The Revised Structure of Dispermol and Total Synthesis of Maytenoquinone, Dispermol, and Dispermone
作者:Takashi Matsumoto、Taishi Ohmura、Shuji Usui
DOI:10.1246/bcsj.52.1957
日期:1979.7
Condensation of β-cyclocitral with 2-isopropyl-3,4-dimethoxybenzyl chloride afforded an alcohol (15) which was converted into (±)-12,13-dimethoxytotara-8,11,13-trien-6-one (18). Demethylation of (±)-18 followed by air oxidation gave (±)-maytenoquinone. Reductive cleavage of the hydroxyl group in (±)-15 produced a phenethyl derivative which was cyclized to give (±)-12,13-dimethoxytotara-8,11,13-triene (23) and its cis-isomer (24). Oxidation of (±)-23 with chromium trioxide, followed by demethylation of the resulting 7-oxo compound (25), afforded (±)-dispermone. The Wittig reaction of (R)-(−)-α-cyclocitral with 2-isopropyl-3,4-dimethoxybenzyltriphenylphosphonium chloride yielded a styrene derivative. This was partially hydrogenated and then cyclized to give (+)-23 and (−)-24. The trans-isomer (23) was converted into (−)-dispermone (3) via (−)-25 and also partially demethylated to (+)-12-methoxytotara-8,11,13-trien-13-ol (2), the proposed structure for dispermol. Since the synthetic (+)-2 was not identical with the natural compound, (−)-3 was then converted into (+)-13-methoxytotara-8,11,13-trien-12-ol, which was identical with natural dispermol. (−)-25 was also converted into (+)-maytenoquinone.
β-环柠檬醛与 2-异丙基-3,4-二甲氧基苄基氯缩合生成醇(15),然后转化为(±)-12,13-二甲氧基托塔拉-8,11,13-三烯-6-酮(18)。(±)-18脱甲基后经空气氧化得到(±)-美替诺醌。(±)-15中羟基的还原裂解产生了苯乙基衍生物,环化后得到(±)-12,13-二甲氧基托塔拉-8,11,13-三烯(23)及其顺式异构体(24)。用三氧化铬氧化(±)-23,然后将生成的 7-氧代化合物 (25) 去甲基化,得到了(±)-二苯甲酮。(R)-(-)-α-环柠檬醛与 2-异丙基-3,4-二甲氧基苄基三苯基氯化鏻的 Wittig 反应生成苯乙烯衍生物。对其进行部分氢化,然后环化得到 (+)-23 和 (-)-24。反式异构体(23)通过(-)-25 转化为(-)-二苯甲酮(3),并部分去甲基化为(+)-12-甲氧基托塔拉-8,11,13-三烯-13-醇(2),这是二苯甲醇的拟议结构。由于合成的(+)-2 与天然化合物不完全相同,(-)-3 随后被转化为(+)-13-甲氧基土荆皮-8,11,13-三烯-12-醇,这与天然二香豌豆酚完全相同。(-)-25也转化成了(+)-maytenoquinone。