Praseodymium(III)-Catalyzed Regioselective Synthesis of C<sub>3</sub>‑N-Substituted Coumarins with Coumarins and Azides LiJiu-ling HuDa-chao LiangXin-ping WangYing-Chun WangHeng-Shan PanYing-ming 2017 A series of C<sub>3</sub>-N-substituted coumarins were synthesized in good yields directly from coumarins and azides in the presence of Pr­(OTf)<sub>3</sub> without any additives or ligands needed. The selected compounds <b>3a</b>, <b>3c</b>–<b>e</b>, <b>3g</b>, <b>3i</b>, <b>3q</b>, <b>3u</b>, and <b>3v</b> exhibited good anticancer activities against MGC-803, A549, and NCI-H460 cell lines with IC<sub>50</sub> in the range 8.75–38.54 μmol L<sup>–1</sup>.