A novel visible-light-catalyzed tandem radical addition/ 1,5-hydrogen atom transfer/cyclization cascade of 2-alkynylarylethers with sulfonyl chlorides in 2-methyltetrahydrofuran was developed under photocatalyst-and additive-free conditions. This reaction relies on unique energy transfer and solvent-radical relay strategies to generate sulfonyl radicals for the preparation of a series of sulfonylfunctionalized dihydrobenzofurans in moderate to high yields catalyzed by visible light or solar radiation.
The construction of all-carbon quaternary centers, especially those containing an alkyne-substituted framework, represents an important challenge in organic synthesis. Here we present a novel Fe-catalyzed selective formal insertion of diazo compounds into C(sp)−C(sp 3 ) bonds of propargyl alcohols under mild conditions that enables the streamlined construction of alkynesubstituted all-carbon quaternary centers. This unique strategy starts with in situ generation of an ester group in the presence of carboxylic acids, followed by insertion of metal-carbene into C(sp)− C(sp 3 ) bonds, which may open up a new reaction mode for exploring metal-carbene insertion into acyclic C−C bonds.
The radical tandem bicyclization provides a novel approach for the preparation of complex polycyclic compounds in synthetic chemistry. Herein, we first described a tandem radical bicyclization reaction of CN-containing 1,6-enynes...
We describe a method for radical cyclization of N-methacryloyl-2-arylbenzoimidazoles with nitriles, ketones, and tert-butyl nitrite (TBN) for the preparation of benzimidazo[2,1-a]isoquinolin-6(5H)-ones with the advantage of mild reaction conditions, excellent functional group compatibility and broad substrate scope. The present strategy has favorable characteristics: (1) the use of cheap metal catalysis; (2) N-radical initiated cyclization of N-methacryloyl-2-arylbenzoimidazoles; (3) rare example of radical C(sp3)–H functionalization in this cyclization.
A novel cyclization/hydrolysis of 1,5-enenitriles for the synthesis of valuable pyrrolidine-2,4-diones in aqueous phase using I2 as the catalyst and tert-butyl hydroperoxide (TBHP) as the oxidant is reported. In the...
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