Abstract
Five substituted benzenesulfonyl groups, p-toluenesulfonyl, p-methoxybenzenesulfonyl, 2, 4-dimethoxybenzenesulfonyl, 2, 4, 6-trimethoxybenzenesulfonyl, and 4-methoxy-2, 3, 6-trimethylbenzenesulfonyl, were introduced at Nin of tryptophan and their protecting group properties were investigated. Among them, 2, 4, 6-trimethoxybenzenesulfonyl and 4-methoxy-2, 3, 6-trimethylbenzenesulfonyl are stable to trifluoroacetic acid, but can be readily removed by hydrogen fluoride or methanesulfonic acid, and suppress decomposition and modification of the tryptophan residue during peptide synthesis. These protecting groups were successfully used in syntheses of bombesin, a potent analog of luteinizing hormone-releasing hormone by the solution method and dynorphin by the solid-phase method.
