河北医科大学药学院 用于确定六元环中CL,为a或c键（实测17z 向心原则Roof effect OH 18 H NMR:CH1O2 H-NMR Spectrum 向心原则 Roof effoc lines =n+1 NMR Peak integration or peak area NMR Peak Integration or Peak Area 10-CH-C31 天然药物化学教研室史清文教授 河北医科大学药学院 天然药物化学教研室 史清文教授 5 用于确定六元环中CH3为a或e键（实测17Hz） OH CH3 CHO OH 1 2 3 4 H 2 a H 4 e H 2 e 18Hz H3 H3C OH OH H 3 CH3 4 H H 4 H 3 H 2 a H 4 a H 2 a 24Hz H3 HO CHO HO CHO 10Hz 10Hz 10Hz 10Hz 4Hz 4Hz 4Hz 4Hz 4Hz 4Hz 4Hz H2e H2e H2a H2a 205 CH2CH3 向心原则 Roof effect 206 H-2' H-3' Ph-H H-9 H-10 H-5 H-20a H-20b H-13 H-3 H-14a H-14a Aco￾Me-18 Me-19 Me-16 Me-17 1 H-NMR Spectrum O AcO H H OAc HO O 1 3 5 7 9 11 13 15 17 18 19 20 1' 2' 3' 208 NMR Peak Integration or Peak Area NMR Peak Integration or Peak Area a) The relative peak intensity or peak area is proportional to the number of protons associated with the observed peak. b) Means to determine relative concentrations of multiple species present in an NMR sample. HO-CH2-CH3 1 Integral trace Relative peak areas = Number of protons 2 3