Synthesis of 3-Arylacetamides Substituted Maleimide Via Weakly Coordinating Acetamide Assisted Cross-dehydrogenative Coupling and Their Photophysical Studies

Maleimides serve as an important synthetic precursor for various organic transformation reactions. However, maleimides have been rarely employed as coupling partners for the direct synthesis of 3-aryl substituted maleimides via oxidative Heck-type reaction, due to the lack of beta-hydrogen at the syn-periplanar position. Therefore, herein, we report an efficient and highly selective synthesis of 3-arylacetamide incorporated maleimides through the cross-dehydrogenative coupling process using the simple and native primary acetamide as a weakly directing group with Pd(II)-catalysis conditions. This reaction furnishes 3-arylated maleimide derivatives in good yields with high functional group tolerance. Furthermore, 3-arylated maleimides were transformed into synthetically important derivatives. Based on preliminary control experiments, a probable reaction mechanism has been proposed for the distal C-H bond functionalization reaction. Interesting photophysical properties of the synthesized products were also observed.