HCID 10977723, compound → HCID 2734514, compound

Temperature

0 °C

A solution of the tert-butylamnine salt of 2-isopropylidenesuccinic acid 1-methyl ester (162 g, 0.66 mol) in methanol (800 mL) was transferred to a 2 L high pressure hydrogenation vessel and degassed by pressurizing and venting four times with 10 bar of hydrogen. The vessel was then cooled to 0° C. and a solution of [Rh(COD)(S,S)-Me-BPE]OTf(0.80 g, 0.0013 mol) in methanol (10 mL) was added through the solvent port. The reaction was purged again with hydrogen and stirred at 0° C. under a pressure of hydrogen of 10-7 bar. After 22 hours, the temperature was allowed to raise to room temperature, the vessel was vented in a fume hood, the reaction mixture was transferred to a round-bottomed flask and the solvent was evaporated under reduced pressure. A sample (1 g) of the resulting solid residue was partitioned between HCl 2N (5 mL) and ethyl acetate (5 mL). The organic layer was dried over MgSO4 and evaporated to give 2-(S)-isopropylsuccinic acid 1-methyl ester, ee 96% by GC. The bulk residue was suspended in ethyl acetate (600 mL) and stirred at room temperature for 48 hours, then collected and dried under vacuum to give 154 g of the tert-butylamine salt of 2-(S)-isopropylsuccinic acid monomethyl ester (yield: 94%). A sample (1 g) of the salt was worked up and analyzed as above, indicating an enantiomeric excess of 99% for the free acid.

1. customdegassed
2. customThe reaction was purged again with hydrogen
3. temperatureto raise to room temperature
4. customthe reaction mixture was transferred to a round-bottomed flask
5. customthe solvent was evaporated under reduced pressure
6. customA sample (1 g) of the resulting solid residue was partitioned between HCl 2N (5 mL) and ethyl acetate (5 mL)
7. dry with materialThe organic layer was dried over MgSO4
8. customevaporated

ORD record

ord-f7909be7a2b049458887e14c1a2c9f57

Source dataset

uspto-grants-2001_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06207853B1