Total Synthesis of the Pseudopterane (−)-Kallolide B, the Enantiomer of Natural (+)-Kallolide B
Total Synthesis of the Pseudopterane (−)-Kallolide B, the Enantiomer of Natural (+)-Kallolide B
复制标题
天然 (+)-Kallolide B 的对映异构体准翅 (−)-Kallolide B 的全合成
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
E. Wallace
中科院分区：
文献类型：
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作者：
J. Marshall;Gary S. Bartley;E. Wallace
以 (S)-(-)-紫苏醇 (8) 为起始原料，实现了卡洛内酯 B 的对映体 35 的全合成。通过用H 5 IO 6 然后用CH 2 N 2 处理环氧化物9来实现对酯醛11的氧化裂解。通过 SnCl2 促进 1-溴-2-丁炔加成至醛 11 并随后进行 Swern 氧化而获得的联烯基酮 13 在催化 AgNO3 存在下环化为呋喃 14。衍生的醛 15 与 CBr4−Ph3P 和正丁基锂和 CH2O 进行同系化，得到炔丙醇 17。呋喃 17 (s-BuLi，DMF) 甲酰化，然后 Still−Horner−Emmons 同系化，得到 (Z)-共轭酯 22。将炔丙醇官能团转化为氯化物 23 并进行酯还原 (DIBAL-H)，得到氯醇24，用NaH处理后形成环醚25。醚 25 经历高度非对映选择性的 [2,3]Wittig 环收缩，生成炔丙醇 26。衍生的甲磺酸酯 36 在 CO 和 CO 的作用下转化为联二烯酸酯 37。
A total synthesis of the enantiomer 35 of kallolide B was achieved starting from (S)-(−)-perillyl alcohol (8). Oxidative cleavage to the ester aldehyde 11 was effected by treatment of the epoxide 9 with H5IO6 followed by CH2N2. The allenyl ketone 13, obtained by SnCl2-promoted addition of 1-bromo-2-butyne to aldehyde 11 and subsequent Swern oxidation, cyclized to the furan 14 in the presence of catalytic AgNO3. Homologation of the derived aldehyde 15 with CBr4−Ph3P followed by n-BuLi and CH2O led to the propargylic alcohol 17. Formylation of the furan 17 (s-BuLi, DMF) and then Still−Horner−Emmons homologation yielded the (Z)-conjugated ester 22. Conversion of the propargylic alcohol function to the chloride 23 and ester reduction (DIBAL-H) furnished the chloro alcohol 24, which formed the cyclic ether 25 upon treatment with NaH. Ether 25 underwent a highly diastereoselective [2,3]Wittig ring contraction to the propargylic alcohol 26. The derived mesylate 36 was converted to the allenic ester 37 with CO an...