Phosphorus mediated imidazolinium to oxazolium ring rearrangement

Abstract

An unexpected rearrangement occured when an imidazolinium based OCO pincer-type ligand (1) was reacted with PCl3 producing a chlorophosphine with a pendant oxazolium "arm" (3). The mechanism of this rearrangement...

Intramolecular C–N bond activation by a geometrically constrained PIII-centre

“…However, when a catalytic amount of HCl was added to 9 and the reaction mixture was heated to 50 1C, full conversion to 5 was achieved after 48 h (Scheme 4, path c). Notably, the formation of CO in this transformation was confirmed by its observation in the 13 C NMR spectrum at d = 184 ppm (see Fig S42 , ESI †). 16 Although stepwise experiments partially solved the puzzle of formation of 4 and 5, the most crucial and interesting last step of the two reactions, i.e., transformation of 7 to 4 and transformation of 9 to 5, in the presence of HCl remained unclear.…”

“…We recently reported a phosphorous mediated rearrangement of an OCO type ligand, 13 bis-phenol dihydroimidazolinium ( 1 ), to compound 2 while trying to prepare the geometrically constrained P III cation ( 3 ) by double deprotonation of 1 and its further reaction with PCl 3 (Scheme 1a). 14 Due to this failure, we decided to fully deprotonate 1 to 1-Li 2 C : and then react it with PCl 3 ; this however as well did not yield the desired 3 (Scheme 1b).…”

Reversible Oxidative Addition of Nonactivated C–H Bonds to Structurally Constrained Phosphenium Ions

“…Enhanced biphilic reactivity arises from altering the local symmetry at phosphorus enforced by tethered ligand systems, which in turn decreases the HOMO–LUMO gap. While previously restricted to polar E–H bonds (E = O, S, N), a single-center OA of dihydrogen to phosphorus was recently reported employing a rigid, carborate-based ligand framework . Fewer examples for inserting P(III) compounds into C–H bonds exist, but were demonstrated with electrophilic, two-coordinate phosphenium ions .…”