Table 1.

¹H (500 MHz, CDCl₃) and ¹³C (125 MHz, CDCl₃) NMR data and ¹H–¹H COSY and HMBC correlations for norcembrane 1.

Position	δH (J in Hz)	δC, Multiple	1H–1H COSY	HMBC
1	2.79 m	39.4, CH	H2-2, H2-14	C-3, -13, -14, -15
2/2′	2.71 d (16.0); 2.47 dd (16.0, 7.0)	42.8, CH2	H-1	C-1, -3, -4, -14, -15
3		208.7, C
4/4′	3.00 dd (15.5, 11.0); 2.56 (15.5, 7.0)	38.9, CH2	H-5	C-3, -5, -6, -13
5	2.82 m	46.6, CH	H2-4, H-13	C-3, -4, -12, -13, -14
6		198.0, C
7		129.9, C
8		145.6, C
9	2.68 br s	39.1, CH2	H-10	C-7, -8
10	4.50 dd (2.5, 2.5)	79.4, CH	H2-9, H-11	C-8, -11, -19
11	4.15 s	77.0, CH	H-10	C-7, -10, -19
12		52.6, C
13	2.88 m	32.9, CH	H-5, H2-14	C-1, -5, -19
14/14′	2.71 br d (5.5); 2.11 m	28.4, CH2	H-1, H-13	C-1, -5, -12, -15
15		147.1, C
16	1.76 s	21.5, CH3	H-17a	C-1, -15, -17
17a/b	4.86 s; 4.71 s	112.3, CH2	H3-16	C-1, -16
18	2.02 s	21.0, CH3		C-7, -8, -9
19		174.7, C