Controllable Synthesis of Trifluoromethyl- or gem -Difluorovinyl-containing Analogues of Neonicotinoids by the Reaction of α-(Trifluoromethyl)styrenes with 2-Nitroimino-imidazolidine.

A simple and straightforward addition or defluorination of α-(trifluoromethyl)styrenes with 2-nitroimino-imidazolidine ( 2a ), 2-(nitromethylene)imidazolidine ( 2b ), 2-cyanoimino-thiazolidine ( 2c ), and ( E )-1-methyl-2-nitroguanidine ( 2d ), in a controlled manner, was developed. The hydroamination of α-(trifluoromethyl)styrenes with 2a , 2b , 2c , and 2d was completed in the presence of DBN at room temperature within 0.5-6 h, affording structurally diverse β-trifluoromethyl-β-arylethyl analogues of neonicotinoids in moderate to good yields. The γ,γ-difluoro-β-arylallyl analogues of neonicotinoids were also successfully synthesized via defluorination of α-(trifluoromethyl)styrenes, with 2a and 2c using NaH as base at an elevated temperature together with a prolonged reaction time of 12 h. The method features simple reaction setup, mild reaction conditions, broad substrate scope, high functional group compatibility, and easy scalability.