In the beginning, we chose quinoxalin-2(1
H)-ones (
1a) and isopropyl boronic acid (
2a) as starting substrates, CF
3CO
2H as Catalyst, 1,2-dichloroethane (DCE) as solvent, the yield of
3a was 51% under oxygen atmosphere and 100 ℃ (
Table 1, entry 1). When the temperature dropped to 80 ℃ or 60 ℃, the yields immediately drop to 23% and 14% (
Table 1, entries 2 and 3). Conversely, when the reaction temperature was increased to 120 ℃, the yield increased to 72%, while a further increase in temperature did not significantly increase the yield (
Table 1, entries 4 and 5). Subsequently, when the catalyst was CH
3CO
2H, CH
3SO
3H, CF
3SO
3H or Et
3N, the reaction effect was not as good as CF
3CO
2H, but unexpectedly, the reaction could give product
4a in 40% yield under CH
3CO
2H condition (
Table 1, entries 6–10). After screening the reaction solvent, we found that CH
3CN was the most suitable solvent for this reaction, compared with DCE, 1,4-dioxane, dimethylsulfoxide (DMSO), THF, acetone and H
2O (
Table 1, entries 11–16). Finally, when the gas atmosphere was air, 26% of
3a and 23% of
4a were obtained (
Table 1, entry 17). The reaction hardly proceeded under N
2 atmosphere (
Table 1, entry 18). This shows that O
2 was essential for the transformations. Combining entry 6, we believed that under the condition of using CH
3CO
2H as a catalyst, 120 ℃ and an oxygen atmosphere, by changing the reaction solvent, the most favorable reaction condition for the formation of
4a may be found. By screening the solvent, acetone came to the fore, it can increase the yield of product
4a to 90% without the formation of
3a (
Table 1, entries 19–24). Similarly, in order to determine the most suitable gas atmosphere for
4a, we tried to change the oxygen atmosphere to air or nitrogen. It can be seen from
Table 1, entries 25 and 26 that when the reaction atmosphere was changed to air, the yield of
4a was not affected and the nitrogen atmosphere greatly hinders the production of
4a. Therefore, the CH
3CO
2H/acetone system only needs air atmosphere, which relatively reduces the experimental operation steps.