¹H and ¹³C NMR data (400 MHz for ¹H, and 100 MHz for ¹³C) of compound 10^a.

Position	10b
	δ H	δ C
1		129.8
2	7.06 s	110.1
3		145.0
4		141.9
4a		117.1
4b		127.3
5	8.80 d (9.2)	123.7
6	7.28 d (9.2)	112.7
7		149.9
8		143.2
8a		123.6
9	7.92 d (9.6)	118.6
10	7.81 d (9.6)	122.9
10a		125.1
11	3.29 m	31.4
12	3.14 m	61.9
OCH2O	6.19 s	100.9
7-OCH3	4.00 s	56.3
8-OCH3	3.98 s	61.2
N–CH3	2.81 s	46.9
	2.09 s	19.5
		169.7

^aAssignments were based on ¹H–¹H COSY, HMQC, HMBC, and NOESY experiments; chemical shifts (δ) are given in ppm.

^bRecorded in CDCl₃.