NUCLEOPHILIC SUBSTITUTION REACTIONS OF TETRABUTYLAMMONIUM ACI-NITRONATES WITH P-SUBSTITUTED NITROBENZENES

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 β-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.