization of the corresponding 5-(o-carboxyphenyl)pyrroles by trifluoroacetic anhydride.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1333–1335, October, 1987.     

A novel cyclization reaction of oxidodiazoalkanes: formation of pyrazoles and pyridazines

The thermal decomposition of dialkali metal salts of β- and γ-hydroxyketone tosyl-hydrazones in refluxing DME produced pyrazoles and pyridazines, respectively.     

The cyclization reaction of ortho-ethynylbenzaldehyde derivatives into isoquinoline derivatives

In order to elucidate the reaction mechanism of the cyclization between an ethynyl group and an imino group at the ortho-position on an aromatic ring to afford isoquinolines, reaction of 2-ethynylbenzaldehydes under various conditions was examined. It is concluded that reaction proceeds via an ionic process and the isoquinoline 4-hydrogen atom derives from the solvent. In addition, it was found that 2-ethynylbenzaldehyde O-methyloximes underwent cyclization in the presence of primary and secondary alcohols to give 3-substituted isoquinolines.     

A novel cyclization reaction of oxido diazoalkanes: formation of 1-substituted cycloalkenes

The thermal decomposition of dialkali metal salts of δ-hydroxybutyl ketone and ε-hydroxypentyl ketone tosylhydrazones in diglyme at 80–120 °C produced the 1-substituted cyclopentene and cyclohexene, respectively.     

Formation of 1,2-oxazine derivatives: A novel type of reaction between 2-aminooxazoles and maleic acid imide

N,N-Disubstituted 2-aminooxazoles in acetic acid at 20°C undergo addition of maleinimide, converting to alkylidene succinimides or 1,2-oxazine derivatives.N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913; e-mail: zhulin@cacr.ioc.ac.ru. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1128–1131, August, 2000.     

Synthesis of oxapenem derivatives by novel reductive cyclization

Several 6-ethyl-substituted l-oxapenem derivatives were synthesized by the application of the established method. Furthermore novel and effective synthesis of oxapenems $\text{via}$ reductive cyclization of 2-chloro-2-(4-chloro-3-ethyl-2-oxo-l-azetidinyl) acetoacetates ($\text{1}$$\text{0}$) using sodium thiolates is reported.     

Pummerer reaction of biotin sulfoxides : an access to new functionalized biotin derivatives.

Application of the Pummerer reaction to Biotin sulfoxides gives a good access to the corresponding thiolactol and thiolactone, which are key-compounds for the synthesis of new functionalized Biotin derivatives.     

A novel mesoionic ring system: unusual cyclization of thio- and amino-acid derivatives of 6-azauracil

Novel mesoionic heterocyclic structures 8 have been obtained via the internal cyclization of thio- and amino-acid derivatives of 6-azauracil 7b-d. These compounds undergo ring-opening reactions with amines to yield the respective 6-azauracil amides (9) in good yields under microwave irradiation.     

Formation of quinoacridinium system : A novel reaction of quinaldinium salts

N-Ethylquinaldinium salts heated in a solvent in the presence of a secondary amine yield 8,13-diethyl-6-methyl-8H-quino [4,3,2-de] acridinium salts. The structure of the iodide is determined by X-ray analysis. It is found that bond distances in quinoacridinium system are strongly affected by resonance interactions.     

A combined multicomponent-acid catalyzed cyclization reaction as an efficient route to novel tricyclic pyrrolo[2,1-a]isoquinoline derivatives

A simple, new two-step procedure for the synthesis of novel tricyclic pyrrolo[2,1-a]isoquinoline derivatives is described. The initially prepared polysubstituted pyrroles obtained via the four-component condensation of arylglyoxals, cyclic 1,3-dicarbonyls, aminoacetaldehyde dimethyl acetal, and β-keto esters subsequently underwent intramolecular acid-catalyzed cyclization to the desired products in moderate to good yields.     

Formation of benzofuran and 2H-chromene structures in one reaction. A novel synthesis of 2H-chromene derivatives

Heating the morpholinal of nitrosalicylic aldehyde with methyl propiolate in acetonitrile in the presence of Cul affords an equimolar mixture of 2-methoxycarbonylmethyl-3-morpholino-5-nitrobenzofuran and 3-methoxycarbonyl-2-morpholino-6-nitro-2H-chromene, the structures of which were determined by X-ray analysis. Only the 2H-chromene mentioned above was obtained in the absence of Cul and solvent.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1222–1228, May, 1996.     

Stereoselection in radical cyclization of beta-alkoxyvinyl sulfoxides: synthesis of tetrahydrofuranyl allyl carbinols

[reaction: see text] Tetrahydrofuranyl allyl carbinols may be prepared stereoselectively via radical cyclization of beta-alkoxyvinyl sulfoxides, Pummerer rearrangement, and reaction with allylstannane.     

A new entry to oxacycles via base-catalyzed endo mode cyclization of allenyl sulfoxides and sulfones

[reaction: see text]. Treatment of the allenyl sulfoxides and sulfones possessing a proper delta-hydroxy appendage at the C-1 position with potassium tert-butoxide effected endo mode ring closure at the sp-hybridized carbon center of the allenyl moiety to provide the five- to eight-membered oxacycles in high yields.     

Cross-metathesis reaction of vinyl sulfones and sulfoxides

Cross-metathesis reactions of α,β-unsaturated sulfones and sulfoxides in the presence of molybdenum and ruthenium pre-catalysts were tested. A selective metahesis reaction was achieved between functionalized terminal olefins and vinyl sulfones by using the ‘second generation’ ruthenium catalysts 1c-h while the highly active Schrock catalyst 1b was found to be functional group incompatible with vinyl sulfones. The cross-metathesis products were isolated in good yields with an excellent (E)-selectivity. Both the molybdenum and ruthenium-based complexes were, however, incompatible with α,β- and β,γ-unsaturated sulfoxides.     

A novel reaction in ionic liquids: selective cyclization of 1-dodecene to cyclododecane under moderate pressure

A novel reaction of cyclization of 1-dodecene to cyclododecane with high selectivity, especially under moderate pressure, is found in ethanol buffered chloroaluminate ionic liquids with easy separation of product duo to the immiscibility with ionic liquids.