[reaction: see text] The one-pot synthesis of new 9-alkyl-6-chloropyrido[3,2-e][1,2,4]triazolo[4,3-a]pyrazines has been achieved. Hydrazides regioselectively reacted as nucleophiles with the 3-chloro substituent of 2,3-dichloropyrido[2,3-b]pyrazine. An intramolecular cyclization afforded the tricycle nonxanthine adenosine receptor antagonists.

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Synthesis of 9-Alkyl-6-amino[1,2,4]triazolo[3,4-c]-5-azaquinoxalines. Mild and Effective SNAr Amination of Highly Electron-Poor Heterocycles. -The previously reported substrates (I) readily undergo an SNAr reaction with ammonia in acetonitrile solution under thermal or microwave conditions. -(UNCITI-BROCETA*, A.; PINEDA-DE-LAS-INFANTAS, M. J.; GALLO, M. A.; ESPINOSA, A.; Tetrahedron Lett. 51 (

Pyrazine derivatives R 0550Regioselective One-Pot Synthesis of 9-Alkyl-6-chloropyrido[3,2-e][1,2,4]triazolo[4,3-a]pyrazines. Reactivity of Aliphatic and Aromatic Hydrazides. -A new method to prepare the title pyrazines is reported. However, the reaction with aromatic hydrazides and electron-withdrawing substituted aliphatic hydrazides results in formation of keto analogues such as (VI) and (VIII). In the presence of an excess of hydrazide, tetracyclic systems like (IV) are obtained. -(UNCITI-BROCETA, A.; PINEDA-DE-LAS-INFANTAS, M. J.; DIAZ-MOCHON, J. J.; ROMAGNOLI, R.; BARALDI, P. G.; GALLO, M. A.; ESPINOSA*, A.; J.