Substrate-controlled reactions have been developed for the synthesis of spirocyclopropylpyrazolones and bicyclic 4,5-dihydropyrazoles from 1,2-diaza-1,3-dienes and sulfur ylides. These protocols were carried out under mild reaction conditions without any additives in generally moderate to good yields. Plausible mechanisms for the transformations were proposed.
Sulfur Ylide Initiated [4 + 1]/[4 + 2] Annulation Reactions: A One-Pot Approach to Dibenzofuran Acrylate Derivatives
作者:Jiaan Shao、Wenteng Chen、Zhimin Ying、Shuangrong Liu、Feng Luo、Lili Ou
DOI:10.1021/acs.orglett.9b02260
日期:2019.8.16
A one-pot approach has been developed for the synthesis of polysubstituted dibenzofuran acrylate derivatives from (E)-2-(2-nitrovinyl)phenols, sulfur ylides, and alkynes. This protocol was carried out under mild reaction condition without any precious catalysts in generally moderate to good yields. Additionally, a plausible mechanism for the transformation was proposed.
Mechanistic Studies on a Cooperative NHC Organocatalysis/Palladium Catalysis System: Uncovering Significant Lessons for Mixed Chiral Pd(NHC)(PR<sub>3</sub>) Catalyst Design
作者:Chang Guo、Daniel Janssen-Müller、Mirco Fleige、Andreas Lerchen、Constantin G. Daniliuc、Frank Glorius
DOI:10.1021/jacs.7b00462
日期:2017.3.29
detailed investigation of the catalytically active palladiumspecies pointed toward a dual role of the NHC acting as an organocatalyst and forming a novel mixed ligand Pd/NHC/phosphine complex. The catalytically active Pd/NHC/phosphine complex represents a new class of chiralpalladium catalyst. Remarkably, phosphine plays a crucial role in this transformation. These complexes could be characterized by
A visible light photoredox-catalyzed carbon radical-mediated strategy for in situ formation of ortho-quinone methides from 2-vinyl phenols towards 2,3-dihydrobenzofuran synthesis is described.
Unusual Fluorescent Properties of 3,4,6-Triphenyl-α-pyrones
作者:Keisuke Hirano、Satoshi Minakata、Mitsuo Komatsu
DOI:10.1246/cl.2001.8
日期:2001.1
Novel fluorophores, 3,4,6-triphenyl-α-pyrone derivatives, were synthesized and their spectroscopic properties have been investigated. In the solid state they show intense greenish-yellow fluorescence, but not in solution. It is concluded that the 6-phenyl group is fixed at an angle of about 26° to the pyrone plane in the solid state by molecular packing and this fixation is required for this unique fluorescent property.