Hydrochloric Acid → tert-butyl 3-tert-butyl-L-tyrosinate

HRID 369826Notes

Reaction equation

HRID 369826 reaction equation
[CH3:1][C:2](=[CH2:4])[CH3:3].[C:5]([C:9]1[CH:10]=[C:11]([CH:18]=[CH:19][C:20]=1[OH:21])[CH2:12][C@@H:13]([C:15]([OH:17])=[O:16])[NH2:14])([CH3:8])([CH3:7])[CH3:6].Cl.C([O-])(O)=O.[Na+]>O.CO.C(Cl)Cl.O1CCOCC1>[C:2]([O:17][C:15](=[O:16])[C@H:13]([CH2:12][C:11]1[CH:18]=[CH:19][C:20]([OH:21])=[C:9]([C:5]([CH3:7])([CH3:6])[CH3:8])[CH:10]=1)[NH2:14])([CH3:3])([CH3:1])[CH3:4]

Participants

9

Reactant 4

HCID 313Hydrochloric AcidHCID 8255IsobutyleneHCID 516892Sodium BicarbonateHCID 206376913-tert-butyl-L-tyrosine

Product 1

HCID 57240609tert-butyl 3-tert-butyl-L-tyrosinateYield 44%

Reagents, catalysts & solvents 4

HCID 887MethanolSolventHCID 962WaterSolventHCID 6344DichloromethaneSolventHCID 312751,4-DioxaneSolvent

Procedure

To a 250 mL round bottomed flask equipped with a magnetic stirrer were added 30 mL of isobutylene (condensed at -78° C.), 1.30 g of 3-tert-butyl-L-tyrosine.HCl, 60 mL of 1,4-dioxane, and 0.5 mL of concentrated H2SO2. The flask was sealed with a rubber septum and wired shut. After stirring at RT for 18 h, the flask was vented and the contents poured into a solution of 10 g of NaHCO3 in 150 mL of water. The mixture was subjected to rotary evaporation to remove isobutylene. An emulsion resulted which was extracted with EtOAc (4×40 mL). The combined extracts were washed with 5% aqueous NaHCO3 (3×50 mL), dried over anhydrous MgSO4, and concentrated to give a light yellow foam. Analysis of the product by tlc (SiO2, 95:5 CH2Cl2 :MeOH) indicated major and minor components at Rf =0.45 and 0.49 respectively. The Rf =0.45 product was isolated by flash chromatography on silica gel (95:5 CH2Cl2 :MeOH) to afford 0.61 g (44%) of tert-butyl-3-tert-butyl-L-tyrosinate as a white foam, m.p. 43-52° C.

Workup

  1. customTo a 250 mL round bottomed flask equipped with a magnetic stirrer
  2. customThe flask was sealed with a rubber septum
  3. customThe mixture was subjected to rotary evaporation
  4. customto remove isobutylene
  5. customAn emulsion resulted which
  6. extractionwas extracted with EtOAc (4×40 mL)
  7. washThe combined extracts were washed with 5% aqueous NaHCO3 (3×50 mL)
  8. dry with materialdried over anhydrous MgSO4
  9. concentrationconcentrated
  10. customto give a light yellow foam
  11. customThe Rf =0.45 product was isolated by flash chromatography on silica gel (95:5 CH2Cl2 :MeOH)

Sources & evidence

ORD record
ord-52cc611fd8b74904b55afc14380b570d
Source dataset
uspto-grants-2000_10
Patent number
US06140100

Reaction notes

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