Pd(II)-Catalyzed One-Step Construction of Cycloalkane-Fused Indoles and Its Application in Formal Synthesis of (±)-Aspidospermidine
摘要:
A highly efficient, redox-free Pd(II)-catalyzed tandem cyclization reaction initiated by intramolecular amino-palladation of alkynes followed by nucleophilic addition to nitrites is developed. This method provides a versatile approach for the synthesis of six- to eight-membered ring-fused indoles in one step and has also shown advantages in the formal synthesis of (+/-)-aspidospermidine.
据报道,氧-炔烃-腈官能团的两个新的水合碳环化反应产生了独特的含氮杂环。在热的1,4-二恶烷中用PtCl 2 / CO / H 2 O长时间加热氧代炔基腈底物,得到2,3-二氢-1 H-吡啶基[1.2 - b ]-异喹啉-4(6 H)-。在该水合反应中,短暂地有效分离出二羰基腈中间体,然后将其进行基于NHC的交叉安息香偶合,得到螺环醇,并进一步与TfOH反应生成螺环[indene-2,2'-哌啶]。-1,6 ′(3 H)-二酮。
Thiocyanate radical mediated dehydration of aldoximes with visible light and air
作者:Yong-Liang Ban、Jian-Ling Dai、Xiao-Ling Jin、Qing-Bao Zhang、Qiang Liu
DOI:10.1039/c9cc05354a
日期:——
We developed a new means of activating aldoximes by an in situ generated thiocyanate radical from ammonium thiocyanate and molecular oxygen at room temperature. With a catalytic amount of organic dye aizenuranine as the photocatalyst, the dehydration of aldoximes proceeds smoothly under visiblelight irradiation, providing a simple to handle, excellent functional group tolerance, and metal-free protocol
Divergent Synthesis of Densely Substituted Arenes and Pyridines via Cyclotrimerization Reactions of Alkynyl Triazenes
作者:Jin-Fay Tan、Carl T. Bormann、Florian G. Perrin、F. Mark Chadwick、Kay Severin、Nicolai Cramer
DOI:10.1021/jacs.9b04111
日期:2019.7.3
aromatic triazenes can be prepared by [2 + 2 + 2] cyclotrimerization reactions of 1-alkynyl triazenes. The Cp*Ru-catalyzed cyclization proceeds well with both simple alkynyl triazenes and tethered 1-diynyl triazenes. Attractively, the methodology can be extended to pyridine synthesis by replacing an alkyne with a nitrile. The reaction is regioselective and yields the sterically more hindered product.
Interruption of Formal Schmidt Rearrangement/Hosomi–Sakurai Reaction of Vinyl Azides with Allyl/Propargylsilanes
作者:Guichun Fang、Zhenhua Liu、Shanshan Cao、Haiyan Yuan、Jingping Zhang、Ling Pan
DOI:10.1021/acs.orglett.8b03062
日期:2018.11.16
An interrupted Schmidt rearrangement/Hosomi–Sakurai reaction of N-tosyl and S-substituted vinyl azides is reported. With BF3·Et2O as a Lewis acid promoter, the denitrogenative fragmentation of vinyl azides facilitates the generation of the N/S-stabilized carbocations, which further undergo nucleophilic addition by allyl/propargylsilanes for C–C bond formation. As a result, a variety of homoallylic/allenylic
Parallel strategies for the synthesis of annulated pyrido[3,4-b]indoles via Rh(I)- and Pd(0)-catalyzed cyclotrimerization
作者:Bianca M. Saliba、Satyam Khanal、Michael A. O'Donnell、Kathryn E. Queenan、Junho Song、Matthew R. Gentile、Seann P. Mulcahy
DOI:10.1016/j.tetlet.2018.10.050
日期:2018.12
Two different pathways for the synthesis of annulated pyrido[3,4-b]indoles are reported using metal-catalyzed cyclotrimerization reactions. A stepwise process using Rh(I)-catalysis in the final step of the synthesis and a multicomponent, tandem catalytic approach using Pd(0)-catalysis both lead to complex nitrogen-containing heterocycles in good yields. Substituent effects are investigated for both
使用金属催化的环三聚反应已报道了两种合成环式吡啶并[3,4- b ]吲哚的不同途径。在合成的最后一步中使用Rh(I)催化的分步过程和使用Pd(0)催化的多组分串联催化方法均会以高收率产生复杂的含氮杂环。研究了两种途径的取代基效应,表明Pd(0)催化的方法对吸电子基团更敏感。
Concise Synthesis of Annulated Pyrido[3,4-<i>b</i>]indoles via Rh(I)-Catalyzed Cyclization
作者:Jonathan G. Varelas、Satyam Khanal、Michael A. O’Donnell、Seann P. Mulcahy
DOI:10.1021/acs.orglett.5b02807
日期:2015.11.6
The synthesis of pyridines bearing multiple ring fusions poses a considerable challenge for organic chemists. To address this problem, we describe the synthesis of a small library of pyrido[3,4-b]indoles via an efficient, five-step sequence. The key transformation is a Rh(I)-catalyzed [2 + 2 + 2] cyclization that forms three rings in one reaction flask. Our method is high yielding, accommodates a variety
带有多个环稠合的吡啶的合成对有机化学家提出了相当大的挑战。为了解决这个问题,我们描述了通过高效的五步序列合成一个小的吡啶并[3,4- b ]吲哚文库。关键的转化是Rh(I)催化的[2 + 2 + 2]环化反应,该环化反应在一个反应瓶中形成三个环。我们的方法收率高,可容纳各种官能团,并且随着环尺寸的增加,无熵成本。