p-Toluenesulfonic acid → HCID 22084644, compound

HRID 1663578Notes

Reaction equation

HRID 1663578 reaction equation
C([N:8]1[C@@H:12]([C:13]2[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=2)[C@H:11]([CH3:19])[C:10](=[O:20])[O:9]1)C1C=CC=CC=1.[CH3:21]C1C=CC(S(O)(=O)=O)=CC=1>CO>[CH3:21][O:9][C:10](=[O:20])[CH:11]([CH3:19])[CH:12]([NH2:8])[C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1

Participants

4

Reactant 2

HCID 6101p-Toluenesulfonic acidHCID 66799533HCID 66799533, compound

Product 1

HCID 22084644HCID 22084644, compound

Reagents, catalysts & solvents 1

HCID 887MethanolSolvent

Procedure

Briefly, isoxazolidinone 40 (>99% ee) was converted to the amino acid 47 following the same procedure as set forth above. The mixture of amino acid 47 (0.07 g, 0.36 mmol) and pTSA (0.15 g, 0.79 mmol) was dissolved in dry methanol (5 mL) and refluxed for 12 hours. Methanol was removed under vacuum, and the residue was basified with 10% aqueous NaHCO3 solution. The precipitated aminoester was extracted with CH2Cl2 (3×5 mL). Organic extracts were combined and dried on anhydrous Na2SO4. Solvent was removed under vacuum to afford pure methyl ester 48 as an oily liquid. [α]D20=−31.7 (c 1.04, chloroform). Literature (Davies et al., J. Chem. Soc. Chem. Commun., 1153ff (1993), which is hereby incorporated by reference): [α]D20=−29.2 (c 1.00, chloroform) for absolute configuration (2R,3S). Therefore, absolute configuration of methyl ester and hence of isoxazolidinone was deemed to be (2R,3S).

Workup

  1. temperaturerefluxed for 12 hours
  2. customMethanol was removed under vacuum
  3. extractionThe precipitated aminoester was extracted with CH2Cl2 (3×5 mL)
  4. dry with materialdried on anhydrous Na2SO4
  5. customSolvent was removed under vacuum

Sources & evidence

ORD record
ord-d31f944a64ac4683b486993253a5468d
Source dataset
uspto-grants-2011_10
Patent number
US08034974B2

Reaction notes

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