Synthetic Studies On Isocopalane Diterpenes

The thesis contains two chapters:(1)Synthesis of isocopalane diterpenes bearing methyl group at C-17;(2)Synthesis of isocopalane diterpenes in conjunction with the oxygenation patterns at C-17.Chapter Ⅰ:Organic process leading to LBZ impurity was achieved using potassium persulfate as catalyst with 88%yield.Then,the synthesis of ent-Spongian-16-one using isocopalane building block 2-4 as starting material was conducted based on the previous work which went through deacetylation,thioacetalization,mesylation,elimination and reduction in 58%overall yield.At the same time,intermediate 2-8 was used as precursor for the synthesis of furanospongian diterpenes.Chapter Ⅱ:Synthesis of isocopalane diterpenes with oxygenation patterns at C-17 using the key intermediate 2-16 bearing iodine at the corresponding position as starting material was explored.The desired compound 3-6c was successfully obtained in a yield of 39%.Further synthetic study approaching ent-Spongian-16-oxo-17-al and ent-Isoaplyroseol-14 from 3-6c is under way.