Solvent-Free Synthesis and Insecticidal Activities of C6-Esterified Coumarins

2-Methylbenzene-1,4-diol was reacted with ethyl 3-oxobutanoate in concentrated sulfuric acid to generate 6- hydroxycoumarins (2a-b), which were milled with anhydrous K2CO3, aryl chloride under solvent-free conditions, resulting in the formation of C6-esterified coumarins (3a-ss) in good to excellent yields. The structures of all title compounds were confirmed by 1H NMR, MS and elementary analyses. The preliminary bioassay indicated some title compounds, such as 3f, 3h, 3m, 3t, 3u, 3x, 3aa, 3bb, 3ff, 3gg, 3ii, 3ll, and 3nn to have over 90% insecticidal activities against several insects at 100 mg/L. Keywords: Coumarins, insecticidal activities, solvent-free, synthesis.