A Facile Entry into Naphthopyran Quinones via an Annelation Reaction of Levoglucosenone. The Total Synthesis of (−)-Hongconin<sup>1</sup>
作者:John S. Swenton、John N. Freskos、Peter Dalidowicz、Michael L. Kerns
DOI:10.1021/jo951607e
日期:1996.1.1
The annelation reactions of levoglucosenone, prepared by pyrolysis of paper, with 3-cyano-1(3H)-isobenzofuranone and 3-cyano-5-methoxy-1(3H)-isobenzofuranone have been studied. Reductive ring-opening of the annelation products with zinc/copper couple and subsequent chemical transformations provide a facile entry into the naphthopyran quinone ring system. Standard chemical transformations of the annelation
研究了纸热解制备的左葡糖醛酮与3-氰基-1(3H)-异苯并呋喃酮和3-氰基-5-甲氧基-1(3H)-异苯并呋喃酮的脱环反应。锌/铜对偶合产物的还原性开环和随后的化学转化为萘并吡喃醌环系统提供了便捷的入口。从3-氰基-5-甲氧基-1(3H)-异苯并呋喃酮和左旋葡糖醛酮的缩合产物进行标准化学转化,得到(1R)-5,9,10-三甲氧基-1-甲基-1H-萘[2,3-c ] pyran-4(3H)-one。该化合物的烯醇锂与氧气进行有趣的且潜在有用的反应,得到(3R)-4,5,9-三甲氧基-3-甲基萘[2,3-c]呋喃-1(3H)-one。如果严格排除氧气,在10当量的DMPU存在下,使用10当量的碘甲烷可以高收率进行烯醇盐的甲基化。该化学过程最终完成了从左葡糖醛酮分六步合成(-)-hongconin的过程。