N-Acetyl-D-alanine

Table 3 lists substrates (Formula 3), ee, and absolute stereochernical configuration of chiral products (Formula 2) prepared via asymmetric hydrogenation using chiral catalyst precursor, (S)-(+)-(2-{[(di-t-butyl-phosphanyl)-methyl]-methyl-phosphanyl}-2-methyl-propane)-(1, 5-cyclooctadiene)rhodium (I) tetrafluroborate (Formula 23). For each entry in Table 3, the catalyst precursor (0.01 mmole) was dissolved in degassed MeOH (1 mL) in a Griffin-Worden pressure vessel equipped with the attachments necessary to connect to a lecture bottle. The substrate (1 mmole) was first dissolved in MeOH (4 mL) and then delivered to the catalyst-MeOH solution via syringe. The vessel was sealed and pressurized to 50 psi H2. The time to the completion of reaction was determined by the cessation of H2 gas uptake. TABLE 3 Enantioselectivity of Chiral Compounds (Formula 2) Prepared via Asymmetric Hydrogenation of Prochiral Substrates (Formula 3) ExampleR1 R2 R3 R4 X ee Config. 5 AcNHCO2H H H Bond >99percent R 6 AcNHCO2H Ph H Bond >99percent R 7 AcNHCO2Me H H Bond >99percent R 8 AcNHCO2Me Ph H Bond >99percent R 9 AcNHCO2Me-C5H10- Bond 99percent R For each of the reactions shown in Table 3, enantiomeric excess was determined via chiral GC or chiral HPLC. Table 4 provides details of the ee methodology. To determine ee's for N-acetylalanine (Example 5) and N-acetylphenylalanine (Example 6), each compound was treated with trimethylsilyldiazomethane to convert it to its corresponding methyl ester, which was analyzed as provided in Example 7 or Example 8, respectively. Absolute stereochemical configuration was determined by comparing the signs of optical rotation with those of literature values: (S)-N-acetylalanine methyl ester [α]20D=-91.7° (c 2, H2O), J. P. Wolf III C. Neimann, Biochemistry 2:493 (1963); (S)-N-acetylphenylalanine methyl ester [α]20D=+16.4° (c 2, MeOH), B. D. Vineyard et al., J. Am. Chem. Soc. 99:5946 (1997); (S)-N-acetylcyclohexylglycine methyl ester [a]20D=-4.6° (c =0.13, EtOH), M. J. Burk et al., J. Am. Chem. Soc. 117:9375 (1995). TABLE 4 Conditions for Determining Enantiomeric Excess Examples 5 7 Examples 6 8 Method Capillary GC HPLC Capillary GC Column Chrompack Chiral- Daicel Chiralcel OJ Chirasil-L-Val L-Val (25 m) (25 m) Mobile Phase - 10percent IPA/hexane - Flow Rate - 1 mL/min - Column Temp. 120° C. 30° C. 145° C. Concentration - 2 mg/mL - Retention time-R 10.5 min 11.6 min 11.3 min Retention time-S 11.0 min 17.7 min 12.0 minAsymmetric hydrogenation of different unsaturated hydrocarbon compounds with chiral ligand 2 and [Rh(nbd)Example 12. Asymmetric hydrogenation of different unsaturated hydrocarbon compounds with chiral ligand 6 and [Rh(nbd)In a glove box, an autoclave with a 20 mL glass tube insert equipped with a magnetic stirring bar was charged with the hydrogenation substrate (1 mmol), anhydrous degassed solvent (7 mL) and the metal complex pre-catalyst (0.01 mmol). After 10 cycles of evacuation and filling with hydrogen, the autoclave was pressurised to an appropriate initial pressure of hydrogen. The reaction mixture was stirred at room temperature and after the appropriate time the autoclave was opened, the reaction mixture was filtered through silica gel, concentrated and the residue was analysed by enantioselective GC.In a glove box, an autoclave with a 20 mL glass tube insert equipped with a magnetic stirring bar was charged with the hydrogenation substrate (1 mmol), anhydrous degassed solvent (7 mL) and the metal complex pre-catalyst (0.01 mmol). After 10 cycles of evacuation and filling with hydrogen, the autoclave was pressurised to an appropriate initial pressure of hydrogen. The reaction mixture was stirred at room temperature and after the appropriate time the autoclave was opened, the reaction mixture was filtered through silica gel, concentrated and the residue was analysed by enantioselective GC.In a glove box, an autoclave with a 20 mL glass tube insert equipped with a magnetic stirring bar was charged with the hydrogenation substrate (1 mmol), anhydrous degassed solvent (7 mL) and the metal complex pre-catalyst (0.01 mmol). After 10 cycles of evacuation and filling with hydrogen, the autoclave was pressurised to an appropriate initial pressure of hydrogen. The reaction mixture was stirred at room temperature and after the appropriate time the autoclave was opened, the reaction mixture was filtered through silica gel, concentrated and the residue was analysed by enantioselective GC.In a glove box, an autoclave with a 20 mL glass tube insert equipped with a magnetic stirring bar was charged with the hydrogenation substrate (1 mmol), anhydrous degassed solvent (7 mL) and the metal complex pre-catalyst (0.01 mmol). After 10 cycles of evacuation and filling with hydrogen, the autoclave was pressurised to an appropriate initial pressure of hydrogen. The reaction mixture was stirred at room temperature and after the appropriate time the autoclave was opened, the reaction mixture was filtered through silica gel, concentrated and the residue was analysed by enantioselective GC.In a glove box, an autoclave with a 20 mL glass tube insert equipped with a magnetic stirring bar was charged with the hydrogenation substrate (1 mmol), anhydrous degassed solvent (7 mL) and the metal complex pre-catalyst (0.01 mmol). After 10 cycles of evacuation and filling with hydrogen, the autoclave was pressurised to an appropriate initial pressure of hydrogen. The reaction mixture was stirred at room temperature and after the appropriate time the autoclave was opened, the reaction mixture was filtered through silica gel, concentrated and the residue was analysed by enantioselective GC.In a glove box, an autoclave with a 20 mL glass tube insert equipped with a magnetic stirring bar was charged with the hydrogenation substrate (1 mmol), anhydrous degassed solvent (7 mL) and the metal complex pre-catalyst (0.01 mmol). After 10 cycles of evacuation and filling with hydrogen, the autoclave was pressurised to an appropriate initial pressure of hydrogen. The reaction mixture was stirred at room temperature and after the appropriate time the autoclave was opened, the reaction mixture was filtered through silica gel, concentrated and the residue was analysed by enantioselective GC.

Molecular Weight:131.13
XLogP3:-0.9
Hydrogen Bond Donor Count:2
Hydrogen Bond Acceptor Count:3
Rotatable Bond Count:2
Exact Mass:131.058243149
Monoisotopic Mass:131.058243149
Topological Polar Surface Area:66.4
Heavy Atom Count:9
Complexity:132
Defined Atom Stereocenter Count:1
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes