Semisynthesis of Nocarterphenyl A and Its Analogues

<i>p</i>-Terphenyl compounds are known to possess a diverse range of biological activities, making the synthesis of novel <i>p</i>-terphenyl derivatives a significant research objective. In this study, we report the first synthesis of nocarterphenyl A (<b>1</b>), characterized by a thiazole-fused <i>p</i>-terphenyl framework. Furthermore, we synthesized 18 additional analogs, including the naturally occurring compound 5-methoxy-4,7-bis(4-methoxyphenyl)benzo[<i>d</i>]thiazol-6-ol (<b>9</b>), employing a similar synthetic approach. Notably, compounds <b>12</b>, <b>13</b>, <b>15</b>-<b>17</b>, and <b>19</b> 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 <b>14</b> 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).