(3)H3 (1) cH3.△ (2)HOAc, NaOAc,H2O,△ H3c Robinson关环 对比 CH H3C CH (1)NaOH/H2O H3C NaoC? H (2)H’,△ H2cO H3C N H H + H3C N CH3 O (1) , (2) HOAc, NaOAc, H2O, O H3C O H3C H3C O   (3) Robinson关环 O H3C CH3 O NaOC2H5 O H3C O CH3 (1) NaOH/H2O (2) H + ,  H3C O 对比