Page 220 - Catalysts for Fine Chemical Synthesis Vol 1 - Robert & Poignant

208 hydrolysis, oxidation and reduction

. 100 mL Round-bottomed flask with an argon inlet
. Two syringes (5 mL, 1 mL)
. Separatory funnel, 500 mL
. Magnetic stirring bar
. Magnetic stirrer
. Rotatory evaporator
. Chromatography column

Procedure
1. In a 100 mL round-bottomed flask with an argon inlet equipped with a
magnetic stirring bar (S,S)-1,1 -bis(a-N,N-dimethylaminophenylmethyl)fer-
0
rocene (480 mg) was dissolved in diethyl ether (20 mL) under argon and
cooled in an ice bath to 0 8C. t-BuLi (1.60 M in pentane, 1.99 mL) was
added within 10 minutes via a syringe (after a few minutes the colour of
the solution turned from yellow to dark red). After 1 hour of stirring,
chlorodiphenylphosphine (0.67 mL) was added at 0 8C via a syringe and
the resulting mixture was stirred for 4 hours at room temperature.
2. After addition of saturated sodium hydrogen carbonate solution (20 mL) the
organic layer was separated and the aqueous layer extracted with diethyl
ether (3 70 mL). The combined organic layers were dried over magnesium
sulfate, filtrated and the solvent removed using a rotatory evaporator to give
a yellow oil.
3. The crude product was purified by column chromatography (n-pentane:
diethyl ether 1:1) immediately after isolation and dried under vacuum
yielding (aS, a S)-1,1 -bis(a-N,N-dimethylaminophenyl-methyl)-(R,R)-1,1 -
0
0
0
bis(diphenylphosphino)-ferrocene (392 mg, 0.48 mmol, 45 %) as a yellow
solid (mp 245±246 8C).
It is important that the crude product is purified as quickly as possible,
because in the crude reaction mixture it tends to become oxidized and/or
degrade with time.
1 H-NMR (300 MHz, CDCl 3 ): d 7.35±7.10 (m, 30 H), 4.52 (s, br, 2 H),
4.39 (s, br, 2 H), 3.29 (s, br, 2 H), 3.15 (s, br, 2 H), 1.51 (s, 12 H).
13 C-NMR (75 MHz, CDCl 3 ): d 139.99, 139.68 (d, J 6.8 Hz), 137.84 (d, J
10.1 Hz), 134.77 (d, J 23.0 Hz), 132.38 (d, J 13.4 Hz), 128.55, 128.49, 127.97
(d, J 8.0 Hz), 127.92, 127.44 (d, J 7.0 Hz), 127.30, 126.59, 98.09 (d, J
22.5 Hz), 76.51 (d, J 10.0 Hz), 73.13, 72.88 (d, J 5.2 Hz), 71.57, 68.27 (d, J
10.1 Hz), 42.00.
31
P-NMR (81 MHz, CDCl 3 ): d ÿ 23:89.