Umpolung Reactivity of Indole through Gold Catalysis

Abstract

Electrophilic indole? Indoles, which are typically nucleophilic, can be made electrophilic through gold catalysis. By using an ortho‐azido group to deliver a nitrene intramolecularly, an arylalkyne is converted into a gold carbene intermediate containing an indole skeleton that is highly electrophilic at the 3‐position. A range of functionalized indoles is readily accessed by utilizing this strategy.

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 …”

“…8,116.1,120.8,125.1,125.8,128.3,128.8,128.9,130.1,130.3,134.4,138.3,147.4;IR (neat) 4,19.0,21.7,29.7,74.1,99.9,125.5,126.3,127.7,128.9,129.1,129.4,131.0,132.0,133.9,134.5,136.5,139.6;IR (neat) 2, 96.7, 115.5, 120.6, 121.7, 125.1, 125.8, 128.4, 128.6, 128.9, 129.2, 129.3, 130.1, 131.5, 134.3, 135.3, 138.3, 147.5;IR (neat) ν: 3447, 2922IR (neat) ν: 3447, , 1497IR (neat) ν: 3447, , 1240IR (neat) ν: 3447, , 1023 4,85.1,95.0,114.2,120.9,122.3,125.5,125.7,128.2,128.5,128.8,128.9,129.8,130.5,131.4,133.2,137.5,140.4,147.2;…”

Au‐ and Pt‐Catalyzed CH Activation/Functionalizations for the Synthesis of Heterocycles

“…Deuterium labeling and kinetic isotope effect studies along with the isolation of alkyl gold intermediates strongly support an electrophilic aromatic substitution for the C-H functionalization and a subsequent inner-sphere concerted reductive elimination for the C(sp 2 )-C(sp 3 ) bond formation. In 2011, a gold-catalyzed one-pot reaction of ortho-azidophenylalkyne 42 with electron-rich aromatics and heteroaromatics was independently developed by Zhang and Gagosz (Scheme 12.21) [25], which gave functional indoles 43a in good to excellent yields. This one-pot reaction consists of an intramolecular C-N formation and intermolecular aryl C(sp 2 )-H functionalization/C-C bondforming procedure.…”

“…The key intermediate pyrrolidine 53 in the total synthesis of flinderoles B and C could be efficiently constructed as a single diastereomer via Au-catalyzed intramolecular hydroarylation of a pendant allene 52, which was prepared from commercially available tryptophol 51. 12 25. Application of Au-catalyzed hydroarylation in the synthesis of flinderoles B and C.…”

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.…”