Facile access to 2,2-diaryl 2<i>H</i>-chromenes through a palladium-catalyzed cascade reaction of <i>ortho</i>-vinyl bromobenzenes with <i>N</i>-tosylhydrazones
作者:Heng Zhang、Yinghua Yu、Xueliang Huang
DOI:10.1039/d0ob00978d
日期:——
A palladium-catalyzed cascade reaction of ortho-vinyl bromobenzenes with N-tosylhydrazones has been developed, which provides a facile approach to 2,2-disubstituted 2H-chromenes. The migration of palladium from the aryl to vinyl position is crucial, as the in situ produced vinyl palladium intermediate could further react with diazocompounds to generate the reactive species for the sequential annulation
Direct Synthesis of 2-Methylbenzofurans from Calcium Carbide and Salicylaldehyde <i>p</i>-Tosylhydrazones
作者:Rugang Fu、Zheng Li
DOI:10.1021/acs.orglett.8b00676
日期:2018.4.20
A new methodology for the construction of methyl-substituted benzofuran rings from the reactions of calcium carbide with salicylaldehyde p-tosylhydrazones/2-hydroxyacetophenone p-tosylhydrazones is described. Various 2-methylbenzofurans and 2,3-dimethylbenzofurans could be obtained in satisfactory yield by using a cuprous chloride catalyst. The advantages of this protocol include the use of a readily
A copper(<scp>ii</scp>) perchlorate-promoted tandem reaction of internal alkynol and salicyl N-tosylhydrazone: direct access to isochromeno[3,4-b]chromene
作者:Hai Xiao Siyang、Xu Rui Wu、Xiao Yue Ji、Xin Yan Wu、Pei Nian Liu
DOI:10.1039/c4cc02862g
日期:——
A copper(ii) perchlorate-promoted tandem reaction of internal alkynol and salicyl N-tosylhydrazone provides a novel, concise method for constructing isochromeno[3,4-b]chromene in 35-94% yields. The tandem reaction involves cycloisomerization, formal [4+2] cycloaddition and an elimination process.
Palladium-Catalyzed Tandem Reaction of Alkyne-Based Aryl Iodides and Salicyl<i>N</i>-Tosylhydrazones to Construct the Spiro[benzofuran-3,2′-chromene] Skeleton
作者:Xue Song Shang、Nian Tai Li、Deng Yuan Li、Pei Nian Liu
DOI:10.1002/adsc.201501150
日期:2016.5.19
aryl iodides and salicyl N‐tosylhydrazones has been achieved to afford a series of compounds containing the novel spiro[benzofuran‐3,2′‐chromene] scaffold in moderate to good yields. This efficient catalytic reaction, which tolerates various functional groups, combines alkyne‐based 5‐exo‐dig cyclization, palladium(II) carbene migratory insertion and intramolecular cyclization, generating three new bonds
Palladium-Catalyzed Tandem Carbene Migratory Insertion and Intramolecular Cyclization: Synthesis of Chromeno[4,3-<i>b</i>]chromene Compounds
作者:Xue Song Shang、Nian Tai Li、Hai Xiao Siyang、Pei Nian Liu
DOI:10.1021/acs.joc.5b00500
日期:2015.5.1
Chromeno[4,3-b]chromene is a ubiquitous structural motif found in various pharmaceuticals and biologically active compounds. A concise palladium-catalyzed reaction of vinyl iodides and salicyl N-tosylhydrazones has been achieved to afford a series of compounds containing the chromeno[4,3-b]chromene scaffold in moderate to high yield. This tandem reaction involves palladium(II) carbene migratory insertion and intramolecular cyclization assisted by an O nucleophile and tolerates various functional groups.