Reaction SMILES: [CH3:1][C:2]1([CH3:33])[CH2:8][C:7](=[O:9])[CH2:6][CH2:5][C:4]([CH3:11])([CH3:10])[P:3]1[C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][C:13]=1[C:18]1[C:23]([CH:24]([CH3:26])[CH3:25])=[CH:22][C:21]([CH:27]([CH3:29])[CH3:28])=[CH:20][C:19]=1[CH:30]([CH3:32])[CH3:31].B(F)(F)F.[CH3:38]COCC.C[Si](C=[N+]=[N-])(C)C>Cl>[CH3:33][C:2]1([CH3:1])[CH2:8][C:7](=[O:9])[CH2:38][CH2:6][CH2:5][C:4]([CH3:11])([CH3:10])[P:3]1[C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][C:13]=1[C:18]1[C:23]([CH:24]([CH3:25])[CH3:26])=[CH:22][C:21]([CH:27]([CH3:29])[CH3:28])=[CH:20][C:19]=1[CH:30]([CH3:31])[CH3:32]
Reactant: CCOCC
Reactant: CC(C)c1cc(C(C)C)c(-c2ccccc2P2C(C)(C)CCC(=O)CC2(C)C)c(C(C)C)c1
Agent: C[Si](C)(C)C=[N+]=[N-]
Agent: Cl
Agent: FB(F)F
Product: CC(C)c1cc(C(C)C)c(-c2ccccc2P2C(C)(C)CCCC(=O)CC2(C)C)c(C(C)C)c1
Temperature: -78 °C
Reaction time: 0.08 h
Yield: 70.8 %

Procedure:
To a 250-mL round bottom flask equipped with a magnetic stir bar was added 2,2,7,7-tetramethyl-1-(2′,4′,6′-triisopropylbiphenyl-2-yl)phosphepan-4-one (1.24 g, 2.67 mmol, 1.0 equiv). The flask was sealed with a septum and purged with nitrogen gas for 10 minutes. The solid was dissolved with anhydrous, degassed dichloromethane (38 mL), and the solution was cooled to −78° C. Boron trifluoride diethyl etherate (507 μL, 4.00 mmol, 1.5 equiv) was added to the flask over the course of 3 minutes. After stirring the solution for 5 minutes, (trimethylsilyl)diazomethane (2.0 mL, 4.00 mmol, 1.5 equiv, 2 M in hexane) was added slowly over 3 minutes The bright yellow solution was stirred at −78° C. for an hour, then diluted with 1 M aqueous hydrochloric acid (50 mL). The slurry was warmed to room temperature overnight. The solution was charged into a separatory funnel and the phases were partitioned. The organic layer was collected, and the aqueous layer was washed with dichloromethane (2×20 mL). The combined organic fractions were then washed with aqueous saturated sodium bicarbonate (30 mL), dried over sodium sulfate, filtered, and concentrated via a rotary evaporator. Purification by silica gel column chromatography on an Isco CombiFlash system (120-g column; gradient: 1.5 column volumes heptane, ramp up to 90:10 heptane:ethyl acetate over 8.5 column volumes, hold at 90:10 for 4 column volumes) afforded the title compound as a white solid (905 mg, >99 area % by HPLC, 71% yield). 1H NMR (400 MHz, CDCl3) δ ppm 7.87-7.80 (m, 1H), 7.37-7.27 (m, 2H), 7.22 (ddd, J=4.2, 3.3, 1.9 Hz, 1H), 6.97 (dd, J=7.3, 1.8 Hz, 2H), 3.09-2.97 (m, 1H), 2.92 (dq, J=13.7, 6.9 Hz, 1H), 2.75-2.54 (m, 2H), 2.46-2.30 (m, 2H), 2.24 (dq, J=15.0, 5.7 Hz, 1H), 1.98-1.77 (m, 2H), 1.65 (tdd, J=13.5, 9.4, 3.9 Hz, 1H), 1.55-1.41 (m, 4H), 1.30 (d, J=6.9 Hz, 6H), 1.27 (t, J=4.5 Hz, 6H), 1.17 (d, J=6.8 Hz, 3H), 1.01 (d, J=6.6 Hz, 3H), 0.95 (d, J=6.7 Hz, 3H), 0.90 (d, J=12.2 Hz, 3H), 0.74 (d, J=16.4 Hz, 3H). 13C NMR (100 MHz, CDCl3) δ ppm 213.9, 148.5, 148.1, 147.4, 145.9, 145.6, 136.9 (d, J=2 Hz), 136.1 (d, J=5 Hz), 134.9, 134.6, 132.2 (d, J=7 Hz), 127.6, 124.9, 120.0 (d, J=14 Hz), 59.7 (d, J=27 Hz), 42.9 (d, J=12 Hz), 42.6, 36.9 (d, J=31 Hz), 36.0 (d, J=28 Hz), 34.3, 31.8 (d, J=14 Hz), 31.2 (d, J=4 Hz), 31.0, 30.3 (d, J=26 Hz), 29.0 (d, J=4 Hz), 27.1, 26.4-26.0 (m), 24.4 (d, J=7 Hz), 23.2-22.8 (m), 21.3 (d, J=7 Hz). 31P NMR (CDCl3, 202 MHz) δ ppm 10.5 (s). HRMS (TOF-ESI+) calcd for [M, C32H47OP]+ 478.3365, found 478.3369.