Reactions of transient C-nitrosocarbonyl compounds with dienes, mono-olefins, and nucleophiles

Abstract

Nitrosocarbonylbenzene and nitrosocarbonylmethane, formed as transient intermediates by oxidation of benzo- and aceto-hydroxamic acid, respectively, with tetraethylammonium periodate, are trapped by cyclopentadiene to give the corresponding cycloadducts (5). The adduct (5; R = Ph) dissociates in solution at 80 °C to reform nitrosocarbonylbenzene, which reacts with thebaine (1) to give (4; R = Ph) and with triphenylphosphine to give phenyl isocyanate. Cycloadducts of nitrosocarbonylbenzene with cyclohexa-1,3-diene (6) and with cycle-octatetraene (7) have also been prepared. The adduct (3; R = Ph) of nitrosocarbonylbenzene and 9,10-dimethylanthracene, when heated with 1-allyl-3,4-methylenedioxybenzene, oct-1-ene, or 2,5-dimethylhexa-2,4-diene, gives the corresponding [ene] reaction products of the olefins and nitrosocarbonylbenzene. When heated alone, the adduct (3; R = Ph) gives 9,10-dimethylanthracene, benzoic anhydride, and nitrous oxide. Oxidation of 2,4,6-trimethylbenzohydroxamic acid in the presence of thebaine gives the adduct (4; R = 2,4,6-trimethylphenyl). However, 2,4,6-trimethylnitrosocarbonylbenzene is insufficiently stable to be isolated; in the absence of a diene it decomposes to give 2,4,6-trimethylbenzoic anhydride as the major product.