Reaction #1747885

Reaction equation

47

(3S,4R)-4-tert-Butoxycarbonylamino-5-methyl-3-(tert-butyldimethyl-silanyloxy)hexanoic Acid Methyl Ester

NaOH

→

acid 48

(3S,4R)-4-tert-Butoxycarbonylamino-5-methyl-3-(tert-butyldimethyl-silanyloxy)hexanoic Acid

Solvents

THF MeOH

Conditions

Workup

1. 1
   Otherovernight
2. 2
   Otherat rt
3. 3
   ConcentrationThe reaction mixture was concentrated
4. 4
   workup.ADDITIONdiluted with H2O (20 mL)
5. 5
   Temperaturecooled to 0° C.
6. 6
   Extractionextracted with EtOAc (3×20 mL)
7. 7
   WashThe combined organic layers were washed with NaCl (50 mL, sat)
8. 8
   Dryingdried (Na2SO4)
9. 9
   Filtrationfiltered
10. 10
    Otherevaporated

Procedure

To a solution of 47 (500 mg, 1.28 mmol) in 25 mL of THF/MeOH (1:1), cooled to 0° C., 1N NaOH solution (25 mL) was added. The reaction was stirred at 0° C. for 2 h and then overnight at rt. The reaction mixture was concentrated and diluted with H2O (20 mL), cooled to 0° C., acidified to pH 2 with 1N KHSO4 solution, and extracted with EtOAc (3×20 mL). The combined organic layers were washed with NaCl (50 mL, sat), dried (Na2SO4), filtered and evaporated. The resulting acid 48 was obtained as a colorless oil (1.76 g, 86%) and used directly in the next step. 1H-NMR (500 MHz, CDCl3): 0.06 (s, 6H), 0.84-0.95 (m, 15H), 1.43 (s, 9H), 2.01-2.11 (m, 1H), 2.53 (m, 1H), 2.64 (m, 1H), 3.53-3.58 (m, 1H), 4.10-4.14 (m, 1H), 3.65 (s, 3H), 4.17-4.19 (m, 1H), 4.51-4.54 and 6.29-6.31 (m, 1H).

Source