Convergent Synthesis of the E‘FGH Ring Fragment of Ciguatoxin 1B via an Acetylene Cobalt Complex Strategy
作者:Shigeyuki Takai、Naotaka Sawada、Minoru Isobe
DOI:10.1021/jo034021y
日期:2003.4.1
A convergent synthesis of the E'FGH ring fragment 28 of ciguatoxin 1B, a principal toxin causing widespread seafood poisonings "ciguatera", has been accomplished through (i) coupling between the E' ring-acetylide 9 and the H ring-aldehyde 20, (ii) stereoselective F ring cyclization via an acetylene cobalt complex, (iii) conversion to a carbonyl function under high-pressure hydrogenation, and (iv) reductive
已经通过(i)E'环乙炔化物9和H环醛20之间的偶合完成了瓜瓜毒素1B的E'FGH环片段28的会聚合成,瓜瓜毒素1B是引起广泛的海鲜中毒的“瓜瓜”的主要毒素。 (ii)经由乙炔钴络合物的立体选择性F环环化,(iii)在高压氢化下转化为羰基官能团,和(iv)还原性羟基酮环化以构建G环。在室温下对28进行的(1)H NMR分析中,由于FG环的构象变化缓慢,观察到了相当大的扩宽现象,这是天然雪茄毒素1B的报道。当在-20摄氏度于吡啶中进行测量时,28的光谱显示出两种构象异构体(UP和DOWN构象异构体)的3.5:1混合物。