First Synthesis Of [1,3,5-~(13)c_3]gallic Acid

摘要

An efficient and high-yielding synthesis for [1,3,5-~(13)C_3]gallic acid from non-aromatic precursors is presented. [3,5-~(13)C_2]4H-Pyran-4-one was first prepared from the reaction between triethyl orthoformate and [1,3-~(13)C_2]acetone. The third ~(13)C-atom was introduced into the ring by reaction of the pyranone with diethyl [2-~(13)C]malonate. The resulting ethyl 4-hydroxy-[1,3,5-~(13)C_3]benzoate was brominated in the 3-and 5-positions to give ethyl 3,5-dibromo-4-hydroxy-[1,3,5-~(13)C_3]benzoate. Subsequent hydrolysis of the ester and substitution of the bromine atoms with hydroxyl groups was achieved under basic conditions in a single step to yield the desired [1,3,5-~(13)C_3]gallic acid. The synthesis of [2,6-~(13)C_2]4H-pyran-4-one is also presented to demonstrate the potential of the methodology for the regioselective placement of ~(13)C-atoms into benzene rings.