Dicyclohexylcarbodiimide → (3R)-1-Benzyl-3-ethylpiperazine-2,5-dione

HRID 1064563Notes

Reaction equation

HRID 1064563 reaction equation
[C:1]([NH:8][C@H:9]([CH2:13][CH3:14])[C:10]([OH:12])=O)([O:3]C(C)(C)C)=O.[CH2:15]([N:17]([CH2:22][C:23]1[CH:28]=[CH:27][CH:26]=[CH:25][CH:24]=1)CC(O)=O)C.C1(N=C=NC2CCCCC2)CCCCC1>ClCCl>[CH2:13]([C@H:9]1[NH:8][C:1](=[O:3])[CH2:15][N:17]([CH2:22][C:23]2[CH:28]=[CH:27][CH:26]=[CH:25][CH:24]=2)[C:10]1=[O:12])[CH3:14]

Participants

5

Reactant 3

HCID 10868DicyclohexylcarbodiimideHCID 2755936(2R)-2-[(2-methylpropan-2-yl)oxycarbonylamino]butanoic acidHCID 19755290N-Benzyl-N-ethylglycine

Product 1

HCID 40423500(3R)-1-Benzyl-3-ethylpiperazine-2,5-dione

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Conditions

Temperature
12.5 °C

Procedure

To a stirred solution of (R)—N-BOC-2-aminobutyric acid (3.36 g) and ethyl N-benzylglycine (4.52 g) in dichloromethane (50 ml) at 15° C. was added dicyclohexylcarbodiimide (3.59 g). The temperature was maintained at 10-15° C. for a further 2 h and then allowed to stir at ambient temperature for a further 16 h. The mixture was filtered and the mother liquor collected and solvent evaporated under reduced pressure. The residue was re-dissolved in dichloromethane (20 ml) and hydrogen chloride gas passed through the mixture for 20 minutes. The mixture was quenched with aq. saturated sodium bicarbonate solution and extracted with ethyl acetate, collected, dried (MgSO4) and solvent evaporated under reduced pressure to leave a colourless oil. This was purified by crystallisation from ether/iso-hexane mixtures to give the subtitle compound as a white solid. Yield: 1.35 g

Workup

  1. filtrationThe mixture was filtered
  2. customthe mother liquor collected
  3. customsolvent evaporated under reduced pressure
  4. dissolutionThe residue was re-dissolved in dichloromethane (20 ml)
  5. waithydrogen chloride gas passed through the mixture for 20 minutes
  6. customThe mixture was quenched with aq. saturated sodium bicarbonate solution
  7. extractionextracted with ethyl acetate
  8. customcollected
  9. dry with materialdried (MgSO4) and solvent
  10. customevaporated under reduced pressure
  11. customto leave a colourless oil
  12. customThis was purified by crystallisation from ether/iso-hexane

Sources & evidence

ORD record
ord-0cca35c0d93041abbd6f5d4580e13de1
Source dataset
uspto-grants-2005_11
Patent number
US06969713B2

Reaction notes

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