(R,R)-Et-DuPHOS Monoxide

Abstract

[924294-55-3] C22H36OP2 (MW 378.47) InChI = 1S/C22H36OP2/c1-5-17-13-14-18(6-2)24(17)21-11-9-10-12-22(21)25(23)19(7-3)15-16-20(25)8-4/h9-12,17-20H,5-8,13-16H2,1-4H3/t17-,18-,19-,20-/m1/s1 InChIKey = PFNSFIIPVBDTTF-UAFMIMERSA-N (chiral hemilabile ligand for transition metals; copper complexes exhibit high enantioselectivity and reactivity in a variety of organic reactions) Alternative Names: (R,R)-Et-DuPHOS(O); (R,R)-Et-BozPHOS; 1,2-bis[(2R,5R)-2,5-diethylphospholano]benzene monoxide; (2R,5R)-1-{2-[(2R,5R)-2,5-diethylphospholan-1-yl]phenyl}-2,5-diethylphospholane 1-oxide. Physical Data: −148 ° (c = 7.9, benzene).1 Solubility: soluble in most organic solvents (such as diethyl ether, THF, CH2Cl2, etc.); insoluble in water. Form Supplied in: white solid; commercially available in both enantiomers. Analysis of Reagent Purity: 1H (400 MHz, C6D6) δ 7.75–7.71 (m, 1H), 7.64–7.61 (m, 1H), 7.29–7.20 (m, 2H), 2.53–2.42 (m, 3H), 2.20–2.03 (m, 7H), 1.97–1.95 (m, 2H), 1.83–1.70 (m, 4H), 1.44–1.38 (m, 4H), 1.06 (dt, J = 11.4, 7.3 Hz, 6H), 0.98–0.84 (m, 6H). 31P NMR (162 MHz, C6D6) 60.6 (d, J = 3.7 Hz), 2.5. Handling, Storage, and Precautions: as a solid, Et-DuPHOS monoxide is substantially air stable, but bottles should be flushed with N2 or Ar and kept tightly closed for prolonged storage. In solution, Et-DuPHOS monoxide is slowly air oxidized to the corresponding dioxide. Preparative Method: Et-DuPHOS monoxide is prepared in a three-step sequence from commercially available Et-DuPHOS: (1) phosphine monoprotection with borane; (2) oxidation with hydrogen peroxide; (3) phosphine deprotection with DABCO™ (eq 1).2 (1) Purification: typically used as obtained from commercial sources. Impurities such as Et-DuPHOS and Et-DuPHOS dioxide can be removed by flash chromatography using 5% methanol in ethyl acetate as eluent.