Reversal Reactivity of β-Alkylnitroalkenes as 1,3-Binucleophiles: Application to Nitroarenes

What is it about?

An efficient pyrrolidine : 4-ClBzOH salt (catalyst IV) catalyzed [3+3] cyclization reaction of β-alkyl-substituted nitroalkenes as 1,3-binucleophiles with various β-aryl/alkyl/alkenyl-substituted acroleins in an open-atmosphere is reported. Eventually, this tunable organocatalytic reaction creates one C−C and C=C bonds selectively that turns out to have a wide substrate scope, which affords a series of substituted nitroarenes in good to high yields. In addition, several other positive features are associated with this organocatalytic approach such as evading toxic metal-catalysts, no need for external oxidant and nitrating agent, 100% carbon-economical, excellent tolerance of functionalities, water as a sole by-product, circumventing of pre-functionalized arenes etc. Moreover, a range of important hetero-and carbocycles such as 2-arylcarbazole, 2,6-diphenylindole, 2′-chloro-1,1′ : 4′,1′′-terphenyl and 1 : 1′ : 4′,1′′-terphenyl were accessed from nitroarenes through our unique methods.

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Why is it important?

An efficient pyrrolidine/4-ClBzOH salt-catalyzed [3+3] cyclization of β-alkyl-substituted nitroalkenes and β-aryl/alkyl/alkenyl-substituted acroleins is reported. This oxidant-metal-free route delivers nitroarenes in satisfactory yields. Furthermore, few useful molecules such as 2-phenylcarbazole, 2,6-diphenylindole, 2′-chloro-1,1′ : 4′,1′′-terphenyl, 1 : 1′ : 4′,1′′-terphenyl etc could synthesize from nitroarenes by simple synthetic operations.