π-Delocalization in phosphaphthalimide and its ambident reactivity (O/P) toward main-group electrophiles

Abstract

The report on phosphaphthalimide (1), the phosphorus analogue of the phthalimide anion, dates back to forty years ago. However, the presence of π-delocalization between two-coordinated phosphorus centre and neighbouring carbonyl...

Cyclo‐Bis(Acyl)phosphine Oxides as Efficient Photoinitiators for Radical Polymerization

“…Notably, the endocyclic P−C bonds (1.861–1.882 Å) are significantly longer than these of exocyclic counterparts P−C bonds (1.814–1.829 Å) in compounds 4 a , 4 b , 4 d , and 4 f , respectively. This phenomenon can be attributed to the favorable hyperconjugation of n(O1)→σ*(P2‐C1) interaction in acylphosphine [31,34] . In 4 c , however, the endocyclic P−C bonds (1.8734 Å) are only elongated slightly than that of the exocyclic P−C bond (1.8694 Å) due to the steric bulk of triphenylmethyl group.…”

“…We recently reported the largescale synthesis of sodium phosphaphthalimide 1 , achieving an isolated yield of 78 % with a production exceeding 40 g. Subsequently functionalization of 1 at the phosphorus atom was carried out with carbon‐based electrophiles [31] . Likewise, monitoring the reaction between 1 and benzyl halides 2 a – 2 f in tetrahydrofuran at room temperature revealed the exclusive formation of 3 a – 3 f as the products, accompanied with the appearance of a new singlet at δ=−22.0, −7.7, 8.6, −20.6, −24.0, and −20.8 ppm in the proton‐decoupled 31 P NMR spectra, respectively.…”

“…This phenomenon can be attributed to the favorable hyperconjugation of n(O1)!σ*(P2-C1) interaction in acylphosphine. [31,34] In 4 c, however, the endocyclic PÀ C bonds (1.8734 Å) are only elongated slightly than that of the exocyclic PÀ C bond (1.8694 Å) due to the steric bulk of triphenylmethyl group. Remarkably, all endocyclic PÀ C bonds in 4 a-4 f are markedly shorter than the corresponding distance between phosphorus atom and acyl carbon (av.…”

“…All synthesis procedures were conducted under an inert atmosphere of dry nitrogen, using standard Schlenk techniques, Dry, oxygen-free solvents were employed unless otherwise specified. 1 H NMR, 31 P NMR and 13 C NMR data were measured on Bruker Avance 400 or 300 MHz spectrometers at 25 °C. X-ray single crystal diffraction Measured by XtaLAB PRO.…”

“…The obtained solid was dried in vacuo affording a yellow powder of 3 a (2.05 g, 8.07 mmol, Yield: 69 %). 31 To the THF solution (20 mL) of 3 a (508 mg, 2 mmol), a THF solution (10 ml) of mCPBA (max 85 %, 577 mg) was added dropwise. The color of the solution turned to dark yellow within a few seconds.…”