Dichloromethane → 3-Bromo-6-methoxychroman-4-one

HRID 610390Notes

Reaction equation

HRID 610390 reaction equation
[CH3:1][O:2][C:3]1[CH:4]=[C:5]2[C:10](=[CH:11][CH:12]=1)[O:9][CH2:8][CH2:7][C:6]2=[O:13].[Br:14]Br.C(Cl)Cl>C(OCC)C>[Br:14][CH:7]1[C:6](=[O:13])[C:5]2[C:10](=[CH:11][CH:12]=[C:3]([O:2][CH3:1])[CH:4]=2)[O:9][CH2:8]1

Participants

5

Reactant 3

HCID 6344DichloromethaneHCID 24408BromineHCID 46121686-methoxy-3,4-dihydro-2H-1-benzopyran-4-one

Product 1

HCID 123873073-Bromo-6-methoxychroman-4-oneYield 80%

Reagents, catalysts & solvents 1

HCID 3283Diethyl EtherSolvent

Conditions

Temperature
7.5 °C

Procedure

To a solution of 6-methoxy-4-chromanone (35 g) in ethyl ether (1.6 liters) at 5-101 C. was added dropwise over 30 minutes 10.6 ml of bromine. The mixture was stirred at 5-10° C. for 30 minutes and then allowed to warm to room temperature. After 2 hours tlc (CH2Cl2) indicated formation of less polar products and only a trace of starting material remaining. The reaction mixture was washed with water (1 liter), saturated NaHCO3 (500 ml), and brine (500 ml). dried over MgSO4, and concentrated in vacuo to a yellow solid. The crude product was purified by silica gel flash column chromatography on 2.4 Kg fine silica gel, eluting with a gradient system consisting of 3:1 hexanes/dichloromethane followed by 2:1 hexanes/dichloromethane and finally 30% hexanes/dichloromethane. This afforded title product as a yellow solid in 80% yield.

Workup

  1. temperatureto warm to room temperature
  2. washThe reaction mixture was washed with water (1 liter), saturated NaHCO3 (500 ml), and brine (500 ml)
  3. dry with materialdried over MgSO4
  4. concentrationconcentrated in vacuo to a yellow solid
  5. customThe crude product was purified by silica gel flash column chromatography on 2.4 Kg fine silica gel
  6. washeluting with a gradient system

Sources & evidence

ORD record
ord-45c2c201f26f4183a90a6b5a0df03e85
Source dataset
uspto-grants-1999_12
Patent number
US05998451

Reaction notes

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