Synthesis of 7-hydroxy-2-(2-hydroxybenzoyl) benzo [c] chromen-6-ones by sequential application of domino reactions of 1, 3-bis (silyl enol ethers) with benzopyrylium …
The domino, Michael–retro-Michael–aldol, reaction of 2, 4-bis (trimethylsilyloxy) penta-1, 3- diene with 3-formylchromones afforded 4-(2-hydroxybenzoyl)-2-acetylphenols, which were transformed into 6-(2-hydroxybenzoyl) chromones. The Me3SiOTf-mediated condensation of the latter with 1, 3-bis (silyl enol ethers) and subsequent domino 'retro-Michael–aldol– lactonization'reaction afforded 7-hydroxy-2-(2-hydroxybenzoyl) benzo [c] chromen-6-ones.
