par Martin, Richard ;Tarasiejska, Zofia
Référence Bulletin des Sociétés chimiques belges, 66, 1, page (136-150)
Publication Publié, 1957
Article révisé par les pairs
Résumé : a) 5,6‐diphenylimidazo [4,5‐b] pyrazine (VIIIa), 2‐methyl‐5,6‐diphenylimidazo [4,5‐b] pyrazine (VIIIb) and 2‐hydroxy‐5,6‐diphenylimidazo [4,5‐b] pyrazine (VIIIc) have been prepared by treatment of 2,3‐diamino‐5,6‐diphenylpyrazine (VII) with ethyl formate, acetic anhydride and urea respectively. The diamine (VII) was obtained as follows: 1°) 2‐hydroxy‐3‐nitro‐5,6‐diphenylpyrazine (V) + POCl3 (or PBr3) (or PBr3) → 2,3‐dichloro‐(or dibromo‐)‐5,6‐diphenylpyrazine (VIb) (or VIc) [also VIb + PBr3 → Vlc], 2°) Vlb (or VIc) + NH3 → 2,3‐diamino‐5,6‐diphenylpyrazine (VII). When (V) was heated with POCl3, 2‐chloro‐3‐hydroxy‐5,6‐diphenylpyrazine (VIa) was also formed. b) 5,6‐diphenylimidazolino [1,2‐a] pyrazine (XV), a representative of a new cyclic system, has been synthesized by the following scheme: 1°) 2‐bromo‐(or 2‐chloro‐ or 2‐mercapto‐)‐5,6‐diphenylpyrazine (XII) + NH2‐CH2‐CH2OH → 2‐(2‐hydroxyethyl) amino‐5,6‐diphenylpyrazine (XIII), 2°) XIII + SOCl2 → XV. c) An attempt to prepare 2‐methyloxazolo [4,5‐b] pyrazine (XVIII) has been unsuccessfull. d) Some of the new compounds prepared in the course of this work have been characterised by their U. V. spectra (table I p. 148) and their X ray powder diffraction patterns (table II p. 149). Copyright © 1957 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim