A metal-free nitration of the C(sp 3 )ÀH bonds of 2-oxindoles with t-BuONO through radical coupling reaction at room temperature has been developed. Using t-BuONO both as a nitrating reagent and as an oxidant, to couple with the C(sp 3 )ÀH bonds of 2-oxindoles, thus forming a new CÀN bond without using any other reagents. This reaction provides a green and straightforward approach to some useful 3-nitro-2-oxindoles in moderate to good yields.

A novel metal-free C­(sp 3)–H amination of 2-oxindoles with alkylamines to afford C–N coupling products under mild conditions has been exploited. A series of 3-substituted 2-oxindoles and primary/secondary amines substrates were found to be well tolerated, affording the corresponding 3-substituted 3-aminooxindoles in 43%–92% yields. This method uses the economical and environmentally friendly “I2–TBHP” system, and the mechanistic studies revealed that the procedure undergoes through a radical pathway.

A new pattern for nitrative cyclization of 1,6-enynes with t-BuONO has been reported for the synthesis of various 2pyrrolidinone derivatives in 45−88% yields. This novel method is operationally simple and proceeds under very mild conditions without using any additives. The reaction pathway involves nitro radical addition toward an alkenyl group/5-exo-cyclization/Habstraction sequence, allowing a highly regioselective and practical protocol toward the formation of new C−N and C−C bonds.

A facile and scalable two-step method (including pyrolysis and magnetron sputtering) is created to prepare a core‒shell structured composite consisting of cotton-derived carbon fibers (CDCFs) and nano-copper. Excellent hydrophobicity (water contact angle = 144°) and outstanding antibacterial activity against Escherichia coli and Staphylococcus aureus (antibacterial ratios of >92%) are achieved for the composite owing to the composition transformation from cellulose to carbon and nano-size effects as well as strong oxidizing ability of oxygen reactive radicals from interactions of nano-Cu with sulfhydryl groups of enzymes. Moreover, the core‒shell material with high electrical conductivity induces the interfacial polarization loss and conduction loss, contributing to a high electromagnetic interference (EMI) shielding effectiveness of 29.3 dB. Consequently, this flexible and multi-purpose hybrid of nano-copper/CDCFs may be useful for numerous applications like self-cleaning wall cladding, EMI shielding layer and antibacterial products.

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