A compound of the formuia:
in which R' is hydrogen, halogen, amino, acyiamino, isocyano or protected hydroxy(lower)alkyl,
R2 is hydrogen or an organic group optionally substituted by suitable substituent(s). and
R3 is carboxy or a protected carboxy group, or a salt thereof.
The invention also relates to processes for their preparation, and their use for preparing antibiotics.
其中 R'为氢、卤素、
氨基、酰
氨基、异
氰基或受保护的羟基(低级)烷基,R2 为氢或任选被适当取代基取代的有机基团,R3 为羧基或受保护的羧基,或其盐。 本发明还涉及其制备工艺及其用于制备抗生素的用途。