Boron trifluoride etherate → 2,3,4,5-Tetrahydro-1-benzoxepin-4-one

HRID 1949876Notes

Reaction equation

HRID 1949876 reaction equation
[O:1]1[C:10]2[C:5](=[CH:6][CH:7]=[CH:8][CH:9]=2)[C:4](=[O:11])[CH2:3][CH2:2]1.B(F)(F)F.[CH3:16]COCC.[Si](C=[N+]=[N-])(C)(C)C.C([O-])(O)=O.[Na+]>C(OCC)C>[O:1]1[CH2:2][CH2:3][C:4](=[O:11])[CH2:16][C:5]2[CH:6]=[CH:7][CH:8]=[CH:9][C:10]1=2

Participants

6

Reactant 4

HCID 8000Boron trifluoride etherateHCID 68110ChromanoneHCID 167693TrimethylsilyldiazomethaneHCID 516892Sodium Bicarbonate

Product 1

HCID 125800312,3,4,5-Tetrahydro-1-benzoxepin-4-oneYield 42.2%

Reagents, catalysts & solvents 1

HCID 3283Diethyl EtherSolvent2×

Conditions

Temperature
0 °C

Procedure

To a solution of 4-chromanone (1 eq, 16.8 mmol, 2.5 g) in anhydrous diethyl ether (70 ml) at 0° C., boron trifluoride diethyl etherate (1.1 eq, 18.6 mmol, 2.4 ml) was added dropwise followed by the dropwise addition of 2M TMS diazomethane in ether (1.1 eq, 18.6 mmol, 9.2 ml), and stirred at 0° C. under N2 for 1 hr. Saturated NaHCO3 aq was carefully added (100 ml) and the reaction extracted into diethyl ether, the organic layer was then washed with water before drying over MgSO4, filtering and absorbing onto silica. The crude material was then purified on the ISCO companion system running a gradient from 0% ethyl acetate/petrol to 20% ethyl acetate/petrol. This gave 2,3-dihydro-5H-benzo[b]oxepin-4-one as a yellow oil (1.15 g, yield 42%).

Workup

  1. extractionthe reaction extracted into diethyl ether
  2. washthe organic layer was then washed with water
  3. dry with materialbefore drying over MgSO4
  4. filtrationfiltering
  5. customabsorbing onto silica
  6. customThe crude material was then purified on the ISCO companion system

Sources & evidence

ORD record
ord-701b2247eae04a1e8acb8f35276c0994
Source dataset
uspto-grants-2013_03
Patent number
US08399690B2

Reaction notes

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