Synthesis of mycophenolate mofetil‐[ 14 C], RS‐61443‐ 14 C

Abstract Synthesis of the potent immunosuppressive agent, mycophenolate mofetil ( 1 ) labelled with carbon‐14 is described. Methoxyethoxymethyl (MEM) protected mycophenolate norbromide ( 9 ) was prepared from unlabelled mycophenolic acid ( 2 ) using a modified Hunsdiecker reaction. A three step synthesis furnished the title compound, having a specific activity of 53.8 mCi/mmol, in 49.5% overall yield from K 14 CN.