Amino acid analogs of benanomicin A through desalaninebenanomicin A

Desalaninebenanomicin A has been synthesized in good yield by the cleavage of the amido bond of benanomicin A using MEERWEIN's reagent. This is a useful intermediate to prepare amino acid analogs of benanomicin A. MEERWEIN's reagent reacts with totally protected benanomicin A to give a stable imino ether. After deprotection, the imino ether is treated with aqueous acetone at reflux to afford a methyl ester of desalaninebenanomicin A. Desalaninebenanomicin A was coupled with a variety of amino acids by the active ester method to afford new benanomicin analogs.