Table 3.

Synthesis of 3-alkynyl substituted 2-chloroquinoxaline derivatives (3)^a,b (Scheme 1).

^aAll reactions were carried out using the chloro compound 1 (1 equiv.), alkyne 2 (1 equiv.), CuI (15 mol%), PPh₃ (30 mol%) and K₂CO₃ (2 equiv.) in PEG-400 (5.0 mL) at 50 °C under ultrasound irradiation.

^bFigure in the bracket represents isolated yield.

^c1.5 equivalent of alkyne (3,3-dimethylbut-1-yne) was used in this case.