C57H66N2O4. The 1
H NMR spectrum (Table 1) of 3 was also
akin to that of compound 2, showing the lack of signals at δ
7.66 (11″-NH) and 5.23 (7″-OH). Instead, the 1
H NMR
spectrum showed two three-proton singlets at δ 3.86 and 4.09
as well as two one-proton singlets at δ 7.93 (H-7″) and 6.98
(H-10″). Signals at δ 3.86 and 4.09 showed HSQC cross-peaks