Polyaromatic Ribbon/Benzofuran Fusion via Consecutive Endo Cyclizations of Enediynes
摘要:
The Sonogashira/5-endo-dig/6-endo-dig cascade fuses a polycyclic aromatic backbone to the electron-rich furan subunit. The transformation proceeds in modest yields as a one-pot reaction. Efficiency of the full cascade is increased by removal of base prior to the addition of gold catalyst. Under these conditions, conversion to the full cascade products is achieved in nearly quantitative yields without purification of the intermediate products. Extension of the cascade toward triynes opens access to benzofuran-fused chrysene derivatives.
Complex Annulations through Silver Carbenoid Intermediate: An Alternative Entry to Transformations of 1,2,3-Triazoles
作者:Yuan Yang、Jiang-Xi Yu、Xuan-Hui Ouyang、Jin-Heng Li
DOI:10.1021/acs.orglett.7b01682
日期:2017.8.4
transformations of N-sulfonyl-4-(2-(ethynyl)aryl)-1,2,3-triazoles with various generated in situ or external nucleophiles by means of silver catalysis for producing diverse functionalized isoquinolines is described. Mechanistically, the reaction is proposed to involve a key silver carbenoid intermediate, thus enabling the formation of multiple chemical bonds via ring opening, N2 extrusion, silver carbenoid
Grignard Reagent/CuI/LiCl-Mediated Stereoselective Cascade Addition/Cyclization of Diynes: A Novel Pathway for the Construction of 1-Methyleneindene Derivatives
作者:De-Yao Li、Yin Wei、Min Shi
DOI:10.1002/chem.201302191
日期:2013.11.11
Diynes containing a cyclopropane group smoothly undergo a novel intramolecular and stereoselective cascade addition/cyclization reaction to produce the corresponding 1‐methyleneindene derivatives in moderate to good yields. This interesting transformation is mediated by Grignard reagent/CuI with LiCl as an additive under mild conditions. The obtained product can easily be further functionalized through
Insights into the Gold-Catalyzed Propargyl Ester Rearrangement/Tandem Cyclization Sequence: Radical versus Gold Catalysis-Myers-Saito- versus Schmittel-Type Cyclization
作者:Eva Rettenmeier、Max M. Hansmann、Alexander Ahrens、Katharina Rübenacker、Tapish Saboo、Joy Massholder、Christian Meier、Matthias Rudolph、Frank Rominger、A. Stephen K. Hashmi
DOI:10.1002/chem.201501725
日期:2015.10.5
of the gold‐catalyzed tandem 1,3‐carboxy migration/allene–enyne cycloisomerization was undertaken. It was found that after the initial allene formation the selectivity of the reaction is strongly influenced by the polarization of the remaining alkyne. Depending on the substitution pattern of the starting diynes, either a Schmittel‐ or a Myers–Saito‐type cyclization was triggered. The 6‐endo‐dig Myers–Saito‐type
Metalla‐aromatics are important complexes that show unique properties owing to their highly conjugated systems, which show Hückel or Möbius aromaticity. Recently, several metalla‐aromatics showing spiro‐aromaticity or σ‐aromaticity have been reported. Herein, we report the isolation of the first cyclopropametallanaphthalenes, in which the metallacyclopropene ring shows σ‐aromaticity and weak hyperconjugative
A One-Pot Method for the Synthesis of Phenylalkynyl-Substituted Terminal Alkynes by Deprotection/Stannylation followed by a Migita–Kosugi–Stille coupling
A practical one-pot approach for the synthesis of arylalkynyl-substituted terminalalkynes has been developed through a deprotection/ stannylation of a phenylethynyl phosphine oxide followed by Migita–Kosugi–Stille coupling, avoiding the longer synthetic route involving repeated deprotection/Sonogashira coupling. Other features of this approach include mild reaction conditions, excellent yields, facile