Synthesis of optically pure Cα‐methyl‐arginine

Optically pure L‐(+)‐C α ‐methyl‐arginine and D‐(‐)‐C α ‐methyl‐arginine were synthesized. Experimental results indicated that DL‐ C α ‐methyl‐arginine methyl ester could be resolved by trypsin, but workup posed a technical difficulty. Chemical resolution at the stage of DL‐C α ‐methyl‐ornithine, followed by selective guanid‐ination using N,N ′‐di‐Cbz‐S‐methylisothiourea and hydrogenolysis provided a effective and practical method for the synthesis of optically pure C α ‐methyl‐arginine.