Scheme 3. Synthesis of Nitroimidazopyrazinones with Biaryl Side Chain 34a–p(32−34).

(i) Pd(PPh₃)₄, K₂CO₃, THF, rt → 80 °C, N₂ ; (ii) NaBH₄, EtOH, rt; (iii) thionyl chloride, DCM, 0 °C → rt; (iv) K₂CO₃, DMF, μW 80–100 °C; (v) nitroimidazole acid chlorideintermediate,²⁷ TEA, DCM, 0 °C → rt; (vi) bromoacetaldehyde diethyl acetal, K₂CO₃, DMF, μW 150 °C; (vii) 1 M HCl, dioxane, μW 120 °C. Intermediate 33a was from a commercial source.