[alpha]-nitrosulfones: synthetic and mechanistic studies

James K. Murray Jr.

doi:10.17918/etd-101

Three-[alpha]-substituted nitroethylene derivatives were prepared in situ from phenylsulfonylnitromethane, [alpha]-nitroacetophenone, and ethyl nitroacetate and allowed to react with a series of dienes to yield the corresponding Diels-Alder cycloadducts. The same nitroethylene derivatives were also prepared from the corresponding [beta]-sulfoxides via elimination. The [beta]-sulfoxides were prepared from the corresponding [beta]-sulfides which were in turn prepared by trapping the nitroethylene derivatives with thiophenol. The nitroethylene derivatives were found to exhibit both dienophile and heterodiene behavior in the cycloaddition reactions that were examined. Their behavior as heterodienes afforded nitronic esters which were observed to undergo [3,3]-sigmatropic rearrangement. Rearrangement afforded the same bicyclic nitro compounds obtained via direct cycloaddition. The sulfone group in the nitrosulfone cycloadducts could be replaced by the anion of 2-nitropropane in a SRN1 process. Treatment of the dianion of phenylsulfonylnitromethane with unbranched aldehydes led to formation of [beta],[gamma]-unsaturated [alpha]-nitrosulfones as the isolable products. Under buffered conditions, the [beta],[gamma]-unsaturated [alpha]-nitrosulfones could be tautomerized to conjugated [alpha],[beta]-unsaturated [alpha]-nitrosulfones and these could be trapped with phenylsulfonylnitromethane to yield the corresponding Michael adducts. If a thiol was initially present, [alpha],[beta]-unsaturated [alpha]-nitrosulfones could be intercepted to give the corresponding [beta]-sulfides with little or no formation of [beta],[gamma]-unsaturated [alpha]-nitrosulfones. The [beta]-sulfides were obtained as a mixture of diastereomers which upon silica gel chromatography converted to a single crystalline diastereomer. The diastereomers of bis(1,3-phenylsulfonyl)-1,3-dinitropropane underwent isomerization. The elimination of nitrous acid from unsaturated [alpha]-nitrosulfones was observed affording dienes. Synthesis of 6-nitro-6-phenylsulfonylhexanenitrile was accomplished in preparation for reduction and cyclization.

[alpha]-nitrosulfones: synthetic and mechanistic studies

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[alpha]-nitrosulfones: synthetic and mechanistic studies

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