A variety of pyrrolo[3,4-c]pyrazole derivatives
from readily available aldehyde hydrazones and maleimides via direct
oxidative coupling under radical cascade reaction have been reported.
This method offers satisfactory chemical yields and good functional
group compatibility. Moreover, this practical approach is catalyzed
by CuCl utilizing air as the oxidant and some control experiments
were performed to elaborate the mechanism.
A reductive radical relay strategy for the construction of fused benzo[e]isoindole-1,3,5-trione through a reaction of α-bromo ketones with maleimides in the presence of Ir(ppy) 3 under visible-light irradiation is described. The protocol employs very mild reaction conditions and offers satisfactory yields. Moreover, the reaction proceeds through a cascade C(sp 3 )−Br/C(sp 2 )−H functionalization, double C−C bond formation, and oxidative aromatization sequence.
A designed method for the preparation of 3-aminomethylated maleimides via Morita−Baylis−Hillman (MBH) reaction was developed. This phosphine-catalyzed coupling adopted maleimides and 1,3,5-triazinanes as the substrate, giving a series of 3-aminomethylated maleimide derivatives with a double bond retained on the maleimide ring in 41−90% yield. Acylation, isomerization, and Michael addition of the obtained products demonstrated the synthetic application of the present protocol. The results of control experiments indicated that phosphorus ylide formation and elimination take place during the reaction pathway.
A regioselective
synthesis of polysubstituted dihydropyrazoles
and pyrazoles through an iodine-catalyzed oxidative cyclization strategy
of aldehyde hydrazones with electron-deficient olefins is described.
The protocol adopts very mild reaction conditions and provides desirable
yields. The reaction is supposed to proceed via a cascade C–H
functionalization, C–N bond formation, and oxidation sequential
processes. The overall simplicity and regioselectivity of the catalytic
system make this approach a valuable and step-economical tool to construct
a C–C bond for the synthesis of Mefenpyr-Diethyl.
An
efficient annulation method for the synthesis of polysubstituted
dihydrofurans from 1,3-dicarbonyl compounds and maleimides is described.
The reactions can afford furo[2,3-c]pyrrole derivatives
with satisfactory yields. The developed strategy realizes the direct
oxidative double C(sp3)–H functionalization in the
presence of copper(I) salts and 2-(tert-butylperoxy)-2-methylpropane.
Meanwhile, this protocol features a mild reaction condition and simple
catalytic system. A reaction mechanism involving a single electron
oxidation is also proposed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.