Semisynthesis of Nocarterphenyl A and Its Analogues

p-Terphenyl compounds are known to possess a diverse range of biological activities, making the synthesis of novel p-terphenyl derivatives a significant research objective. In this study, we report the first synthesis of nocarterphenyl A (1), characterized by a thiazole-fused p-terphenyl framework. Furthermore, we synthesized 18 additional analogs, including the naturally occurring compound 5-methoxy-4,7-bis(4-methoxyphenyl)benzo[d]thiazol-6-ol (9), employing a similar synthetic approach. Notably, compounds 12, 13, 15–17, and 19 demonstrated potent inhibitory effects against protein tyrosine phosphatase 1B (PTP1B), exhibiting IC50 values ranging from 2.2 to 7.9 μM, which are lower than that of oleanolic acid (13.2 μM). Additionally, compound 14 was found to inhibit α-glucosidase from human colorectal adenocarcinoma (Caco-2) cells with an IC50 value of 10.4 μM, which is also lower than that of acarbose (11.2 μM).