title: 1,2-migration in N-phosphano functionalized N-heterocyclic carbenes.
abstract: 1,2-Migration of the phosphano-group to the carbene center in N-phosphano functionalized N-heterocyclic carbenes has been studied by density functional theory (DFT) calculations. An intramolecular mechanism with a three-center transition state structure seems to be most plausible for the isolated carbenes, while an intermolecular pathway catalyzed by azolium salts may be preferable for a migration proceeding in the course of generating the carbenes in situ. Our calculations show that amino-substitution at the phosphorus atom and an enhanced nucleophilicity of the heterocycle scaffold facilitate the phosphorus shift. Calculated singlet-triplet energy gaps do not correlate with thermodynamic stability of the studied carbenes and their disposition toward the 1,2-rearrangement.
authors.affiliation: Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Murmans'ka str. 5, Kyiv, 02660, Ukraine.
authors.forename: Andrey A
authors.initials: AA
authors.lastname: Kirilchuk
authors.forename: Aleksandr A
authors.initials: AA
authors.lastname: Yurchenko
authors.forename: Aleksandr N
authors.initials: AN
authors.lastname: Kostyuk
authors.forename: Alexander B
authors.initials: AB
authors.lastname: Rozhenko
keywords: DFT; carbenes; intramolecular migration; phosphanylated heterocycles