Acetone → 6-bromo-2,2-dimethyl-3,4-dihydro-2H-1-benzopyran-4-one

HRID 2096486Notes

Reaction equation

HRID 2096486 reaction equation
[Br:1][C:2]1[CH:3]=[CH:4][C:5]([OH:11])=[C:6]([C:8](=[O:10])[CH3:9])[CH:7]=1.[CH3:12][C:13]([CH3:15])=O.N1CCCC1.Cl>C1(C)C=CC=CC=1>[Br:1][C:2]1[CH:7]=[C:6]2[C:5](=[CH:4][CH:3]=1)[O:11][C:13]([CH3:15])([CH3:12])[CH2:9][C:8]2=[O:10]

Participants

6

Reactant 4

HCID 180Acetone2×HCID 313Hydrochloric AcidHCID 31268PyrrolidineHCID 959915'-Bromo-2'-hydroxyacetophenone

Product 1

HCID 147553646-bromo-2,2-dimethyl-3,4-dihydro-2H-1-benzopyran-4-oneYield 71%

Reagents, catalysts & solvents 1

HCID 1140TolueneSolvent

Procedure

A solution of 1-(5-bromo-2-hydroxyphenyl)-ethanone (21.4 g, 0.1 mol), acetone (365 mL) and pyrrolidine (8.4 mL) in toluene (220 mL) was refluxed for 4 h. To the reaction mixture was added acetone (36.5 mL). The mixture was refluxed for 15 h. Then 1 N HCl (220 mL) was added, and the resulting mixture was extracted with ethyl acetate (200 mL, 3×). The combined organic layers were washed with water (150 mL), brine (150 mL), dried over anhydrous Na2SO4, filtered, and evaporated to give 6-bromo-2,2-dimethyl-chroman-4-one (18.0 g, 71%). 1H-NMR (CDCl3): 1.45 (s, 6 H), 2.71 (s, 2 H), 6.82 (d, 1 H), 7.52 (dd, 1 H), 7.96 (d, 1 H).

Workup

  1. temperatureThe mixture was refluxed for 15 h
  2. extractionthe resulting mixture was extracted with ethyl acetate (200 mL, 3×)
  3. washThe combined organic layers were washed with water (150 mL), brine (150 mL)
  4. dry with materialdried over anhydrous Na2SO4
  5. filtrationfiltered
  6. customevaporated

Sources & evidence

ORD record
ord-1346a5ab2a8648fa8332aa8604927f44
Source dataset
uspto-grants-2013_05
Patent number
US08450308B2

Reaction notes

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