The oxazole moiety of the noviosylcoumarinooxazole 6 was found to be cleaved selectively under mild acidic conditions to produce 3-amino-4-hydroxycoumarins 3 without destruction of the glycosidic bond. By use of this selective oxazole cleavage reaction, a new process to key intermediates for the synthesis of coumermycin analogues PNC-aminel 3a and 2'-aoetyl PNC-amine 3b has been developed by starting from coumermycin Al (1). This process ...