gel-promoted synthesis of 2-bromo-3-hydroxybenzoate derivatives has been developed via the Diels–Alder reaction of furans with methyl 3-bromopropiolate, followed by a ring-opening aromatization. In addition, 2-bromo-3-methoxybenzoate, derived from 2-bromo-3-hydroxybenzoate with iodomethane, was found to be a good substrate for Pd-catalyzed cross-coupling reactions, despite its sterically hindered structure
Mechanistic study of silica-gel or FeCl3-promoted ring-opening aromatization of 7-oxanorborna-2,5-dienes affording 2-bromo-3-hydroxybenzoate derivatives
One-pot synthesis of 2-bromo-3-hydroxybenzoates by the Diels–Alder reaction of furans with bromoalkyne and the subsequent ring-opening aromatization was studied by means of deuterium-labeling experiments. The residual protons in silica gel were considered to be the hydrogen source of the hydroxy group of products under the silica gel-promoted condition. The deuterium-labeling experiment revealed a rapid equilibrium among the intermediates prior to the aromatization under FeCl3-catalyzed condition.