Efficient One-Pot Synthesis of Mono- and Bis[di(2-pyridyl)phosphine Oxides] from Tris(2-pyridyl)phosphine

Abstract

The 1 H, 13 C and 31 P NMR spectra were recorded on a Bruker AV-400 spectrometer (400.13, 100.62 and 161.98 MHz, respectively) at 20-25 °C. 85% H 3 PO 4 /H 2 O was employed as external standard for 31 P NMR. IR-FT spectra were taken on a Bruker Vertex 70 spectrometer. The CHN microanalyses were performed on a Flash EA 1112 analyzer. Melting points (uncorrected) were determined using a Kofler micro hot stage. All reactions were carried out under dry argon atmosphere. Tris(2-pyridyl)phosphine was synthesized from red phosphorus and 2-bromopyridine in KOH/DMSO system, according to published procedure. 1 1-Chloromethylnaphthalene, 9-bromo-9H-fluorene and bis(chloromethyl)arenes were used as purchased (Aldrich). The remaining organic halides were distillated prior to use. The solvents used were purified by standard methods. The reactions were monitored by 31 P NMR following the disappearance of the signal of starting tris(2-pyridyl)phosphine (δ P = 0.08 ppm) and simultaneous appearance of a new signal, corresponding to a product. 2. X-Ray Diffractometry The data were collected on a Bruker D8 Venture diffractometer with MoK α radiation (λ = 0.71073) using the ϕ and ω scans.The structure of 3e was solved and refined by direct methods using the SHELX program set. 2 Data were corrected for absorption effects using the multi-scan method (SADABS). 3 Non-hydrogen atoms were refined anisotropically using SHELX. 2 CCDC 1477937 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif. Crystal data for 3e: C 17 H 15 N 2 OP (M =294.27 g/mol): triclinic, space group P-1 (no. 2), a = 8.3514(6) Å, b = 9.0996(7) Å, c = 10.2743(7) Å, α = 79.423(2)°, β = 80.739(2)°, γ = 81.985(3)°, V = 752.64(9) Å 3 , Z = 2, T = 100(2) K, μ(MoKα) = 0.182 mm-1 , Dcalc = 1.294 g/cm 3 , 40838 reflections measured (4.072 ≤ 2Θ ≤ 60.252°), 4419 unique (R int = 0.0587, R sigma = 0.0363) which were used in all calculations. The final R 1 was 0.0600 [I > 2σ(I)] and wR 2 was 0.1853 (all data).