Synthesis and biological activities of α-pinene-based dithiadiazoles

This work is aiming at the preparation of new bioactive compounds from alpha-pinene as starting material. To this purpose, the intermediates (disubstituted phenyl acylamino thioureas, class G) were cyclized to dithiadiazoles (class H). The intermediates and target compounds were analyzed by Fourier transform infrared, H-1 nuclear magnetic resonance (NMR), C-13 NMR, and electrospray ionization-mass spectrometry and elemental analysis. The bioassay experiments showed that the compounds G and H have herbicidal, fungicidal, and plant growth-regulating activities. The compounds 2,2'-dimethylphenyl thiadiazole and 3,3'-dimethylphenyl thiadiazole exhibited a growth inhibition activity of 72% and 68% against the root of rape (Brassica campestris L.) at a concentration of 100 mu g ml(-1) (60-79% inhibition level). The compound 4,4'-dichlorophenyl acylamino thiourea displayed an inhibition activity of 75% against Physalospora piricola at a concentration level of 50 mu g ml(-1) (60-79% inhibition level).