A furfuryl cation induced three‐component thioesterification reaction between thiols, 5‐bromo‐2‐furylcarbinols and azides is reported. This metal‐free method relies on the acetyl chloride/HFIP‐mediated cascade formal [3+2] cycloaddition/ring‐opening/thioesterification, which allows the efficient construction of a series of complex triazole‐thioesters linked with an (Z)‐olefin. Selenols are also suitable for this strategy. Further derivatization of thioesters highlighted the potential utility of our method.
The 1,2,3-triazole-containing polycyclic architecture widely exists in a broad spectrum of synthetic bioactive molecules, and the development of expeditious methods to synthesize these skeletons remains a challenging task. In this work, the catalytic cyclization of biomass-derived 2-furylcarbinols with an azide to form fused triazoles is described. This approach takes advantage of a single catalyst Yb(OTf) 3 and operates via a furfuryl-cationinduced intramolecular [3 + 2] cycloaddition/furan ring-opening cascade.
Oxidation reactions have been extensively
studied in the context
of the transformations of biomass-derived furans. However, in contrast
to the vast literature on utilizing the stoichiometric oxidants, such
as m-CPBA and NBS, catalytic methods for the oxidative
furan-recyclizations remain scarcely investigated. Given this, we
report a means of manganese-catalyzed oxidations of furan with low
loading, achieving the Achmatowicz rearrangement in the presence of
hydrogen peroxide as an environmentally benign oxidant under mild
conditions with wide functional group compatibility.
A TiCl 4 -promoted cascade formal [3 + 2] cycloaddition/double ring-opening/chlorination of 2furylcyclobutanols with alkyl or aryl azides is described. This highly efficient transformation involves the formation/cleavage of several C−N, C−Cl, C−C, and C−O bonds in a single operation. It enables the quick construction of trisubstituted 1,2,3triazoles with an (E)-enone moiety and a 3-chloropropyl unit. The chlorinated products are readily transformed into other structurally diverse analogues.
A dearomative dimerization of furfuryl azides for the construction of furfuryl triazoles is developed. As a rare leaving group, azide is capable of initiating the generation of a furfuryl cation under the Lewis acid-catalyzed conditions, followed by reacting with the other azide to realize an intermolecular [3 + 2] cycloaddition/furan ring-opening cascade. By extending the reaction time, a fragmentation reaction of resulting furfuryl triazoles occurs to afford 1H-triazoles in high yield. Control studies demonstrated that key furfuryl cations also can be obtained from furfuryl triazoles. Furthermore, a chemoselective crosscycloaddition can be achieved between furfuryl azides and a benzyl azide.
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.