Gold‐Catalyzed Carbocyclization of Phenols with a Terminal Alkyne via an Intramolecular ipso‐Friedel–Crafts Alkenylation

Abstract

Abstract:We have developed a novel synthetic method to furnish spiroA C H T U N G T R E N N U N G [4.5]cyclohexadienones using an gold-catalyzed carbocyclization of phenols with a terminal alkyne via an intramolecular ipsoFriedel-Crafts alkenylation. Using 2-5 mol% of gold catalyst, 1 equiv. of methanesulfonic acid, and 1 equiv. of 2,6-di-tert-butylpyridine, a variety of spiroA C H T U N G T R E N N U N G [4.5]cyclohexadienone derivatives with an exocyclic olefin unit was obtained in good to excellent yields. The divergent synthesis of dihydronaphthalene derivatives was also examined based on the newly developed gold catalysis.

Recent Progress on Gold-catalyzed Dearomatization Reactions

“…在金催化 C-C 不饱和键氢-官能团化反应中除了 吲哚衍生物作为亲核试剂以外, 苯酚衍生物也能作为亲 核 试 剂 实 现 金 催 化 苯 酚 的 去 芳 构 化 反 应 . 2014 年 , Hamada 小组 [26] 报道了第一例金催化的分子内苯酚和炔 图式 13 基于金催化环化反应的(±)-strictamine 的形式全合成 Scheme 13 Formal total synthesis of (±)-strictamine based on a gold-catalyzed cyclization 图式 14 金催化 2-炔丙基-β-四氢咔唑的扩环和螺环化反应 Scheme 14 Gold-catalyzed ring expansion and spirocyclization of 2-propargyl-β-tetrahydrocarbolines 烃环化去芳构化反应, 生成有用的螺 [ [32] .…”

Palladium(0)‐Catalyzed Intermolecular Carbocyclization of (1,n)‐Diynes and Bromophenols: An Efficient Route to Tricyclic Scaffolds

“…[4] Along with the earlier studies on the dearomatization of indoles [5] and anilines, [6] recent seminal reports by the groups of Hamada, [7] You, [8] Buchwald, [9] Feringa, [10] and Tang [11] have demonstrated that several spirocyclic and fused ring scaffolds could be obtained by transition-metal-catalyzed dearomative cyclizationso f phenol-derived precursors in an intramolecular fashion by the formation of one CÀCb ond. Remarkably,t ransition-metal-catalyzed dearomatization reactions of phenols and naphthols have served as an extraordinarily potent tool for generating some three-dimensional structures which are either difficult or impossible to form by conventional means.…”

“…Remarkably,t ransition-metal-catalyzed dearomatization reactions of phenols and naphthols have served as an extraordinarily potent tool for generating some three-dimensional structures which are either difficult or impossible to form by conventional means. [4] Along with the earlier studies on the dearomatization of indoles [5] and anilines, [6] recent seminal reports by the groups of Hamada, [7] You, [8] Buchwald, [9] Feringa, [10] and Tang [11] have demonstrated that several spirocyclic and fused ring scaffolds could be obtained by transition-metal-catalyzed dearomative cyclizationso f phenol-derived precursors in an intramolecular fashion by the formation of one CÀCb ond. Notwithstanding these excellent examples,t here is ac ompelling need to develop more economical intermolecular cyclization processes with simpler phenol substrates which do not require costly multistep syntheses.…”

Gold‐Catalyzed Intramolecular Dearomatization of Phenols with Allenoates for the Synthesis of Spirocyclohexadienones

“…However, there are relatively few publications on the investigation of gold catalysis in dearomatization reactions compared to other transition metals such as palladium and iridium . In 2014, Hamada and co‐workers reported a gold‐catalyzed carbocyclization of phenols with a terminal alkyne, and then You's group also realized the dearomatization of naphthols with a terminal alkyne under similar conditions in 2016 (Scheme A) . Inspired by these findings, we proposed that the efficient dearomatization of phenols with a terminal allene catalyzed by Au(I) would be an ideal approach for preparing related spirocyclohexadienones (Scheme B).…”