Studies of the Furan-Terminated Cationic Cyclization: A Serendipidious Synthesis of Pallescensin A
作者:Udo Lange、Siegfried Blechert
DOI:10.1055/s-1995-4052
日期:1995.9
The furan-terminated cationic cyclization reaction of 4-(2-furan-2-yl-2-methoxyethyl)-3,5,5-trimethylcyclohex-2-enol (3) yielded 6,6,9a-trimethyl-4,5,5a,6,7,9a-hexahydronaphtho[1,2-b]furan-4-ol (9b) in a Pictet-Spengler-like reaction thereby giving a good insight into the possible mechanism of this β-cyclization. Alcohol 9b was converted into 6,6,9a-trimethyl-7,9a-dihydro-6H-naphtho[1,2-b]furan-4-one (12), thus, completing a formal total synthesis of pallescensin A (13).
4-(2-呋喃-2-基-2-甲氧基乙基)-3,5,5-三甲基环己-2-烯醇 (3) 的呋喃端阳离子环化反应生成了 6,6,9a-三甲基-4,5,5a,6,7,9a-六氢萘并[1,2-b]呋喃-4-醇 (9b),该反应类似于 Pictet-Spengler 反应,从而使人们对这种δ-环化的可能机理有了很好的了解。醇 9b 被转化为 6,6,9a-三甲基-7,9a-二氢-6H-萘并[1,2-b]呋喃-4-酮 (12),从而完成了苍术素 A (13) 的正式全合成。