The selective protection of piperazine-2-carboxylic acid (I) with tert-butoxycarbonyl anhydride gives the carbamate (II), which is sulfonated with 4-methoxybenzenesulfonyl chloride (II) and triethylamine yielding the sulfonamide (IV). The esterification and simultaneous deprotection of (IV) with SOCl2 and methanol affords the methyl ester (V), which is treated with benzyl chloroformate (VI) and triethylamine to afford the benzyloxycarbonyl derivative (VII). Finally, this compound is treated with KOH and hydroxylamine in methanol to provide the target hydroxamic acid.

The selective protection of piperazine-2-carboxylic acid (I) with tert-butoxycarbonyl anhydride gives the carbamate (II), which is sulfonated with 4-methoxybenzenesulfonyl chloride (II) and triethylamine yielding the sulfonamide (IV). The esterification and simultaneous deprotection of (IV) with SOCl2 and methanol affords the methyl ester (V), which is treated with phosgene and N-benzyl-N-methylamine (VI) to afford the cyclic urea derivative (VII). Finally, this compound is treated with KOH and hydroxylamine in methanol to provide the target hydroxamic acid.

The selective protection of piperazine-2-carboxylic acid (I) with tert-butoxycarbonyl anhydride gives the carbamate (II), which is sulfonated with 4-methoxybenzenesulfonyl chloride (II) and triethylamine yielding the sulfonamide (IV). The esterification and simultaneous deprotection of (IV) with SOCl2 and methanol affords the methyl ester (V), which is treated with benzyl chloroformate (VI) and triethylamine to afford the benzyloxycarbonyl derivative (VII). Finally, this compound is treated with KOH and hydroxylamine in methanol to provide the target hydroxamic acid.