Gold‐Catalyzed Transformation of 2‐Alkynyl Arylazides: Efficient Access to the Valuable Pseudoindoxyl and Indolyl Frameworks

Abstract

An element of surprise: A series of functionalized 2‐alkynyl arylazides has beed converted into 3‐substituted indoles or 2,2‐disubstituted indolin‐3‐ones in the presence of a gold(I) complex. Various oxygen or aryl nucleophiles can be used in this process to trap the intermediate α‐imino gold carbene. The structural motifs of the products are found in a large variety of biologically active compounds and natural products.

Gold-Catalyzed Tandem Reactions of 2-Alkynyl Arylazides: Efficient Access to 3-Alkynyl Indoles

“…2005 年, Toste 课题组 [6] 发表了第一篇关于金催化的 叠氮与炔的 Schmidt 反应合成吡咯衍生物, 这类反应利 用均相金催化炔基叠氮化合物形成 α-亚胺金卡宾, 被亲 核试剂捕捉合成含氮杂环化合物. 直到最近国外内发表 的关于对 α-亚胺金卡宾捕捉的文章还是不多 [7] , 代表性 的研究主要有 Zhang [8] 和 Gagosz [9] 两个课题组同时报道 了 α-亚胺金卡宾被各种亲核试剂捕捉合成吲哚衍生物 的反应, 以及最近 Gong 课题组 [10] 发表的用炔丙基醇捕 图式 1 设计捕捉 α-亚胺金卡宾 Scheme 1 Synthetic design for the trapping of α-imino gold carbene 1 结果与讨论 …”

One‐Pot and Regioselective Gold‐Catalyzed Synthesis of 2‐Imidazolyl‐1‐pyrazolylbenzenes from 1‐Propargyl‐1H‐benzotriazoles, Alkynes and Nitriles through α‐Imino Gold(I) Carbene Complexes

“…[6] Since that seminal contribution, the most extended procedure for the access to -imino gold carbenes as intermediates is based on intramolecular transformations of azides with goldactivated alkynes. [7] In addition, a few intermolecular approaches have been carried out, although they require the use of heteroatom-polarized alkynes as ynamides. [8] The use of other nucleophilic nitrenoids as pyridine-N-aminides [9] or 2H-azirine derivatives, [10] has recently emerged as an elegant alternative to azides, however these methodologies present similar limitations in terms of intermolecular reactivity.…”

“…Due to the high attention received by azides in their reaction with gold-activated alkynes, [6][7][8] we decided to explore the reactivity of triazapentalenes 2 with alkynes in the presence of a gold catalyst. However, the treatment of the dipolar compound 2a with phenylacetylene 3a, in acetonitrile at 60ºC, in the presence of a NHC gold(I) complex (IPrAuNTf 2 (5 mol%)), resulted in no positive reaction.…”

Gold-Catalyzed Tandem Reactions of 2-Alkynyl Arylazides and Carboxylic Acids for the Synthesis of 1H-Indol-3-yl Esters

“…在均相金催化领域的发展过程中, 金催化炔基叠 氮化合物形成 α-亚胺金卡宾中间体, 接着被各种亲核试 剂捕捉形成含氮杂环化合物的研究是一个十分重要的 发展方向 [5] . 2011 年, Zhang [6] 和 Gagosz [7] 两个课题组同 时报道了金催化 2-炔基叠氮化合物被各种亲核试剂捕 捉合成吲哚衍生物的反应, 但在所有亲核试剂中没有尝 试羧酸衍生物, 可能是因为羧酸是一种相对较弱的亲核 试剂, 不利于捕捉生成的金卡宾. 最近, 我们课题组在 研究 α-亚胺金卡宾反应中发现, 当羧酸为溶剂时羧酸可 以有效地捕捉生成的金卡宾, 从而为 3-吲哚酯衍生物的 合成提供了一种简单、高效的方法.…”