Diazonium fluoroborates carboxylic acids

Carboxylic acids can be prepared in moderate-to-high yields by treatment of diazonium fluoroborates with carbon monoxide and palladium acetate or copper(II) chloride. The mixed anhydride ArCOOCOMe is an intermediate that can be isolated. Other mixed anhydrides can be prepared by the use of other salts instead of sodium acetate." An arylpalladium compound is probably an intermediate." ... 

Carboxylic acids can be prepared in moderate-to-high yields by treatment of diazonium fluoroborates with carbon monoxide and palladium acetate or... 

With diazonium fluoroborates." In the presence of acetone or acetic acid, nickel carbonyl reacts with a diazonium fluoroborate to form the carboxylic acid in yields in the range 5-70%. 

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