Citric Acid → HCID 11492787, compound

Participants

Reaction Steps

After adding approximately 3.5 g LiCl bei −78° C. to a solution of 14.092 g (57.64 mmol, 1.0 eq) of the protected proline 103, 138 ml (86.46 mmol, 1.5 eq, 0.625 M) LDA in THF were dropped in over the course of 60 min. The solution was stirred for 30 min at this temperature, and then 15 ml (241.85 mmol, 4.0 eq) HCOOMe was very slowly dropped in over 120 min. The solution was stirred for another 30 min at −78° C., and then brought to a temperature of −40° C. over the course of 1 h. 120 ml of a 10% citric acid solution in water was then added, the substance was extracted 3× with 120 ml MTBE respectively, and the combined organic phases were washed with 500 ml saturated NaCl solution, dried over magnesium sulfate, and the solvent was removed under reduced pressure. Chromatography on silica gel with EtOAc/CyHex 1:4 as eluent yielded 10.388 g (38.12 mmol, 66%) of the product 104 as white solid.

Provenance & Evidence