Table 1.

¹H NMR chemical shifts (δ_H), chemical shift differences (Δδ_H, exo - endo), multiplicities (m), and coupling constants (J) for the endo and exo protons at C15 of various ent-beyerane derivatives

Compound No.	X	H15 δH (ppm)	ΔδH (ppm)	m	J (Hz)
16	C=O	endo 1.75 exo 2.68	0.93	d dd	18.6 18.6, 3.6
19	C=NOH	endo 1.94 exo 3.02	1.08	d dd	18.4 19, 3.2
23	NCO2Me	endoa 2.90 endob 2.97 exoa 3.89 exob 3.98	0.99a 1.01b	d d dd dd	11 11 11, 2 11, 2
12	NH	endo 2.56 exo 3.40	0.84	br d br d	10.8 10.8
13	N	endo 2.28 exo 3.20	0.92	dd d	12, 1.6 11.6
25a	CHOH (endo OH)	endo NDc exo 1.85	NDc	NDc ddd	NDc 14.3, 4.8, 2.6
25b	CHOH (exo OH)	endo NDc exo 2.59	NDc	NDc ddd	NDc 14.3, 7.6, 2.4

^aMajor rotamer.

^bMinor rotamer.

^cND = not determined.