Page 199 - Catalysts for Fine Chemical Synthesis Vol 1 - Robert & Poignant

asymmetric hydrogenation of carbon±carbon double bonds 187

Materials and equipment
[9]
. 5-Methylene-1,3-dioxolane-2-one , 0.25 g, 1.95 mmol
. ((R)-BiNAP)Ru(O 2 CCF 3 ) 2 [10] , 9 mg, 0.01 mmol
. Dry and degassed dichloromethane, 15 mL

. 125 mL Stainless steel autoclave with a mechanical stirrer
. 50 mL Round bottomed flask
. Rotary evaporator
. Kugelrohr apparatus

Procedure
1. The 125 mL stainless steel autoclave was flushed with nitrogen. The 5-
methylene-1,3-dioxolane-2-one, the ruthenium catalyst and dichloro-
methane (10 mL) were placed in the autoclave under a nitrogen atmosphere.
2. The autoclave was sealed, flushed with hydrogen and pressurized with 10 MPa
of hydrogen. The mixture was stirred for 18 hours at 20 8C under 10 MPa of
hydrogen.
3. Once the autoclave was depressurized, the solution was poured into a 50 mL
round bottomed flask and the autoclave rinsed with dichloromethane
(5 mL). The solvent was removed by using a rotary evaporator.
4. The hydrogenated carbonate can be recovered free of ruthenium catalyst by
sublimation under reduced pressure using a Kugelrohr apparatus (bp 70 8C,
1.5 mmHg).
This procedure has been scaled up to provide 2 g of 4,4,5-trimethyl-1,3-
dioxolane-2-one.
The optical purity can be determinated by using GC with a chiral Lipo-
dex capillary column (25 m 0.25 mm).

12.5.2 SYNTHESIS OF (S)-2-METHYL-2,3-BUTANEDIOL

H H
K 2 CO 3
O O HO OH
MeOH, 608C, 2.5 h
O 87%

Materials and equipment

. 4,4,5-Trimethyl-1,3-dioxolane-2-one, 0.17 g, 1.34 mmol
. Potassium carbonate, 0.27 g, 2.0 mmol
. Dry methanol, 10 mL
. Diethyl ether, 10 mL
. Saturated solution of NH 4 Cl, 5 mL
. Magnesium sulfate