Investigating N-methoxy-N′-aryl ureas in oxidative C–H olefination reactions: an unexpected oxidation behaviour
作者:Jens Willwacher、Souvik Rakshit、Frank Glorius
DOI:10.1039/c1ob05636k
日期:——
Herein, we report a urea derived directing group for mild and highly selective oxidative CâH bond olefination. Subsequent intramolecular Michael addition affords dihydroquinazolinones in good yields. The NâO bond of the urea substrate exhibits superior oxidative behaviour compared to a variety of other external oxidants.
NN′-dihydroxyurea or NN′-dimethoxyurea. Dihydroxyurea forms a tetrabenzoyl derivative which gives O-benzoyl benzhydroxamate in hot aqueous ethanol. With phenyl isocyanate, dihydroxyurea gave hydroxydiphenylbiuret; with xanthydrol, xanthone and hydroxyurea were produced. Hydroxyurea and dihydroxyurea were determined colorimetrically with amminoprusside. In alkali, dihydroxyurea formed cyanate and hydroxyurea;
Oxidative (3+3) Cycloaddition/Ring-Opening Reactions of Simple Urea Derivatives and <i>N</i>,<i>N</i>′-Cyclic Azomethine Imines to Construct 1,2,3,5-Tetrazine-4(1<i>H</i>)-one Derivatives
作者:Zhao-Lin He、Wen Tian、Gang Wang
DOI:10.1021/acs.joc.3c00525
日期:2023.7.7
A novel oxidative (3 + 3) cycloaddition/ring-opening reaction of N,N′-cyclic azomethineimines with the in situ generated diaza-oxylallyl cations from simple urea derivatives in the presence of base and PhI(OAc)2 has been developed. This transformation performs well over a broad substrate scope, which provides facile and rapid access to 1,2,3,5-tetrazine-4(1H)-one derivatives in good yields.