Pyrrolo[2,1-b]benzothiazole derivatives

A new method for obtaining pyrrolobenzothiazole derivatives, which can be used for the specific synthesis of polymethine dyes with predesignated properties, was developed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 549–553, April, 1991.     

Some derivatives of indeno[2,1-g]pteridine

The condensation of indantrione monohydrate (ninhydrin) with ortho-diamines derived from pyridine and pyrimidine led to the synthesis of several new indeno[2,1-g]pteridine derivatives. The structure of these compounds is discussed and their physical properties described.     

Synthesis of new hetero[2,1]benzothiazepine derivatives

As part of an investigation directed to the search of new neurotropic agents we have prepared a number of hydroxy and hydroximino derivatives of the novel thieno and pyrazolo[2,1]benzothiazepine ring systems. Assignments of the Z and E hydroximino isomers were performed by study of their ¹H and ¹³C nmr spectra and NOE experiments.     

Synthesis of 2,3,3a,8a-tetrahydroindeno[2,1-b]pyrrole derivatives

A new entry into the 2,3,3a,8a-tetrahydroindeno[2,1-b]pyrrole system, 1 , has been investigated. 2,3,3a,8a-Tetrahydro-3a,8a-dihydroxy-1-methylindeno[2,1–6]pyrrole-2,8-dione, 3 , formed from the reaction of ninhydrin and N-methylacetamide has been subjected to catalytic hydrogenation, hydride reduction, and chlorination reactions to afford a variety of substituted derivatives of 1 .     

Synthesis of derivatives of the new heterocyclic systems benz[f] imidazo [2,1 -a ] isoquinoline and benz [f] pyrimido [2,1 -a] isoquinoline

The synthesis of several derivatives of benz [f] imidazo [2,1 -a] isoquinoline and benz [f] pyrimido-[2,l-a]isoquinoline, both new heterocyclic structures, is described.     

Synthesis of pyrido [2,1-f]-1,3,4-oxadiazine derivatives

A convenient synthesis of derivatives of the 4H-pyrido [2,1-b]-1,3,4-oxadiazine ring system from readily available 1-amino-4,6-diphenyl-2-pyridone and phenacyl bromides or arylmethyl ketones is described.     

Construction of benzo[d]imidazo[2,1-b]thiazole derivatives via a simple multi-component domino cyclization

Research on Chemical Intermediates - An operationally simple and highly efficient one-pot multi-component domino cyclization for the preparation of benzo[d]imidazo[2,1-b]thiazole derivatives from...     

Carbazolo[2,1‐a]carbazole derivatives via fischer indole synthesis

A series of new carbazolo[2,1‐a]carbazoles was synthesized from 4‐oxo‐1,2,3,4‐tetrahydrobenzo[a]‐carbazole derivatives.     

Research on heterocyclic compounds. XXI. Synthesis of imidazo[2,1-b]benzothiazole and imidazo[2,1-b]thiazole derivatives

The reaction of some 2-aminobenzothiazoles and 2-aminothiazoles with ethyl 3-bromo-4-oxopentanoate was investigated with the aim to obtain the corresponding imidazo[2,1-b]benzothiazole and imidazo[2,1-b]-thiazole derivatives, respectively. In some cases, two unexpected side products were obtained together with the required compound and their structures were elucidated: e.g., 2-aminobenzothiazole reacted with ethyl 3-bromo-4-oxopentanoate to give ethyl 2-methylimidazo[2,1-b]benzothiazole-3-acetate together with ethyl imi-dazo[2,1-b]benzothiazole-2-propionate and ethyl 3-(benzothiazol-2-yl)amino-4-oxopentanoate.     

Mass spectra of imidazo[2,1-b]thiazole and thiazolo[3,2-f]xanthene derivatives

The general principles of the mass-spectrometric disintegration of imidazo [2,1-b]thiazole and thiazolo[3,2-f]xanthene derivatives were established, and the characteristic fragments were identified. Disintegration proceeding with cleavage of the bonds in the thiazole ring of the 2(3)-ring system is characteristic of all of the investigated compounds. The cleavage of the S-C bonds, which are the weakest in the investigated systems, proceeds especially readily. Intense peaks of ions due to stepwise disintegration of the pyrimidine ring are also observed in the spectra of thiazoloxanthenes.     

Synthesis of pyrrolo[2,1-b]oxazole derivatives (microreview)

Chemistry of Heterocyclic Compounds - This review provides generalized information on the synthesis of substituted pyrrolo[2,1-b]oxazoles, including derivatives fused with other rings, covering...     

Reduction of nitro derivatives of azolo[5,1-c][1,2,4]triazines

Reduction of6-nitro-7-oxo-4,7-dihydroazolo[5,1-c][1,2,4]triazines into the corresponding amines with sodium dithionite takes place smoothly in neutral aqueous solutions. The structural effects in reduction of nitroazoloazines were evaluated electrochemically.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 674–677, May, 1992.     

Acyliminium ion-olefin cyclization leading to isoindolo[2,1-a]quinoline derivatives

Isoindolo[2,1-a]quinolines 10 , 11 , 12 were synthesized from hydroxylactams 8 or 9 via an N-acyliminium ion-π-olefin nucleophile cyclization reaction.