Table 1.

¹H (700 MHz) and ¹³C NMR (176 MHz) data for 1 and 2 in DMSO-d₆.

Position	1		2
	δC, Type	δH, Mult (J Hz)	δC, Type	δH, Mult (J Hz)
1	115.3, C		117.3, C
2	127.5, C		128.0, C
3	137.6, C		136.1, C
4	137.0, C		136.4, C
5	109.4, CH	7.37, d (8.6)	108.6, CH	7.30, d (8.5)
6	124.0, CH	7.57, d (8.6)	123.6, CH	7.58, d (8.5)
7	168.6, C		169.2, C
8-NH		10.94, br s		10.97, br s
9	171.3, C		174.5, C
10	23.6, CH3	2.21, s	29.8, CH2	2.49, overlapping
11			9.8, CH3	1.17, t (7.6)
12-NH		8.94, s		8.84, s
14	144.2, C		143.3, C
15	196.3, C		196.2, C
16	8.1, CH3	2.00, s	7.9, CH3	1.99, s
17	24.2, CH3	2.40, s	24.1, CH3	2.40, s
3-OH		10.18, br s		n.d.
1-COOH		13.00, br s		13.09, br s

“n.d.”: not detection. Data were recorded on a Bruker Avance 700 MHz NMR spectrometer in DMSO-d₆ with TMS as an internal standard. The signals were assigned with the aid of ¹H-¹H COSY, HSQC, and HMBC data.