6-bromo-2,2-dimethyl-4H-spiro[chromene-3,3'-oxetan]-4-one → 6-bromo-2,2-dimethyl-4-methylene-4H-spiro[chromene-3,3'-oxetane]

HRID 873702Notes

Reaction equation

HRID 873702 reaction equation
[CH2:1]([Li])CCC.[Br:6][C:7]1[CH:8]=[C:9]2[C:17](=[CH:18][CH:19]=1)[O:16][C:15]([CH3:21])([CH3:20])[C:11]1([CH2:14][O:13][CH2:12]1)[C:10]2=O>[Br-].C[P+](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1.C1COCC1>[Br:6][C:7]1[CH:8]=[C:9]2[C:17](=[CH:18][CH:19]=1)[O:16][C:15]([CH3:21])([CH3:20])[C:11]1([CH2:14][O:13][CH2:12]1)[C:10]2=[CH2:1]

Participants

5

Reactant 2

HCID 867242436-bromo-2,2-dimethyl-4H-spiro[chromene-3,3'-oxetan]-4-oneHCID 178418339Butyllithium

Product 1

HCID 867242426-bromo-2,2-dimethyl-4-methylene-4H-spiro[chromene-3,3'-oxetane]Yield 92%

Reagents, catalysts & solvents 2

HCID 74505Methyltriphenyliphosphonium bromideCatalystHCID 8028TetrahydrofuranSolvent2×

Procedure

To a suspension of methyl(triphenyl)phosphonium bromide (8.13 g, 22.3 mmol) in THF (44 mL) was added n-butyllithium (1.65 M in n-hexane, 13.5 mL, 22.3 mmol) in a dry ice-acetone bath under argon atmosphere. The mixture was stirred for 60 minutes in an ice bath. To the mixture was added a mixture of 6-bromo-2,2-dimethyl-4H-spiro[chromene-3,3′-oxetan]-4-one (2.21 g, 7.44 mmol) and THF (11 mL) in an ice bath. The mixture was stirred for 1 hour at ambient temperature. The reaction was quenched by adding water in an ice-water bath. The mixture was partitioned between EtOAc-hexane (1:2) and water. The organic layer was washed with brine, dried over MgSO4, filtered, and the filtrate was evaporated. Purification using silica gel column chromatography (EtOAc-hexane, a linear gradient of EtOAc from 0 to 20%) afforded 6-bromo-2,2-dimethyl-4-methylene-4H-spiro[chromene-3,3′-oxetane] (2.02 g).

Workup

  1. additionTo the mixture was added
  2. stirringThe mixture was stirred for 1 hour at ambient temperature
  3. customThe reaction was quenched
  4. additionby adding water in an ice-water bath
  5. customThe mixture was partitioned between EtOAc-hexane (1:2) and water
  6. washThe organic layer was washed with brine
  7. dry with materialdried over MgSO4
  8. filtrationfiltered
  9. customthe filtrate was evaporated
  10. customPurification

Sources & evidence

ORD record
ord-bc95b8f70f4a456e9b7a4b1a15e9fdc9
Source dataset
uspto-grants-2015_03
Patent number
US08975415B2

Reaction notes

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