Reaction #166165

Reaction equation

(trimethylsilyl)diazomethane

2,2,6,6-tetramethyl-1-(2′,4′,6′-triisopropylbiphenyl-2-yl)phosphinan-4-one

Boron trifluoride diethyl etherate

phosphine

→

title compound

Yield 63.3%

2,2,7,7-Tetramethyl-1-(2′,4′,6′-triisopropylbiphenyl-2-yl)phosphepan-4-one

Yield 63.3%

Solvents

hydrochloric acid

Conditions

Workup

1. 1
   OtherTo a 40-mL scintillation vial equipped with a magnetic stir bar
2. 2
   OtherThe vial was sealed with
3. 3
   Othera septa-top cap
4. 4
   Otherpurged with nitrogen gas for 10 minutes The solid
5. 5
   workup.DISSOLUTIONwas then dissolved with anhydrous,
6. 6
   Otherdegassed dichloromethane (10 mL)
7. 7
   workup.ADDITIONIn a separate 250-mL round bottom flask was added anhydrous
8. 8
   Otherdegassed dichloromethane (36 mL) which
9. 9
   Otherwas transferred by cannula to the reaction flask over the course of 3 minutes
10. 10
    workup.STIRRINGwas stirred at −78° C. for an hour
11. 11
    TemperatureThe slurry was warmed to room temperature overnight
12. 12
    workup.ADDITIONThe solution was charged into a separatory funnel
13. 13
    Otherthe phases were partitioned
14. 14
    OtherThe organic layer was collected
15. 15
    Washwashed with aqueous saturated sodium bicarbonate (50 mL)
16. 16
    Dryingdried over sodium sulfate
17. 17
    Filtrationfiltered
18. 18
    Concentrationconcentrated in a rotary evaporator
19. 19
    OtherPurification of the crude colorless oil by silica gel column chromatography on an Isco CombiFlash system (120-g column

Procedure

To a 40-mL scintillation vial equipped with a magnetic stir bar was added 2,2,6,6-tetramethyl-1-(2′,4′,6′-triisopropylbiphenyl-2-yl)phosphinan-4-one (1.38 g, 3.06 mmol, 1 equiv). The vial was sealed with a septa-top cap and then purged with nitrogen gas for 10 minutes The solid was then dissolved with anhydrous, degassed dichloromethane (10 mL). In a separate 250-mL round bottom flask was added anhydrous, degassed dichloromethane (36 mL) which was cooled to −78° C. Boron trifluoride diethyl etherate (582 μL, 4.59 mmol, 1.5 equiv) was then added to the flask. The phosphine solution was transferred by cannula to the reaction flask over the course of 3 minutes using a positive pressure of nitrogen gas. After stirring the solution for 5 minutes, (trimethylsilyl)diazomethane (2.3 mL, 4.59 mmol, 1.5 equiv, 2 Min 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 washed with aqueous saturated sodium bicarbonate (50 mL), dried over sodium sulfate, filtered, and concentrated in a rotary evaporator. Purification of the crude colorless oil by silica gel column chromatography on an Isco CombiFlash system (120-g column; gradient: 1.5 column volumes heptane, ramp up to 98:2 heptane:methyl tert-butyl ether over 0.5 column volumes, hold at 98:2 for 2 column volumes, ramp up to 80:20 heptane:methyl tert-butyl ether over 8 column volumes, hold at 80:20 for 2 column volumes) afforded the title compound as a white solid (900 mg, 90 area % by HPLC, 63% yield). 1H NMR (400 MHz, CDCl3) δ ppm 8.00-7.90 (m, 1H), 7.43-7.29 (m, 2H), 7.28-7.21 (m, 1H), 7.00 (s, 2H), 3.10-2.86 (m, 2H), 2.73-2.37 (m, 5H), 2.34-2.18 (m, 1H), 1.95-1.77 (m, 1H), 1.31 (d, J=6.9 Hz, 5H), 1.23 (d, J=6.8 Hz, 3H), 1.20 (d, J=6.8 Hz, 3H), 1.15 (d, J=6.6 Hz, 3H), 1.10 (d, J=6.4 Hz, 3H), 1.08-1.03 (m, 4H), 1.02-0.98 (m, 4H), 0.95 (d, J=6.7 Hz, 3H). 13C NMR (100 MHz, CDCl3) δ ppm 211.3, 148.6 (d, J=35 Hz), 147.5, 145.8 (d, J=16 Hz), 136.1 (d, J=6 Hz), 135.5 (d, J=31 Hz), 134.3 (d, J=2 Hz), 132.6 (d, J=7 Hz), 127.8, 125.5, 120.1 (d, J=5 Hz), 56.5 (d, J=10 Hz), 41.5, 36.3 (d, J=10 Hz), 35.0 (d, J=24 Hz), 34.3, 33.3 (d, J=27 Hz), 32.2 (d, J=31 Hz), 31.9 (dd, J=6, 2 Hz), 30.7, 29.5 (d, J=5 Hz), 29.3 (d, J=3 Hz), 26.7 (d, J=33 Hz), 24.3 (d, J=8 Hz), 22.9 (d, J=9 Hz). 31P NMR (CDCl3, 202 MHz) δ ppm 18.3 (s). HRMS (TOF-ESI+) calcd for [M, C31H45OP]+ 464.3208. Found 464.3216.

Source