Synthesis, insecticidal and acaricidal activities of tenvermectin acylated derivatives

Twenty-three derivatives of tenvermectin B, tenvermectin B monosaccharide and tenvermectin B aglycone were synthesized by introducing different acyl groups at the C-13, C-4′ and C-4′′ sites after the selective protection of C-5 hydroxyl group. All target compounds were characterized by ¹H NMR, ¹³C NMR and high resolution mass spectra. Their insecticidal activities were tested against Plutella xylostella, Tetranychus cinnabarinus and Bursaphelenchus xylophilus. All the tested compounds showed significant secticidal activities against the above mentioned three insect species and the 4″-tenvermectin B derivatives were superior to the 4′- and 13-derivatives of tenvermectin B. Compound 8e displayed potentactivity to P. xylostella and B. xylophilus with LC₅₀ values of 9.2 mg/L and 0.42 mg/L, respectively. Moreover, compound 8b showed the best inhibitory activity against T. cinnabarinus with LC₅₀ value of 0.001 9 mg/L, which was superior to that of tenvermectin B.