Design, Synthesis, and Bioactivity Study of α-Thiocyanato-Substituted Spirocyclic Tetramic Acid Derivatives

Area of Science:

• Agricultural Chemistry
• Organic Synthesis
• Pesticide Development

Background:

• Spirocyclic tetramic acids are a known class of bioactive compounds used as pesticides.
• There is a continuous need for novel pesticide molecules with improved efficacy and reduced environmental impact.

Purpose of the Study:

• To synthesize novel spirocyclic tetramic acid derivatives incorporating a thiocyanato (SCN) group.
• To evaluate the insecticidal, acaricidal, and herbicidal activities of these new compounds.
• To assess the toxicity profile, particularly embryotoxicity in zebrafish, and systemic translocation properties.

Main Methods:

• Synthesis of α-SCN-substituted tetramic acid derivatives via electrophilic thiocyanation.
• Bioassays to determine acaricidal activity against *Tetranychus cinnabarinus* and insecticidal activity against *Aphis craccivora*.
• Herbicidal activity screening against gramineous weeds and embryotoxicity assessment in *Danio rerio*.
• Systemic translocation studies in plants.

Main Results:

• Compounds C16 and C20 demonstrated superior acaricidal activity against *Tetranychus cinnabarinus* compared to spirodiclofen.
• Compound C1 showed insecticidal activity against *Aphis craccivora* comparable to spirotetramat.
• Compounds C16 and C28 exhibited significant herbicidal activity against gramineous weeds.
• Reduced embryotoxicity was observed for C1 and C16 in zebrafish compared to existing pesticides.
• Bioactive compounds C1 and C16 displayed systemic translocation properties similar to spirotetramat.

Conclusions:

• The rational incorporation of the SCN group into spirocyclic tetramic acid structures yields derivatives with high bioactivity.
• These novel compounds exhibit promising insecticidal, acaricidal, and herbicidal properties with a favorable toxicity profile.
• The developed SCN-substituted spirocyclic tetramic acids represent a valuable avenue for the innovation of environmentally friendly pesticide alternatives.