基于高选择性碳正离子串联环化反应的Drimane环系合成

Rapid Synthesis of Drimane Skeleton via Selective Cationic Polyene Cyclization

Drimane型混源倍半萜是一类具有多种生物活性的重要天然产物。分别以(2E,6E)-金合欢醇和(2Z,6E)-金合欢醇为原料,经酯化、环氧化、碳正离子串联环化3步反应高选择性地构建出8-hydroxydrimane骨架和具有环内双键的Drimane骨架,并经区域选择性消除后得到具有环外双键的Drimane骨架,其结构经1HNMR、13CNMR、COSY、NOESY和MS确证。为具有Drimane骨架的天然产物全合成提供了一种高选择性的合成方法。

A highly regioselective and diastereoselective cationic polyene cyclization cascade was developed for the synthesis of Drimane-type sesquiterpenoids,which represented an array of important natural products with diverse biological activities such as anticancer,anti-HIV,and antifungal.The reaction sequence features a unique cyclization precursor using 3-oxobutanoyl as the protection group which can lead to diastereoselective cyclization and regioselective elimination.The work achieved highly selective synthesis of 8-hydroxydrimane skeleton and endo/exo double-bond Drimane skeletons.The products of the above reaction sequence were unambiguously confirmed by 1HNMR,13CNMR,COSY,NOESY and MS.The highly selective synthesis method could be used for the total synthesis of natural products with Drimaneskeleton.