The optimization table for the C-H biarylation of Nphthaloyl-L-alanine (19) and aryl iodide 18 is shown (Figure ). Initially, following the work of Zhao et al., the investigation of ligands was conducted in the presence of Pd(OAc)2 catalyst, with the utilization of 1.0 equivalent of Ag2CO3 and 0.5 equivalents of K2CO3. As a result, when Ac-L-Phg-OH, Ac-L-Leu-OH, Ac-L-Ile-OH, Ac-L-Phe-OH, Ac-L-Ala-OH, and Ac-L-Val-OH were employed, the desired compound 22 was obtained with moderate yields ranging from 60% to 75% (Table , entries 1-6). Similarly, when Ac-D-Leu-OH and Ac-D-Phe-OH were employed, the C-H biarylation proceeded with moderate yields, although these two were in the moderate range (entries 7, 8). Further investigation of the ligands revealed that when Ac-Gly-OH was used, the desired compound 22 was obtained with the highest yield of 89% (entry 9). It is worth noting that this reaction also proceeded favorably on a gram scale with a yield of 71% (entry 10). Interestingly, when Boc-Gly-OH was used, as mentioned earlier, only traces of 22 were obtained. This indicates the essentiality of the Ac group in this reaction (entry 11).