Total Synthesis and Structure Revision of Palmarumycin B 6 .

Palmarumycin B ₆ and its regioisomer were synthesized via 7- and 13-step routes using 2-chlorophenol and 4-chlorophenyl methyl ether as the starting materials in overall yields of 2.7% and 12%, respectively. Their structures were characterized by ¹ H and ¹³ C NMR, HRESIMS, and X-ray diffraction data. The structure of palmarumycin B ₆ was revised as 6-chloropalmarumycin CP ₁₇ . The bioassay results showed that the larvicidal activity of palmarumycin B ₆ with an LC ₅₀ value of 32.7 μM was significantly higher than that of its 8-chloro isomer, with an LC ₅₀ value of 227.3 μM.