Allylic nitro compounds elimination

Recently, elegant synthesis of ruin -MRS carbapenum has been reported. Sequential reaction of nitromethane via conjugate addition-elimination to a,fi-unsanirated esters followed by Pd-catalyzed subsdnidon of the residdng allyl nitro compound with the naphthosultam affords the allyladon product which is an and fEq. 7.20. ... 

A new synthesis of substituted 1,3-dienes by reductive elimination of allylic nitro derivatives has been reported (Eq. 7.134).180 Tertiary allylic nitro compounds, bearing an acetate group in the (3-position, smoothly undergo reductive elimination to give conjugated 1,3-dienes when treated with chromous acetate and 2,2-dipyridine in DMF at 111-120 °C. 

DeShong (Scheme 20). Thus, reaction of nitrones with vinyl silanes followed by reduction provides Peterson - type intermediates which can then be eliminated to either Z- or E-products. Homoallylic amines were also prepared using allylsilane in the initial cycloaddition. Substitution reactions of allylic nitro compounds have received considerable attention and some examples are outlined in Scheme 21. In each case, examination of the regiochemistry of the reaction was of paramount concern, the results using palladium being superior to the SnCl mediated process. Allylic sulphides constitute yet another group of... 

Conjugate addition-elimination reaction of nitromethane with p-trifloxy acrylate in the presence of TMG (3) was reported by Chung et al. [11]. Treatment of enol triflate 46 with nitromethane and DMPU as a co-solvent in the presence of TMG (3) gave allyl nitro compound 47 in 60-70% yield via a conjugate addition-ehmination process. In this... 

Similarly, ethyl nitroacetate afforded, with 1,4-naphto-quinones, fair yields of condensed isoxazoline derivatives as a result of dehydration followed by elimination or dehydrogenation [80]. Later, more examples of condensations of ethyl nitroacetate and alkenes in the same reaction conditions have been reported to compete with oxidation [81]. The intramolecular version, using allyl nitroacetate 16 in the presence of Cu(II) and Mn(III), gives mainly the bicyclic isoxazoline 17 as the condensation product, predominant over monoelectronic oxidation 18 (Scheme 8.6). Noticeably, the intramolecular cyclization occurs with Cu (II) or Co(II) instead of Mn(III) acetate. As expected, secondary nitro compounds undergo only radical reactions. Condensations are reported to occur via intermediate nitrile... 

Ono and coworkers have extended the radical elimination of v/c-dinitro compounds to P-nitro sulfones151 and P-nitro sulfides.138,152 As P-nitro sulfides are readily prepared by the Michael addition of thiols to nitroalkenes, radical elimination of P-nitrosulfides provides a useful method for olefin synthesis. For example, cyclohexanone is converted into allyl alcohol by the reaction shown in Eq. 7.110. Treatment of cyclohexanone with a mixture of nitromethane, PhSH, 35%-HCHO, TMG (0.1 equiv) in acetonitrile gives ahydroxymethylated-P-nitro sulfide in 68% yield, which is converted into the corresponding allyl alcohol in 86% yield by the reaction with Bu3SnH.138 Nitro-aldol and the Michael addition reactions take place sequentially to give the required P-nitro sulfides in one pot. 

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