Acetic acid, 2-(triphenylphosphoranylidene)-, ethyl ester → (R,E)-ethyl 5-(tert-butoxycarbonylamino)hex-2-enoate

HRID 529548Notes

Reaction equation

HRID 529548 reaction equation
O=[CH:2][CH2:3][C@H:4]([NH:6][C:7](=[O:13])[O:8][C:9]([CH3:12])([CH3:11])[CH3:10])[CH3:5].[C:14]([CH:19]=P(C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1)([O:16][CH2:17][CH3:18])=[O:15]>C1COCC1>[C:9]([O:8][C:7]([NH:6][C@H:4]([CH3:5])[CH2:3]/[CH:2]=[CH:19]/[C:14]([O:16][CH2:17][CH3:18])=[O:15])=[O:13])([CH3:12])([CH3:11])[CH3:10]

Participants

4

Reactant 2

HCID 70670Acetic acid, 2-(triphenylphosphoranylidene)-, ethyl esterHCID 25231755tert-butyl N-[(2R)-4-oxobutan-2-yl]carbamate

Product 1

HCID 86706226(R,E)-ethyl 5-(tert-butoxycarbonylamino)hex-2-enoateYield 80.4%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Procedure

To a solution of (R)-tert-butyl 4-oxobutan-2-ylcarbamate (1.54 g, 8.22 mmol) in THF (25 mL) at rt was added (carbethoxymethylene)triphenylphosphorane (6.30 g, 18.1 mmol) in portions. The resulting clear solution was stirred at rt under argon for 3 days. The reaction mixture was concentrated and the oily residue was purified using silica gel chromatography (ISCO system) eluting with a gradient of 0-60% EtOAc/Hex to give (R,E)-ethyl 5-(tert-butoxycarbonylamino)hex-2-enoate (1.70 g, 6.61 mmol, 80% yield) as a colorless oil. 1H NMR (400 MHz, CDCl3) δ ppm 6.91 (dt, J=15.3, 7.5 Hz, 1H), 5.92-5.82 (m, 1H), 4.37 (s, 1H), 4.19 (q, J=7.1 Hz, 2H), 3.83 (s, 1H), 2.37 (t, J=6.6 Hz, 2H), 1.44 (s, 9H), 1.29 (t, J=7.1 Hz, 3H), 1.15 (d, J=6.7 Hz, 3H).

Workup

  1. concentrationThe reaction mixture was concentrated
  2. customthe oily residue was purified
  3. washeluting with a gradient of 0-60% EtOAc/Hex

Sources & evidence

ORD record
ord-a199d04452e44054a22ecb80c731ccf8
Source dataset
uspto-grants-2016_05
Patent number
US09346852B2

Reaction notes

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