Synthesis of 3‑(2-Olefinbenzyl)‑4H‑chromen-4-one through Cyclobenzylation and Catalytic C–H Bond Functionalization Using Palladium(II)

An efficient strategy for synthesizing 3-(2-olefinbenzyl)-4H-chromen-4-one in two steps was developed. The first step is a cyclobenzylation reaction between (E)-3-(dimethylamino)-1-(2-hydroxyphenyl)­prop-2-en-1-one and benzyl bromide to produce homoisoflavonoid. The second step involves intermolecular Pd-catalyzed π-chelating-assisted C–H bond olefination. Using the C-2/C-3 double bond of chromone, palladium-catalyzed aryl C–H bond activation can be functionalized to generate ortho-olefination derivatives in moderate to high yields.