ethyl (2R)-2-hydroxy-2-phenylacetate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Ethyl phenylglyoxylate (1.6 mmol) was asymmetrically reduced in the same manner as in Example 6, except that DMF was used as the reaction medium, giving 0.25 g of ethyl (R)-(-)-2-hydroxy-2-phenylacetate, having specific rotation [α]D20 of 38.8° (cl. 00, CHCl3). The synthesis yield was 80% and the optical yield was 75% e.e.

Conditions: temp:70.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a dispersion of 0.43 g (11.3 mmol) of sodium borohydride in THF (35 ml), there was added 1.70 g (11.3 mmol) of L-(+)-tartaric acid, and the mixture was heated under reflux for four hours in an oil bath at 70° C. with stirring. The resulting mixture was cooled in a cryostat at -20° C., a solution of 0.5 g (2.8 mmol) of ethyl phenylglyoxylate in THF (5 ml) was added dropwise over a period of ten minutes, and stirring was continued for 19 hours. The reaction mixture was treated in the same manner as in Example 6, giving 0.44 of ethyl (R)-(-)-2-hydroxy-2-phenylacetate, having a specific rotation [α]D16 of -109° (cl. 00, CHCl3). the mixture was heated The resulting mixture was cooled in a cryostat at -20° C. stirring The reaction mixture was treated in the same manner as in Example 6

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of 1.70 g (11.3 mmol) of L-(+)-tartaric acid in 35 ml of THF was cooled in a cryostat at -20° C., and a solution of 0.5 g (2.8 mmol) of ethyl phenylglyoxylate in THF (5 ml) was added. To the resulting solution, there was further added 0.43 g (11.3 mmol) of sodium borohyride, all at once and with stirring, and the mixture was stirred for 24 hours. The reaction mixture was cooled in an ice bath, 20 ml of 1N HCl was added, and stirring was continued for 15 minutes. After distilling off THF under reduced pressure, the aqueous layer was extracted twice with ethyl acetate (30 ml and 20 ml), and the combined extract was washed first with 20 ml of a saturated aqueous solution of sodium chloride, and then dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure from the dried solution, and the residue was purified by silica gel column chromatography, giving 0.43 g of ethyl (R)-(-)-2-hydroxy-2-phenylacetate as an ethyl acetate:n-hexane fraction(1:5). Its specific rotation [α]D16 was -108.4° (cl. 12, CHCl3). The synthesis yield was 85% and the optical yield was 85% e.e (see Reference 7). the mixture was stirred for 24 hours The reaction mixture was cooled in an ice bath stirring After distilling off THF under reduced pressure the aqueous layer was extracted twice with ethyl acetate (30 ml and 20 ml) the combined extract was washed first with 20 ml of a saturated aqueous solution of sodium chloride dried over anhydrous magnesium sulfate The solvent was distilled off under reduced pressure from the dried solution the residue was purified by silica gel column chromatography

Conditions: temp:40.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of 31.4 g of t-butyldimethylsilyl chloride in 200 ml of dimethylformamide was added dropwise to a solution of 25 g of ethyl (R)-(-)-mandelate and 28.4 g of imidazole in 600 ml of anhydrous dimethylformamide, and the resulting mixture was stirred overnight at 40° C. The dimethylformamide solvent was then removed by distillation under reduced pressure, and the residue was mixed with water and then extracted with ethyl acetate. The extract was dried over anhydrous sodium sulfate, and the solvent was then removed by distillation under reduced pressure. The resulting residue was purified by column chromatography through silica gel, using a 1:10 by volume mixture of ethyl acetate and hexane as the eluent. The title compound was obtained as a liquid, boiling at 129° C./3.5 mmHg (466 Pa) by distillation in vacuo. The dimethylformamide solvent was then removed by distillation under reduced pressure the residue was mixed with water extracted with ethyl acetate The extract was dried over anhydrous sodium sulfate the solvent was then removed by distillation under reduced pressure The resulting residue was purified by column chromatography through silica gel by volume mixture of ethyl acetate and hexane as the eluent

Conditions: temp:40.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of 31.4 g of t-butyldimethylsilyl chloride in 200 ml of dimethylformamide was added dropwise to a solution of 25 g of ethyl (R)-(-)-mandelate and 28.4 g of imidazole in 600 ml of anhydrous dimethylformamide, and the resulting mixture was stirred overnight at 40° C. The dimethylformamide solvent was then removed by distillation under reduced pressure, and the residue was mixed with water and then extracted with ethyl acetate. The extract was dried over anhydrous sodium sulfate, and the solvent was then removed by distillation under reduced pressure. The resulting residue was purified by column chromatography through silica gel, using a 1:10 by volume mixture of ethyl acetate and hexane as the eluent,. The title compound was obtained as a liquid, boiling at 129° C./3.5 mmHg (466 Pa) by distillation in vacuo. [α]D23 -40.8° (c=1.07, chloroform) The dimethylformamide solvent was then removed by distillation under reduced pressure the residue was mixed with water extracted with ethyl acetate The extract was dried over anhydrous sodium sulfate the solvent was then removed by distillation under reduced pressure The resulting residue was purified by column chromatography through silica gel by volume mixture of ethyl acetate and hexane as the eluent