Arylnitroso Compounds

Tetrakis(alkyl isocyanide) complexes of nickel(O), Ni(CNR)4, and the mixed isocyanide complexes with phosphines and unsaturated molecules are strictly analogous to the corresponding carbonyl complexes.23,24 They are generally more stable than [Ni(CN)4]4-. Mixed isocyanide complexes have been prepared by the reaction of Ni(cod)2 and CNBu followed by reaction with the appropriate phosphine or unsaturated molecules (alkenes, arylnitroso compounds, azo compounds, etc.) as outlined in equations (7) and (S).25... 

Deoxygenation of 2-nitrosophenols with triphenylphosphine affords dihydro-phenazines, whereas similar deoxygenation of various metal complexes of 2-nitrosophenols yields phenazines or complexes of triphenyl(o-hydroxyphenylimino)phos-phoranes, depending on the metal. The reactions are believed to involve nitrene intermediates. It has been suggested that the assumed zwitterionic intermediate (92) in the arylphosphine-induced deoxygenation of arylnitroso-compounds arises by... 

Arylnitroso compounds of various types react with both electron-rich and electron-deficient dienes under mild conditions (usually 0-l(X)°C) to produce dihydrooxazines. As mentioned in the preceding section, Kresze s group has looked in considerable detail at orientational preferences and kinetics of [4 + 2] cycloadditions with various phenylnitroso compounds and substituted 1,3-dienes. Table 3-1 contains some of the results of cycloadditions of aromatic nitroso dienophiles with representative unsymmetrical 1- and 2-substituted dienes." Scheme 3-1 shows the subtle regiochemical trends that can be observed in a series of these reactions. These results were rationalized based on consideration of putative dipolar and nonpolar transition states and their relative stabilization by aromatic electron-donating and -withdrawing substituent groups. 

These nitroso compounds undergo [4 + 2] cycloadditions readily with 2,3-dimethylbutadiene to yield the expected adducts. This method was used to synthesize arylnitroso compound 11, which was in turn used to prepare a 3-pyrrolidinone via a Diels-Alder strategy (Scheme 3-V). The initial cycloaddition was apparently regioselective, giving only the isomer shown (cf. Scheme 3-III)."... 

A -Arylketenimine, 259 Arylmethylenemalondialdehyde, 180 2-Arylmethylene-l-tetralinthione, 217 Arylnitroso compound, 72-78 N-Arylpyrrole, 21-22, 73-74 A1-Aryls ulfiny limine. 259 Arylthienium salt, 233 4-Aryltriazolinedione, 159 N-Arylvinylketenimine, 259 Azabutadiene, 239-299... 

The regiochemistry of the addition of a-chloronitroso compounds with unsymmetrical acyclic dienes has been probed, and some results are listed in Table 3-II.lb 3a 23 In general, orientational preferences are in accord with those observed for arylnitroso compounds (cf. Table 3-1). As noted above, a glaring exception is the case of isoprene, which gives the opposite selectivities with chloronitroso compounds and nitrosobenzene. It was suggested that steric factors become important in cycloadditions... 

Cyclic intermediates of the type (231) have been ruled out in the reaction of aryl nitrones with arylnitroso-compounds. 

Ddlle, B., W. Tdpner and H.-G. Neumann. 1980. Reaction of arylnitroso compounds with mercaptans. Xenobiotica 10 527-536. 

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