Tetrahydrofuran → tert-Butyl acetate

HRID 365278Notes

Reaction equation

HRID 365278 reaction equation
C1N=CN(C(N2C=[N:11][CH:10]=[CH:9]2)=O)C=1.[Li:13][CH2:14][C:15]([O:17][C:18]([CH3:21])([CH3:20])[CH3:19])=[O:16].[CH2:22]1COCC1>>[Li+:13].[CH3:9][CH:10]([N-:11][CH:18]([CH3:20])[CH3:21])[CH3:22].[C:15]([O:17][C:18]([CH3:21])([CH3:20])[CH3:19])(=[O:16])[CH3:14]

Participants

5

Reactant 3

HCID 8028Tetrahydrofuran2×HCID 682631,1'-CarbonyldiimidazoleHCID 178506879HCID 178506879, compound

Product 2

HCID 10908tert-Butyl acetateHCID 2724682Lithium diisopropylamide

Conditions

Temperature
0 °C

Procedure

Cbz-D-Dpa-Pro-OH (0.265 g, 5.6×10-4 mol) was dissolved in THF, and cooled to 0° C. in an ice bath. CDI (N,N'-carbonyldiimidazole, 0.109 g, 6.7×10-4 mol, 1.2 mol eq) was added with stirring to the above solution, and left for 30 min at 0° C., followed by 2 h at room temperature. The mixture was added dropwise to a precooled solution of tertiary butyl lithioacetate (formed from the addition of LDA {0.901 cm3 of 2M solution, 3.2 mol eq in THF} to tertiary butyl aceate {0.21 g, 0.243 cm3, 3.2 mol eq}) over 1 h at -78° C. When the addition had finished, the reaction mixture was kept at this temperature for 15 min, quenched with 1M HCl (64 cm3), allowed to warm to 0° C., acidified to pH 3, and extracted with CHCl3 (3×100 cm3). The combined CHCl3 layer was washed with saturated brine, dried over anhydrous Na2SO4, and concentrated under reduced pressure on a rotary evaporator. Chromatographic purification (Sephadex® LH20, MeOH) of the oily residue provided (0.215 g, 67%) of the desired compound as a yellow crystalline solid. 1H(CDCl3) N.M.R.--good; 13C(CDCl3) N.M.R.--good; ESMS(MeOH): m/z(%) 593 (M+Na, 100), 1164 (2M+H+Na).

Workup

  1. waitfollowed by 2 h at room temperature

Sources & evidence

ORD record
ord-b84411f7a67840b5bb5f4876acbb9fe4
Source dataset
uspto-grants-2000_10
Patent number
US06127340

Reaction notes

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