Page 207 - Catalysts for Fine Chemical Synthesis Vol 1 - Robert & Poignant

asymmetric hydrogenation of carbon±carbon double bonds 195

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12.7.1 PREPARATION OF (R,R)-1,1 -BIS (a-HYDROXYPROPYL)
FERROCENE

OH
CHO Ph Me
Et 2 Zn Et
Fe + HS N Fe
ether
Et
CHO
(5mol%) OH

Materials and equipment
. 1,1 -Ferrocenedicarboxaldehyde, 8.30 g [26,27]
0
. Diethylzinc (1.1 M in toluene), 28.7 mL
. (1R,2S)-1-Phenyl-2-(1-piperidinyl)propane-1-thiol, 400 mg
. Diethyl ether, 115 mL
. 1 M Hydrochloric acid
. Diethyl ether
. Brine
. Magnesium sulfate
. Silica gel (230±400 mesh)

. 250 mL Round-bottomed flask with a magnetic stirring bar
. Magnetic stirrer
. Temperature controller
. Separatory funnel, 250 mL
. Glass filter (3G3)
. Rotatory evaporator
. Glass column

Procedure
1. In a degassed 250 mL round-bottomed flask equipped with a magnetic stirring
bar were placed 1,1 -ferrocenedicarboxaldehyde (8.30 g), (1R,2S)-1-phenyl-2-
0
(1-piperidinyl)propane-1-thiol (400 mg) and dry diethyl ether (115 mL). Di-
ethylzinc in toluene (1.1 M, 28.7 mL) was added dropwise to the mixture at
0 8C. The reaction mixture was stirred at 0 8C for 10 hours.
2. After the period, the reaction was quenched by adding a solution of 1 M HCl
with vigorous stirring at 0 8C until no more ethane gas was generated. The
white inorganic material was removed by filtration over a glass filter.
3. The organic layer was separated and the aqueous layer was extracted with
ether (3 30 mL). The combined organic layer was washed with brine, dried
over magnesium sulfate, filtered and concentrated using a rotatory evapor-
ator to give a crude black residue.