Antibiotics and process for production thereof

摘要

A compound represented by the following formula <IMAGE> (I) <IMAGE> wherein R represents a hydrogen atom or a methyl group, R1 represents a hydrogen atom or an ester residue, and R2 and R3 represent hydrogen atoms respectively, or taken together, a group of the formula <IMAGE> in which each of R4 and R5 represents a hydrogen atom, a lower alkyl group or a phenyl group, and its salt; and a process for the production thereof.