Aleksandr A. Yurchenko

N-Phosphorylated Imidazolium Salts as Precursors to 2- and 5-Phosphorylated Imidazoles and New Imidazol-2-ylidenes Featuring the PNCN Unit

It has been experimentally proven that the reaction of 1- or 1,2-disubstituted imidazoles with diorganylphosphorus(III) halides proceeds via initial formation of N-phosporylated imidazolium salts. Treatment of these salts with strong bases results in phosphorylation of the parent imidazoles at the 2- or 5-positions, correspondingly. In a previous case, imidazol-2-ylidenes are formed as intermediates. With both N1 and N3 atoms bearing sterically demanding or/and π-donating groups, deprotonation of 1,3-disubstituted imidazolium salts with NaN(SiMe(3))(2) afforded new stable N-phosphorus-substituted Arduengo-type carbenes.

Tungsten pentacarbonyl as a potential protecting group for soft lewis base centres in alkylation of multifunctional molecules

Abstract Reaction of W(CO) 6 or (PhNH 2 )W(CO) 5 with the molecules which possess both diphenylphosphanyl- and dialkylamino group or nitrogen — containing hetcrocyclic ring proceeds selectively through “soft” Lewis base groups and can be used for the protection of the groups from alkylalion. As a rule, the diphenylphosphanyl group participates in the co-ordination, but in some cases an sp 2 -hybridized nitrogen was shown to be the preferable co-ordination site. The new synthesized compounds have been characterized by NMR, IR spcctroscopy, and elemental analysis.

C-acylation of electron-rich heterocyclic compounds with Kirsanov isocyanate

Pyrroles, indoles, indolizines, and 2-methylfuran are vigorously C-acylated with isocyanatophosphoryl dichloride. The resulting heteroaryl-substituted isocyanatophosphoryl dichlorides provide a convenient access to a variety of products.© 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 343–348, 1999

1,2‐migration in N‐phosphano functionalized N‐heterocyclic carbenes

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.

Synthesis and Structure of Phosphanylated Bis-Triazoles as Potential Ligands for Chiral Catalysts

Potential atropisomeric ligands, diphenylphosphane derivatives of bis-triazoles, were synthesized by direct phosphanylation of the starting bis-triazoles with chlorodiphenylphosphane. Their crystal structure was elucidated by X-ray diffractional analysis. The conformations of these compounds were modeled by DFT calculations.