A practical approach to imidazo[1,2]hetarylglyoxylates via Friedel-Crafts acylation of the parent fused imidazoles with ethyl oxalyl chloride is reported. The reaction is strongly influenced by the electron-donating properties of the starting heterocycle. The generated imidazo[1,2]hetarylglyoxylates undergo standard transformations typical of a-keto esters upon reaction with various nucleophiles. All the products contain an imidazoheterocyclic scaffold which is considered a privileged structure for drug discovery.

A convenient and efficient route for the chemoselective synthesis of carbohydrazide, arenesulfonylhydrazide, and thiosemicarbazone derivatives of 5H-pyrrolo[3,4-b]pyrazine and 1H-pyrrolo [3,4-b]quinoxaline from the corresponding dinitriles and substituted hydrazines was elaborated. The synthesis of starting pyrazine-2,3-dicarbonitrile was sufficiently improved by using concentrated HCl as a catalyst. pyrazine and 1H-Pyrrolo[3,4-b]quinoxaline 3377 © Georg Thieme Verlag Stuttgart · New York Synthesis 2013, 45, 3375-3382 O. V. Hordiyenko et al. PAPER Synthesis 2013, 45, 3375-3382 [3,4-b]quinoxalin-1-ylidene)carbohydrazides 4a-k; General Procedure Quinoxaline-2,3-dicarbonitrile (2; 0.63 g, 3.5 mmol) was dissolved by heating in anhydrous MeOH (30 mL) and the corresponding acid hydrazide (3.5 mmol) and NaOMe (0.35 mL, 1 N solution in MeOH) were added. The resulting mixture was refluxed with stirring for 4-6 h. After cooling, the precipitate formed was collected by filtration and washed with MeOH (5 mL). Recrystallization from MeOH, EtOH, or DMF afforded 4a-k. O. V. Hordiyenko et al. PAPER Synthesis 2013, 45, 3375-3382 PAPER 5H

Imidazo[1,2]hetarylglyoxylates: Synthesis and Reactivity Toward Nucleophiles. -The title compounds are synthesized via Friedel-Crafts acylation of fused imidazoles with ethyl oxalyl chloride. The products undergo standard transformations typical for α-keto esters. -(ZAMKOVA, I. A.; CHEKOTYLO, O. O.; GERASCHENKO, O. V.; GRYGORENKO*, O. O.; MYKHAILIUK, P. K.; TOLMACHEV, A. A.; Synthesis

Facile Synthesis of Hydrazine Derivatives of 5H-Pyrrolo[3,4-b]pyrazine and 1H-Pyrrolo[3,4-b]quinoxaline. -(HORDIYENKO*, O. V.; RUDENKO, I. V.; ZAMKOVA, I. A.; DENISENKO, O. V.; BIITSEVA, A. V.; ARRAULT, A.; TOLMACHEV, A. A.; Synthesis 45 (2013) 24, 3375-3382, http://dx.doi.org/10.1055/s-0033-1340042 ; Taras Shevchenko Natl. Univ., Kiev 01601, Ukraine; Eng.) -U. Scheffler 23-139