Nucleophilic addition and displacement in the reaction of 2,4,6-trimethylphenoxide ion with 1,3,5-trinitrobenzene. An oxygen-bonded aryloxide σ-complex

Reaction of 1,3,5-trinitrobenzene with potassium 2,4,6-trimethylphenoxide in dimethyl sulfoxide solution leads to σ-complex formation concurrently with displacement of a nitro group. The results provide definitive evidence for σ-complex formation via the oxygen of aryloxide ion in this system, and contrast with the situation that obtains with phenoxide ion itself, which under corresponding conditions yields the carbon-bonded σ-complex as the product of thermodynamic control. Stereoelectronic factors in σ -complex formation and in the diaryl ether resulting from nitro displacement are also discussed.