1-O-tert-butyl 2-O-ethyl (2S)-5-hydroxypyrrolidine-1,2-dicarboxylate

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

Procedure: A solution of 10.0 g of 167 (38.9 mmol) in 100 ml of anhydrous THF was cooled to −78° C. and added very slow with 85.5 ml of DIBAL-H (85.5 mmol, 2.2 eq., 1 M/THF). After one hour, the reaction was terminated by adding 10 ml of isopropanol at low temperature, followed by addition of 240 ml of a K—Na tartrate solution (1.77 M), and the mixture was slowly thawed, initially to 0° C. and subsequently to RT. The resulting phases were separated, the organic phase was extracted with 3×200 ml of MTBE, and the combined organic phases were washed with 100 ml of saturated NaCl solution. After drying over MgSO4, the solvent was removed to obtain 9.69 g of 205 (37.4 mmol, 96%) as a yellowish oily residue which was further reacted without purification. For analytical purposes, a small sample was purified using silica gel column chromatography (EE/CH 1:1). the reaction was terminated by adding 10 ml of isopropanol at low temperature followed by addition of 240 ml of a K—Na tartrate solution (1.77 M) was slowly thawed, initially to 0° C. and subsequently to RT The resulting phases were separated the organic phase was extracted with 3×200 ml of MTBE the combined organic phases were washed with 100 ml of saturated NaCl solution After drying over MgSO4 the solvent was removed

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

Procedure: A solution of 10.0 g of 167 (38.9 mmol) in 100 ml of anhydrous THF was cooled to −78° C. and added very slow with 85.5 ml of DIBAL-H (85.5 mmol, 2.2 eq., 1 M/THF). After one hour, the reaction was terminated by adding 10 ml of isopropanol at low temperature, followed by addition of 240 ml of a K—Na tartrate solution (1.77 M), and the mixture was slowly thawed, initially to 0° C. and subsequently to RT. The resulting phases were separated, the organic phase was extracted with 3×200 ml of MTBE, and the combined organic phases were washed with 100 ml of saturated NaCl solution. After drying over MgSO4, the solvent was removed to obtain 9.69 g of 205 (37.4 mmol, 96%) as a yellowish oily residue which was further reacted without purification. For analytical purposes, a small sample was purified using silica gel column chromatography (EE/CH 1:1). the reaction was terminated by adding 10 ml of isopropanol at low temperature followed by addition of 240 ml of a K—Na tartrate solution (1.77 M) was slowly thawed, initially to 0° C. and subsequently to RT The resulting phases were separated the organic phase was extracted with 3×200 ml of MTBE the combined organic phases were washed with 100 ml of saturated NaCl solution After drying over MgSO4 the solvent was removed