The synthesis of 9-<i>O</i>
-Methylpaepalantine and Dehydroxanthomegnin: Related Isocoumarin-Containing Natural Products
作者:Jimmy E. Y. Sumani、Kennedy J. Ngwira、Andreas Lemmerer、Charles B. de Koning
DOI:10.1002/ejoc.201801595
日期:2019.2.7
A key step in the total synthesis of two aromatic isocoumarin‐containing products, 9‐O‐methylpaepalantine and 5‐methoxy‐3,4‐dehydrosemixanthomegnin is a Wacker‐mediated ring closure. For example, expoure of 3‐allyl‐1,4,5,6,8‐pentamethoxynaphthalene‐2‐carboxylic acid to catalytic PdCl2, CuCl2 and O2 afforded 5,7,9,10‐tetramethoxy‐3‐methyl‐1H‐benzo[g]isochromen‐1‐one in 72 % yield.
Wacker介导的闭环是两种含芳香异香豆素的产物(9 - O-甲基庚烷和5-甲氧基-3,4-脱氢分解胶原)的总合成中的关键步骤。例如,将3-烯丙基-1,4,5,6,8-五甲氧基萘-2-羧酸催化分解为PdCl 2,CuCl 2和O 2可得到5,7,9,10-四甲氧基-3-甲基- 1 H-苯并[ g ]异氰酸酯-1-酮,产率为72%。