Nucleophilic Substitution Reactions of Tetrabutylammonium <i>aci</i> -Nitronates with p-Substituted Nitrobenzenes

Abstract

The reactions of tetrabutylammonium aci -nitronates with p -dinitrobenzene in dimethyl sulfoxide, benzene or acetone proceed far more rapidly than the reactions of the corresponding lithium salts and give, in unhindered cases, good yields of C-arylates, e.g. p -(1-methyl-1-nitroethyl)nitrobenzene (in 73-89% yields) and p -nitro(l,3,3-trimethyl-1-nitrobuty1)benene (in 70% yield). With more sterically hindered nitronates, O -arylation increases, giving phenols and ketoxime O - p -nitrophenyl ethers, presumably derived from the novel, intermediate p -nitrophenyl aci -nitronate esters. aci -Nitronate ions with more than two ß-methyl groups gave no C -arylation. Similar results were obtained with p -fluoronitrobenzene and p -nitrobenzonitrile, A mechanism for the conversion of the intermediate aci -nitronate esters into the ketoxime ethers is proposed.