Palladium‐Catalyzed Regioselective Dehydrogenative C–H/C–H Cross‐Coupling of Pyrroles and Pyridine
<i>N</i>
‐Oxides
作者:Shanshan Liu、C. Christoph Tzschucke
DOI:10.1002/ejoc.201600680
日期:2016.7
The palladium-catalyzed cross-dehydrogenative coupling of N-alkylpyrroles and pyridine N-oxides gave the corresponding pyrrolylpyridine N-oxides. Cu(OAc)2·H2O as a co-catalyst with air as the terminal oxidant led to preferential coupling in the β-position, whereas AgOAc as the stoichiometric oxidant resulted in preferential coupling in the α-position. N-(Benzyloxymethyl)pyrrole derivatives were deprotected
Formation of the 5-Azoniafulvene Ion and its Benzo-annellated Analogue from N-<i>Mannich</i>Bases of Pyrrole and Indole
作者:Ulrich Burger、Alain O. Bringhen、Philippe J. Wirthner、Jean-Claude Schärer
DOI:10.1002/hlca.19850680822
日期:1985.12.18
N-atom rather than at the pyrrole ring. Spontaneous cleavage of the resulting quaternary acylammonium salts affords the 5-azoniafulvene ion (3). This higly reactive iminium ion, and its benzo-annellated analogue (4) can be trapped by electron rich aromatic compounds such as N-methylpyrrole or N,N-dimethylaniline. More elaborate N-Mannich bases are accessible by addition of indoles to enamines.
intercepted by aldehydes and converted to the title alkenes in a few straightforward steps. Protonation of 1,1-di(1-pyrrolyl)ethylene (10) is found to occur under kinetic control at the terminal olefinic position. In HBF4. Me2O the resulting 5-azionafulvene-type ion 14 can be observed by low-temperature NMR spectroscopy. In FSO3H, however, protonation is directed under thermodynamic control to both pyrrole
fumarate (5), prepared by condensation of 1-hydroxypyrrole (1a) with trans-3-(methoxycarbonyl)-acryloyl chloride (4), undergoes a facile interamolecular Diels–Alder reaction to give the product (6), the first intramolecular cycloaddition of a pyrrole.
Utility of13C NMR spectroscopy in monitoring the course of a complex reaction sequence: Reaction of pyrrole with formaldehyde
作者:Alan R. Katritzky、Kam Wah Law
DOI:10.1002/mrc.1260260208
日期:1988.2
The complex course of the reaction of pyrrole with formaldehyde has been completely elucidated by quantitative 13C NMR spectroscopy using the inverse-gated decoupling technique. The final product is 2,5-bis(hydroxymethyl)pyrrole (with a free 1-position), but three main intermediates containing 1-hydroxymethyl groups were identified, and the rise and subsequent fall of their populations followed. The intermediacy of additional compounds (formals) also renders the reaction more complex. The molar fractions of four hydroxy-methylpyrroles present in the reaction mixtures were calculated from the 13C NMR data and plotted against time. At 45 and 65°C pyrrole reacted completely with formaldehyde in 1 h and in less than 30 min, respectively. This work illustrates the utility of the 13C NMR investigation of an industrially important reaction.