75848-83-8Relevant articles and documents
C-Nitrosoformamides, a New Class of Transient Dienophiles Formed by Oxidation of N-Hydroxyureas
Christie, Clifford C.,Kirby, Gordon W.,McGuigan, Henry,Mackinnon, John W. M.
, p. 2469 - 2474 (2007/10/02)
Oxidation of hydroxyurea with sodium or tetraethylammonium periodate in the presence of cyclopentadiene gave a cycloadduct (3a) formed, apparently, by capture of the transient dienophile, C-nitrosoformamide.N-Methyl-, N-phenyl-, N,N-dimethyl-, and N,N-diphenyl-C-nitrosoformamide were likewise trapped as their cycloadducts with cyclopentadiene.Cycloadducts of 2,3-dimethylbuta-1,3-diene, thebaine, ergosteryl acetate, and 9,10-dimethylanthracene (DMA) were prepared similarly.The cyclopentadiene adducts (3) dissociated at 80 deg C in the presence of 2,3-dimethylbuta-1,3-diene to give the corresponding adducts (4) of the nitrosoformamides and dimethylbutadiene.Unexpectedly, the 1,4-adducts (4) were accompanied by substantial amounts of hydroxamic acids (5) arising from 'ene' reactions of the nitrosoformamides and dimethylbutadiene.The cyclopentadiene adducts of N,N-dimethyl- and N,N-diphenyl-C-nitrosoformamide, when heated alone, decomposed to give the corresponding carbamic anhydrides.The cycloadduct (15) of DMA and C-nitrosoformamide dissociated at 40 deg C in the presence of thebaine (11) to give the thebaine adduct (12; R=H) and DMA.
