Biomimetic Synthesis of Natural and âUnnaturalâ Lignans by Oxidative Coupling of Caffeic Esters
作者:Carmelo Daquino、Antonio Rescifina、Carmela Spatafora、Corrado Tringali
DOI:10.1002/ejoc.200900804
日期:2009.12
The metal-mediated oxidative coupling of caffeic acid esters has been employed in the biomimetic synthesis of dimeric lignans and neolignans. Phenethyl and methyl caffeate esters were used as substrates and MnO2, Mn(OAc)3 and Ag2O as oxidative coupling agents. The manganese-mediated reactions afforded in good yields the unusual benzo[kl]xanthene lignans 6 and 15 as the major products accompanied by
金属介导的咖啡酸酯氧化偶联已被用于二聚木脂素和新木脂素的仿生合成。苯乙酯和咖啡酸甲酯用作底物,MnO2、Mn(OAc)3 和Ag2O 用作氧化偶联剂。锰介导的反应产生了不寻常的苯并 [kl] 呫吨木脂素 6 和 15 作为主要产物,伴随着少量的芳基二氢萘木脂素 (±)-7 和 (±)-16。当使用 Ag2O 时,新木脂素 (±)-17 是主要产物。这种仿生途径也用于获得天然苯并[kl]呫吨木脂素rufescidride (9) 和mongolicumin A (10)。还进行了偶联反应的计算研究。 (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)