The Cs2CO3-mediated formal (4 + 2) cascade annulation strategy for the synthesis of 2-aminoquinoxalines has been developed using D–A cyclopropanes and o-benzenediamines as the substrates. The protocol provides an efficient method of accessing a broad range of 2-aminoquinoxaline derivatives in good to excellent yields with good functional-group tolerance.
Organic selenium compounds are important molecules with a wide range of applications in pharmaceuticals, organic materials, catalysis, and other fields. Herein, we report the synthesis of α-selenomethylketones through the reaction of vinyl azides with arylselenols and benzylselenol. This protocol has the advantages of releasing only nitrogen as a benign byproduct, using air as an environmentally friendly initiator, a very short duration, mild reaction conditions, and broad substrate compatibility. The results of exploratory studies show that oxygen in the air is used as the initiator to promote this radical cascade reaction.
An efficient one-pot three-component [3 + 2]-cycloaddition reaction of azomethine ylides, generated in situ from isatins and azetidine-2-carboxylic acid, with different maleimides and itaconimides has been investigated. These reactions afford the corresponding spiro and dispiro[1-azabicyclo[3.2.0]heptanes] in moderate to high yields (up to 93%) with moderate to excellent diastereoselectivities and excellent regioselectivities under mild conditions. The method provides a simple route to the stereoselective synthesis of new polyheterocyclic systems such as 3-spiro[1-azabicyclo[3.2.0]heptane]oxindoles spiro-conjugated or fused to a succinimide moiety. The observed diastereo- and regioselectivity of cycloaddition reactions is reasoned by DFT studies. The antiproliferative effect of the synthesized compounds against cancer cell lines was assessed.
Herein, we present an acid- and base-mediated approach for ring opening of donor–acceptor cyclopropanes (DACs) followed by (3+2) annulation, yielding biologically relevant gem-difluorinated cyclopentenes via α,α-difluoroketone scaffolds. Fluorinated rings are essential building blocks in drug discovery and materials research. This methodology has a broad substrate scope, is scalable, and provides a practical synthetic route to obtain value-added fluorinated compounds.
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