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 triflates

Abstract: 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. [Copyright &y& Elsevier]