(1,1'-Biphenyl)-2,2'-diol → Dibenzo(d,f)(1,3,2)dioxaphosphepin, 6-chloro-

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Reaction Steps

A solution of 2,2′-biphenol (28.1 g, 0.151 mol) in 49 mL phosphorus trichloride was heated at reflux for 2 hours. The excess PCl3 was removed by distillation. The residue was purified by vacuum distillation (140-143° C. at 0.5 mm Hg) to give 30.70 g (81% yield) 1,1′-biphenyl-2,2′-diyl phosphorochloridite (as a clear viscous oil which solidified to a white solid upon standing at room temperature in an inert atmosphere for an extended period of time). 31P{1H}NMR (121.4 MHz, d8-toluene): δ 180.1 (s), 85% H3PO4 external reference. To a solution containing 1.018 g (2.84 mmoles) of 2,2′-dihydroxy-3,3′-di-t-butyl-5,5′-dimethoxy-1,1′-biphenyl and 0.575 g (5.68 mmoles) of NEt3 in 15 ml of tetrahydrofuran (THF) was added 1.412 g (5.68 mmoles) of 1,1′-biphenyl-2,2′-diyl phosphorochloridite in 5 ml of THF. The mixture was stirred overnight at room temperature. The mixture was filtered through celite, washed with THF and solvent removed to give 2.2 g of white solid. 31P{1H} nmr (121.4 MHz, C6D6): 145.15 s and 138.5 s. 1H nmr (300 MHz, C6D6): singlet at 3.15 and 1.3 along with aromatic resonances.

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