Regioselective addition of alkyl phosphites on 6-(aryliminomethyl)-furobenzopyran-5-one derivatives

Aim Trialkyl phosphites 2a,b attack 6-(aryliminomethyl)furobenzopyran-5-ones 1a–e regiospecifically at the carbon–carbon double bond of the γ-pyrone ring to yield new 1,2-addition phosphonate products for which structures 3a–e have been respectively assigned. Methods The alkyl phosphites 2a,b attacked the monoanils 1a–e at the azomethine carbon of the C=N bond to yield corresponding phosphonate adducts 5a–e when reactions were carried out in the presence of a controlled amount of acetic acid. Phosphonates 5a–e could also be obtained by the reaction of dialkyl phosphites 4a,b with anils 1a–e. Structures of the new phosphonates 3a–e were elucidated by elemental analyses as well as spectroscopic methods. The 1 H and 13 C nuclear magnetic resonance and infrared measurements were helpful tools in confirming the structures of the new products. Results and conclusion The insecticidal activities of phosphonates 3a–e and their respective regioisomers 5a–e against adult Aphis gossypii (Glover), which infest cotton crops, were determined. The structure–activity relationship has been discussed.