Table 1. ¹H and ¹³C NMR data for tambjamine YP1 and its novel cyclized variant in CDCl₃.

Position	Tambjamine MYP1		Tambjamine YP1 a
	δ H (J in Hz)	δ C	δ H	δ C
1′ (NH)
2′	—		—	123.5
3′	6.63, s*	113.5	6.70	113.0
4′	5.99, s*	109.7	6.25	110.5
5′	—		7.06	124.1
1 (NH)
2	—	142.1	—	143.4
3	5.87, s	90.4	5.95	91.6
4	—	163.0	—	163.9
OMe	3.92, s	58.5	3.90	58.8
5	—	110.1	—	111.3
6	7.14, d (14.77)	140.1	7.29	141.1
7 (NH)	9.29, br d
8	3.54, br	51.4	3.46	51.2
9	2.50, m	27.8	2.46	28.8
10	5.22, dt (10.89, 7.70)	123.2	5.35	124.1
11	5.55, dt (10.89, 7.20)	137.1	5.55	134.5
12	2.06, m (7.20)	27.4	2.01	27.8
13	1.22, m	28.6–31.8 c	1.21–1.70 d	26.5–27.7 d
14	0.85–1.29 b
15
16
17
18	1.82, m	27.7
19	2.75, br t (6.10)	27.2	0.86	14.5

^aData from ref. 9.

^bValue ranges for positions 14–17.

^cValue ranges for positions 13–17.

^dValue ranges for positions 13–18.