Synthesis of optically pure Cα-methyl-arginine

Optically pure L‐(+)‐Cα‐methyl‐arginine and D‐(‐)‐C α‐methyl‐arginine were synthesized. Experimental results indicated that DL‐ Cα‐methyl‐arginine methyl ester could be resolved by trypsin, but workup posed a technical difficulty. Chemical resolution at the stage of DL‐Cα‐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 Cα‐methyl‐arginine.