°Nu RC—Y—RC-NuY—离去基团 R-C—NH2R-C-OR'R-C-OCOR'R-C—X 反应性增强 R R R RIC-C-Y DC-CY HI C-C-Y H C-C-Y R H H HOrganic Chemistry Organic Chemistry Xiamen Xiamen University University R C O Y Nu R C O Nu Y 离去基团 R C O NH 2 R C O OR' R C O OCOR' R C O X 反应性增强 C C O Y R R R C C O Y R H C C H O Y R H R C C O Y H H H