p-Toluenesulfonic acid → Cbz-leucinal diethylacetal

HRID 977641Notes

Reaction equation

HRID 977641 reaction equation
[CH:1]([O:8][CH2:9][CH3:10])([O:5][CH2:6][CH3:7])OCC.[NH:11]([C:19]([O:21][CH2:22][C:23]1[CH:28]=[CH:27][CH:26]=[CH:25][CH:24]=1)=[O:20])[C@H:12](C=O)[CH2:13][CH:14]([CH3:16])[CH3:15].C1(C)C=CC(S(O)(=O)=O)=CC=1>C(O)C>[CH2:9]([O:8][CH:1]([O:5][CH2:6][CH3:7])[C@H:12]([CH2:13][CH:14]([CH3:16])[CH3:15])[NH:11][C:19]([O:21][CH2:22][C:23]1[CH:28]=[CH:27][CH:26]=[CH:25][CH:24]=1)=[O:20])[CH3:10]

Participants

5

Reactant 3

HCID 6101p-Toluenesulfonic acidHCID 31214Ethyl orthoformateHCID 10911911N-carbobenzoxy-L-leucinal

Product 1

HCID 54072519Cbz-leucinal diethylacetal

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Procedure

104 mL of triethyl orthoformate was added over a period of 30 min to a solution of CBZ-Leu-H (12 g) and p-toluenesulfonic acid (0.9 g) in 100 mL of anhydrous ethanol (EtOH). The mixture was stirred for 30 min, and then was evaporated and diluted with 500 mL of ether. The ether layer was washed consecutively with saturated solutions of NaHCO3 and sodium chloride. The yellowish brown semisolid was recrystallized from cold hexane to yield off-white needles of CBZ-Leucinal diethylacetal. 1H NMR (300 MHz, CDCl3) δ: 7.28(m, 5H), 5.03(s, 2H), 4.77(d, 1H), 4.27(d, 1H), 3.8(m, 1H), 3.63(m, 2H), 3.43(m, 2H), 1.6(dd, 2H), 1.30(m, 2H), 1.12(m, 6H), 0.83(d, 6H)

Workup

  1. customwas evaporated
  2. additiondiluted with 500 mL of ether
  3. washThe ether layer was washed consecutively with saturated solutions of NaHCO3 and sodium chloride
  4. customThe yellowish brown semisolid was recrystallized from cold hexane

Sources & evidence

ORD record
ord-392f9cdb9f4d4cb48789b90b5e6d6823
Source dataset
uspto-grants-1997_03
Patent number
US05614649

Reaction notes

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