Studies toward Total Synthesis of Non-Aromatic Erythrinan Alkaloids. 7. Synthesis of Cocculolidine Skeleton.
作者:Kunihiko MOHRI、Kimiaki ISOBE、Manabu MAEDA、Taroh TAKEDA、Ryoko OHKUBO、Yoshisuke TSUDA
DOI:10.1248/cpb.46.1872
日期:——
The skeletal structure of cocculolidine (1), a D-nor-erythinan alkaloid, was synthesized as the 8-oxo derivative 2 by several routes via the diester 4 as a key intermediate. One route was an ozonolysis of 14, 15, 17-trimethoxy-8-oxo-erythrinan (3) to directly yield 4 in 63%. The other was the Ce(IV) methanesulfonate oxidation of 16, 17-dimethoxy-8-oxo-erythinan (6) to yield the p-quinone 7 (94%), which was converted to the same diester 4 by ozonolysis and peroxide oxidation (70%). The diester 4 was transformed to the corresponding anhydride 5, which was regioselectively reduced with a bulky borohydride (K-selectride[○!R]) to give the desired lactone 2.
椰油烷(1)是一种 D-去甲赤藓楠生物碱,其骨架结构是以二酯类化合物 4 为关键中间体,通过多种途径合成的 8-氧代衍生物 2。其中一种方法是对 14, 15, 17-三甲氧基-8-氧代赤藓南(3)进行臭氧分解,直接生成 4(63%)。另一种方法是用甲磺酸 Ce(IV) 氧化 16、17-二甲氧基-8-氧代赤藓南 (6),生成对醌 7(94%),对醌 7 通过臭氧分解和过氧化物氧化转化成相同的二酯 4(70%)。二酯 4 转化为相应的酸酐 5,用笨重的硼氢化物(K-selectride[○!R])进行区域选择性还原,得到所需的内酯 2。