Table 1.

¹³C–¹H HMBC correlations for 23.

Hydrogen	Carbon	C-2	C-3	C-4	C-4′	C-5	C-6	C-7	C-8	C-8′
	(ppm)	159.5	124.0	136.7	118.8	139.6	138.9	143.1	116.3	146.3
H-3	6.75	α	linked	α	β	-	-	-	-	-
H-4	7.77	β	α	linked	α	β	-	-	-	β
H-8	8.23	-	-	-	β	-	β	α	linked	α