Methanol → alpha-Methylhydrocinnamic acid
Reaction equation
C[C:2]1[CH:12]=[CH:11][CH:10]=[CH:9][C:3]=1[CH:4]=[CH:5][C:6]([OH:8])=[O:7].[H][H].[CH3:15]O>>[CH3:15][CH:5]([CH2:4][C:3]1[CH:2]=[CH:12][CH:11]=[CH:10][CH:9]=1)[C:6]([OH:8])=[O:7]Participants
Procedure
0.41 g (2.53 mmol) of 2-methylcinnamic acid and 5 ml of degassed methanol are introduced in succession into a Schlenk vessel filled with argon. A catalyst solution consisting of 4.73 mg (0.01265 mmol) of [Rh(norbornadiene)2]BF4, 8.77 mg (0.0133 mmol) of ligand A and 5 ml of degassed methanol is prepared in a second Schlenk vessel filled with argon. This solution and the catalyst solution are then transferred in succession by means of a steel capillary into a 50 ml autoclave filled with argon. The ratio of substrate/catalyst is 200. The autoclave is closed and a pressure of 5 bar is set by means of 4 flushing cycles (pressurization to 10 bar of hydrogen). The autoclave is thermostated at 25° C. and the reaction is started by switching on the stirrer. The reactor is stirred for 19 hours. After opening the autoclave, a reddish reaction solution is isolated. The conversion is quantitative (determined by means of GC and 1H-NMR). Removal of the solvent on a rotary evaporator gives a quantitative yield of 2-methyl-3-phenylpropionic acid having an enantiomeric purity of 29% ee (determined by means of HPLC after conversion into the methyl ester; column: Chiracel OB.).
Workup
- additionfilled with argon
- customis prepared in a second Schlenk vessel
- additionfilled with argon
- additionfilled with argon
- customThe autoclave is closed
- customat 25° C.
- customa reddish reaction solution is isolated
- customRemoval of the solvent
- customon a rotary evaporator
Sources & evidence
- ORD record
- ord-b806b0fab7cb4fb0995995ca40b9d3e3
- Source dataset
- uspto-grants-2010_03
- Patent number
- US07671225B2
Reaction notes
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