Reversal Reactivity of β‐Alkylnitroalkenes as 1,3‐Binucleophiles: Application to Nitroarenes using Organocatalysis

Abstract

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 CÀ 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 metalcatalysts, no need for external oxidant and nitrating agent, 100% carbon-economical, excellent tolerance of functionalities, water as a sole by-product, circumventing of prefunctionalized 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.

DBU- and DABCO-Promoted Selective Access to 2,5-Diarylnitrobenzoates and Cyclohexenones via One-Pot Reactions

“…We recently explored the 1,3-binucleophilic nature of 3-nitroallylarenes in the domino reaction with -aryl-substituted acroleins catalyzed by pyrrolidine acid salt as a LUMO lowering catalyst to generate substituted nitroarenes (Scheme 1c). 18 Inspired by our previous findings, we speculate that base may favor the deportation of a -proton of nitroalkene to generate a carbanion species which would smoothly join in the cyclization reaction with ,-unsaturated -ketocarbonyl as an antecedent to nucleophilic acceptor, targeting the possibility of nitrobenzoate derivative.…”

Organocatalyzed diastereoselective cyclization of β-alkyl nitroolefins with alkylidene malononitriles: new approach to azetidine nitrones and isoxazoles

“…11 Therefore, the search for an alternate mild, metal-free, one-pot route for rapidly delivering substituted azetidine nitrones with embedded stereocenters using simple substances remains a formidable research target for chemists. Based on our recent successful organocatalyzed cyclization reactions between β-alkyl nitroalkenes and β,γ-unsaturated α-ketoesters 12 /β-substituted acroleins, 13 we envisaged that base-assisted cyclization of β-alkyl nitroalkene with a powerful Michael acceptor such as alkylidene malononitrile may take place in a similar fashion. Subsequently, this combination would allow access to a new class of cyclic products.…”