Total syntheses of gerberinol I and the pterophyllins 2 and 4 using the Casnati–Skattebøl reaction under different conditions
作者:Jorgelina L. Pergomet、Andrea B. J. Bracca、Teodoro S. Kaufman
DOI:10.1039/c7ob01471f
日期:——
The concise and efficient total syntheses of the naturally-occurring coumarin derivatives gerberinol I, and the pterophyllins 2 and 4, from 5-methyl-4-hydroxycoumarin as a common precursor employing different Casnati-Skattebøl reaction conditions, are reported. The synthesis of the key intermediate coumarin was achieved by the organocatalytic condensation of acetylacetone and crotonaldehyde followed
据报道,自然而然的香豆素衍生物Gerberinol I以及来自5甲基-4-羟基香豆素的蝶呤类固醇2和4,采用不同的Casnati-Skattebøl反应条件进行了简单,有效的合成。关键中间体香豆素的合成是通过乙酰丙酮和巴豆醛的有机催化缩合,然后进行LiCl辅助的环化,CuCl2促进的芳构化和最终的Et2CO3介导的环化。在高温条件下,Casnati-Skattebøl甲酰化反应可得到小ol醇I,而较温和的条件则可导致不稳定的3-甲酰基-4-羟基香豆素衍生物,将其经碱性氧化铝介导的一锅O-烷基化与氯丙酮和分子内醛醇缩合反应生成提供叶绿素4。