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In this study, the first highly chemoselective amidation of Boc and amide groups of N -R- N -Boc arylamides is advanced. This practical and operationally-simple method enables the preparation of either N -aroylureas or imides in good to excellent yields without addition of transition metals. The choice of base plays a significant role in controlling the reactivity of the inequivalent carbonyl groups. The amidation of the Boc group was observed with arylamides, ArCONH 2 , when subjected to KO t Bu while imides were produced with LiOH. DFT studies are employed to explore the divergent mechanisms. It is anticipated that these chemoselective methods will be of interest to the synthetic and medicinal chemistry communities. 

Abstract The use of nitroarenes as amino sources in synthesis is challenging. Herein is reported an unusual, straightforward, and transition metal-free method for the net [3 + 2]-cycloaddition reaction of 2-azaallyl anions with nitroarenes. The products of this reaction are diverse 2,5-dihydro-1,2,4-oxadiazoles (>40 examples, up to 95% yield). This method does not require an external reductant to reduce nitroarenes, nor does it employ nitrosoarenes, which are often used in N–O cycloadditions. Instead, it is proposed that the 2-azaallyl anions, which behave as super electron donors (SEDs), deliver an electron to the nitroarene to generate a nitroarene radical anion. A downstream 2-azaallyl radical coupling with a newly formed nitrosoarene is followed by ring closure to afford the observed products. This proposed reaction pathway is supported by computational studies and experimental evidence. Overall, this method uses readily available materials, is green, and exhibits a broad scope.