Table 3.

The ¹H and ¹³C NMR (DMSO-d₆, 300.13 and 75.4 MHz) and HMBC assignment for 4.

Position	Δc, Type	δH, (J in Hz)	COSY	HMBC
2a	69.8, CH2	4.49, d (12.4)	2b	C-4, 4′, 8a
2b		4.63, d (12.4)	2a	C-3, 4, 4′, 8a-
3	86.3, C	-	-	-
4	181.6, CO	-	-	-
4a	111.1, C	-	-	-
5	110.3, CH	7.05, s	-	C-4, 6, 7, 8a
6	141.9, C	-	-	-
7	155.9, C	-	-	-
8	103.2, CH	6.41, s	-	C-4, 4a, 6, 7, 8a
8a	156.9, C	-	-	-
2′	191.4, C	-	-	-
3′	103.8, CH	5.68, d (0.8)	5′	C-2′, 3, 4′
4′	198.3, CO	-	-	-
5′	16.4, CH3	2.31, s	3′	C-2′, 3′
OH	-	10.01, brs	-	-