Synthesis of carboxylic acids based on the closo-decaborate anion

A series of new boron-containing carboxylic acids was prepared by the ring-opening reaction of cyclic oxonium derivatives of the closo-decaborate anion [B10H10]2− with methyl esters of hydroxybenzoic acids or the cyanide anion followed by hydrolysis of the obtained nitrile and esters. Acid hydrolysis of the esters results in protonation of the oxygen atom connected to the boron cage, with the formation of the corresponding O-protonated acids, isolated in the solid state. The compounds synthesized can be used in radionuclide diagnostics and boron neutron capture therapy of cancer.

A series of boron-containing carboxylic acids was prepared by the ring-opening reaction of the cyclic oxonium derivatives of the closo-decaborate anion [B10H10]2− with methyl esters of hydroxybenzoic acids followed by acid hydrolysis of the obtained esters.Figure optionsDownload as PowerPoint slideHighlights
► Reactions of cyclic oxonium derivatives with hydroxybenzoic acids were studied.
► New closo-decaborate based carboxylic acids were synthesized.
► Protonation of the oxygen atom bounded directly to the decaborate anion was revealed.