7 抗生物質Boxazomycin A,B及びCの構造

抄録

Boxazomycins A, B and C are antibiotics isolated from Pseudonocardia species. Their structures have been elucidated as 1, 2 and 3, respectively, by use of modern NMR technics including INADEQUATE, NH-COSY, NH-COLOC and CP/MAS. In the last spectrum, signals of carbons which are bonded to a nitrogen atom are splitted (or broadened), and this technic has been found to be very useful in the present work. In the INADEQUATE spectrum of 4, connectivity peak between C-4' and 5' was not observed, because the chemical shifts of both the carbons are very close. This problem was overcome by converting boxazomycin A(1) into diphosphate(7), the ^<13>C-NMR spectrum of which revealed the long-range coupling(Jcp) from 5'-O-P to C-4'. This finding suggests that C-4' is connected with C-5'. Assignments of all the nitrogen atoms were done by analysis of NH-COSY and NH-COLOC spectra. The structure of boxazomycins is unique in that a benzoxazole moiety is combined with a pyrimidine ring.