Reaction #577219

Reaction equation

3-Bromo-1-propene

7-hydroxy-4-methylcoumarin

potassium carbonate

→

2

Yield 96.2%

7-Allyloxy-4-methylcoumarin

Yield 96.2%

Solvents

acetone

Conditions

Workup

1. 1
   TemperatureThe resulting mixture was then refluxed for 4 h
2. 2
   Temperatureto cool
3. 3
   Filtrationthe K2CO3 filtered off
4. 4
   Washwashed with fresh acetone
5. 5
   OtherThe solvent was removed in vacuo
6. 6
   Otherthe residue was crystallized from methanol

Procedure

3-Bromo-1-propene (2.95 mL, 34.06 mmol) was added dropwise under argon to a stirred mixture of 7-hydroxy-4-methylcoumarin 1 (2.0 g, 11.35 mmol) and anhydrous potassium carbonate (K2CO3) (2.35 g, 17.03 mmol) in acetone (50 mL). The resulting mixture was then refluxed for 4 h, after which it was allowed to cool, and the K2CO3 filtered off and washed with fresh acetone. The solvent was removed in vacuo and the residue was crystallized from methanol to afford 2 as white-cream crystals (2.36 g, 96%). TLC (hexane/ethyl acetate, 1:3): Rf=0.63. mp 110° C. 1H NMR (CDCl3, 500 MHz) δ 2.39 (s, 3H, CH3), 4.60 (d, J=5.0 Hz, 2H, CH2), 5.33 (d, J=10.5 Hz, 1H), 5.44 (d, J=17.5 Hz, 1H), 6.05 (m, 1H), 6.12 (s, 1H), 6.80 (s, 1H), 6.87 (dd, J=1.5, 9.0 Hz, 1H), 7.49 (d, J=9.0 Hz, 1H). 13C NMR (CDCl3, 125 MHz) δ 18.70, 69.29, 101.84, 112.05, 112.79, 113.75, 118.51, 125.64, 132.31, 152.61, 152.26, 161.26, 161.65. ESIMS calcd for C13H13O3 [M+H]+ 217.1, found 217.1.

Source