0 ⑤ 0 ·H、HgH构成三旋系统ABX H82.83,H83.14,H85.40 Jax=4 HZ JAx-11 Hz 将值代入上式，可知BX间的夹角近于 60°，AX间的夹角近于180° 盘从g 盐 护0 处给垫 的胶 9 degree) 49(45 degree (IH.br.d.J-3.0 Hz.H-5 273 213 Figure 2. A priori magnitude estimation of J values as a function of dihedral angle ã (degrees) between interested nuclei. 214 • HA HB HX构成三旋系统ABX • HB d 2.83, HA d 3.14, HX d 5.40 • JBX=4 Hz, JAX=11 Hz • 将J值代入上式，可知BX间的夹角近于 60°，AX间的夹角近于180° O O Ha Hx Hb CH3 H3C HO HO OH 215 O O OCH3 OH HO 2 3 216 O O OCH3 OH H3CO OH 3 2 217 O Ha Ph Hb O O Ha Hb Ph O Jab » 0 (90 degree) Jab » 4-9 (45 degree) 218 (1H, br. d, J = 10.6 Hz, H-5) (1H, br. d, J = 3.0 Hz, H-5) O CH3 O H H CH3 H H HO HO H H5 O CH3 O H H H3C H H HO HO H H5