Triethylamine → Ethyl 2-(cyclopropylethynyl)oxazole-4-carboxylate

HRID 1526606Notes

Reaction equation

HRID 1526606 reaction equation
[CH2:1]([O:3][C:4]([C:6]1[N:7]=[C:8](Br)[O:9][CH:10]=1)=[O:5])[CH3:2].[C:12]([CH:14]1[CH2:16][CH2:15]1)#[CH:13].C(N(CC)CC)C>C1(C)C=CC=CC=1.Cl[Pd](Cl)([P](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1)[P](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1.[Cu]I>[CH:14]1([C:12]#[C:13][C:8]2[O:9][CH:10]=[C:6]([C:4]([O:3][CH2:1][CH3:2])=[O:5])[N:7]=2)[CH2:16][CH2:15]1

Participants

7

Reactant 3

HCID 8471TriethylamineHCID 138823CyclopropylacetyleneHCID 26370035Ethyl 2-bromo-1,3-oxazole-4-carboxylate

Product 1

HCID 90389314Ethyl 2-(cyclopropylethynyl)oxazole-4-carboxylateYield 50.1%

Reagents, catalysts & solvents 3

HCID 24350Copper(1+) iodide; Copper(I) iodide; Cuprous iodide; Cuprous iodide (CuI)CatalystHCID 178418476HCID 178418476, compoundCatalystHCID 1140TolueneSolvent

Procedure

A mixture of 2-bromo-oxazol-4-carboxylic ethyl ester (0.967 g, 4.40 mmol, Combi-Blocks), trans-dichlorobis(triphenylphosphine)palladium (II) (0.201 g, 0.286 mmol, Strem) and copper (I) iodide (0.165 g, 0.866 mmol, Aldrich) in toluene (15 ml) was purged with argon for 10 min. Ethynylcyclopropane (1.00 ml, 11.80 mmol) and triethylamine (1.70 ml, 12.22 mmol) were added. After 2.5 h, the reaction mixture was partitioned between CH2Cl2 and water. The aqueous layer was extracted with CH2Cl2 (3×). The combined organic layers were washed with brine. The solvent was removed under reduced pressure and the residue and was purified by silica gel flash chromatography, eluting with (EtOAc):hexanes (0:1→2:3) to give 452 mg (50%) of a light-orange oil. MS m/z=206 [M+H]+. Calculated for C11H11NO3: 205.

Workup

  1. customwas purged with argon for 10 min
  2. customthe reaction mixture was partitioned between CH2Cl2 and water
  3. extractionThe aqueous layer was extracted with CH2Cl2 (3×)
  4. washThe combined organic layers were washed with brine
  5. customThe solvent was removed under reduced pressure
  6. customthe residue and was purified by silica gel flash chromatography
  7. washeluting with (EtOAc)

Sources & evidence

ORD record
ord-cb9881188c9f4019927af742f2342fc3
Source dataset
uspto-grants-2015_07
Patent number
US09085576B2

Reaction notes

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