3,4-dimethylpentanoic acid

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

Procedure: HATU (0.872 g, 2.3 mmol, 1 eq) and TEA (0.647 ml, 4.6 mmol, 2 eq) were added to an ice-cooled solution of 3,4-dimethylpentanoic acid (300 mg, 2.3 mmol, 1 eq) in THF (26 ml), and stirring was carried out for 15 min. (3R)-3-Amino-2,3-dihydro-1H-indene-5-carboxylic acid methyl ester hydrochloride (A-01) (0.786 g, 3.5 mmol, 1.5 eq) was added to the reaction solution, and the mixture was then stirred overnight at RT. The reaction solution was diluted with ethyl acetate, washed with sat. sodium hydrogen carbonate solution and sat. NaCl solution, dried over magnesium sulfate and concentrated under reduced pressure. After purification by column chromatography (silica gel, cyclohexane:ethyl acetate 2:1), the desired product was obtained. Yield: 87% (0.61 g) the mixture was then stirred overnight at RT washed with sat. sodium hydrogen carbonate solution and sat. NaCl solution dried over magnesium sulfate concentrated under reduced pressure After purification by column chromatography (silica gel, cyclohexane:ethyl acetate 2:1)