Halo-denitrations

Reaction of aryl organometallic compounds with halogens Aryl halide exchange halo-denitration halo-dehydroxylation Reaction between diazonium salts and iodide ion Heating of diazonium fluoroborates (Schiemann)... 

Activated nitro and halo substituents have been efficiently replaced by a variety of alkyl groups via SsAx reaction with carbanions. Examples include the displacement of the nitro group in compounds (10 X = 4-PhCO, 4-MeOCO, 4-CN, 4-N02, 4-PhS02, 3,5-(CF3>2) by the anion of 2-nitropropane in HMPA at room temperature (equation 2),83 and the reaction of p-dinitrobenzene with several ketones, esters and nitriles (RH equation 3) in Bu OK/liquid NH3 at -70 C.84 Interestingly, under the latter reaction conditions, p-chloronitrobenzene gave the product of alkylation rather than of SNAr displacement of chloride, as in equation (4).85 Further examples include the dehalogenation of p-halonitrobenzenes by 9-fluorenyl anions in DMSO at room temperature,34 and dehalogenation and denitration reactions by the carbanions of phenyl- and diphenyl-acetonitrile in DMSO or under PTC conditions.86... 

Tanikaga and coworkers have reported the addition of nitroalkane anions to a-halo-a,P-unsaturated sulfoxides [72]. Further development of this work led to the use of nitroalkanes as alkyl group equivalents in conjugate addition to a,P-unsaturated sulfoxides [73-75]. Primary or secondary nitroalkanes such as 2-nitropropane (77), with DBU as a non-nucleophilic base, add to a,P-unsaturated sulfoxides including phenyl vinyl sulfoxide (26) to give products such as (78), which can be denitrated to yield (79) (Scheme 5.25). The Michael addition of nitroalkanes, and of diethyl N-acetylaminomalonate, to racemic phenyl vinyl sulfoxide using solid-liquid phase-transfer catalysis in the absence of solvent has also been accomplished [76]. 

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