Divergent synthesis of 3,4-dihydro-2 H -benzo[ h ]chromen-2-one and fluorenone derivatives from ortho -alkynylarylketones.

Our research has led to the development of a divergent synthesis approach for the synthesis of 3,4-dihydro-2 H -benzo[ h ]chromen-2-one 3 and fluorenone 9 derivatives using ortho -alkynylarylketones as common precursors. The synthesis of 3,4-dihydro-2 H -benzo[ h ]chromen-2-ones 3 employed silver catalyzed ketonization to form polycarbonyl intermediates which underwent double intramolecular cyclization and decarboxylation to generate a lactone and a phenyl ring in a one-pot fashion. In addition, the same precursor could be used to prepare fluorenone derivatives 9 under acidic conditions. The reaction proceeded via the formation of indenone analogs, followed by the generation of the para -quinone methide intermediate and intramolecular cyclization to provide the corresponding products in good yields.