Natural Product Cerbinal and Its Analogues Cyclopenta[ c ]pyridines: Synthesis and Discovery as Novel Pest Control Agents.

Owing to the changing needs of agriculture, the exploration of new pest control agents remains as critical as ever. The analogues 3a - 3v of the natural product cerbinal were synthesized from genipin by an efficient and practical method under additive-free conditions. The antiviral and insecticidal effects of cerbinal and these cyclopenta[ c ]pyridines ( 3a - 3v) were evaluated systematically. Most of the synthesized compounds exhibited higher anti-TMV activities than the lead compound cerbinal. Compound 3s (2-(4-methoxyphenyl)) had the most promising inhibitory activities against TMV (inactivation effect 49.0 ± 0.8%, curative effect 41.2 ± 4.3%, and protection effect 51.5 ± 2.7% at 500 μg/mL). Among the synthesized compounds, only 3v (2-(2-chloro-4-(trifluoromethoxy)phenyl)) reached the activity level of cerbinal against Plutella xylostella . This suggested that the cyclopenta[ c ]pyridines obtained by modifications of cerbinal at position 2 are very significant for the anti-TMV activity, and yet were exceptionally less active for the insecticidal activities.