Synthesis and Herbicidal Activity of Terpinyl Phthalimide Derivatives

Using α-terpinene(1) as the starting material, dimethyl terpinylbutenedioate(2) was synthesized through its Alder-Rickert reaction with dimethyl butenedioate. Terpinyl phthalic anhydride(3) was subsequently synthesized by their ring-closing reaction. Afterwards, 13 novel terpinyl phthalimide derivatives(4a-4m) were synthesized by the substitution reactions of compound 3 with a series of aromatic amine compounds. The structures of the target compounds were characterized by IR, ESI-MS, ¹H NMR and ¹³C NMR, and the successful synthesis of the target compounds 4a-4m was confirmed. Preliminary herbicidal activity tests results showed that most synthetic compounds exhibited certain herbicidal activity against Echinochloa crusgalli(L.) Beauv, Digitaria sanguinalis(L.) Scop., Abutilon theophrasti Medicus and Amaranthus retroflexus when they were applied to the stems and leaves at a dosage of 1.5 kg/hm². Among them, compounds 4b(R=p-CH₃) and 4c(R=p-OCH₃) showed the highest inhibitory activity and reached grade B against A. theophrasti Medicus with the inhibition rates of 62.2% and 64.0%, respectively.