Toluene → 6-Bromo-4,4-dimethyl-2-methylene chroman

HRID 2185244Notes

Reaction equation

HRID 2185244 reaction equation
[Br:1][C:2]1[CH:3]=[C:4]2[C:9](=[CH:10][CH:11]=1)[O:8][C:7](=O)[CH2:6][C:5]2([CH3:14])[CH3:13].[C:15]1(C)C=CC=CC=1>[CH3-].C[Al+]C.[CH-]1C=CC=C1.[CH-]1C=CC=C1.[Cl-].[Ti+3].[OH-].[Na+]>[Br:1][C:2]1[CH:3]=[C:4]2[C:9](=[CH:10][CH:11]=1)[O:8][C:7](=[CH2:15])[CH2:6][C:5]2([CH3:14])[CH3:13]

Participants

5

Reactant 2

HCID 1140TolueneHCID 225689232H-1-Benzopyran-2-one, 6-bromo-3,4-dihydro-4,4-dimethyl-

Product 1

HCID 187102226-Bromo-4,4-dimethyl-2-methylene chromanYield 74%

Reagents, catalysts & solvents 2

HCID 53384502mu-Chlorobis(eta5-cyclopentadienyl)(dimethylaluminum)-mu-methylenetitaniumCatalystHCID 14798Sodium HydroxideSolvent

Procedure

A stirred, cooled (ice bath) solution of 6-bromo-4,4-dimethyl-chroman-2-one available in accordance with U.S. Pat. No. 5,399,561 incorporated herein by reference (1 g, 3.92 mmol) in 8 mL of anhydrous tetrahydrofuiran was treated with a 0.5 M solution of μ-chloro-μ-methylene-[ bis(cyclopentadienyl)titanium]dimethylaluminum (Tebbe reagent) in toluene (8.23 mL, 4.12 mmol). After 10 minutes, the reaction mixture was poured into ice-water mixture containing 50 mL of 1M sodium hydroxide and extracted with hexane. The hexane extract was washed with brine (×1), filtered over a bed of celite and evaporated in vacuo to an oil which was subjected to flash column chromatography over silica gel (230-400 mesh) using hexane as the eluent to afford the title compound (0.74 g, 74%) as a clear oil. 1H NMR (300 MHz, CDCl3): δ 7.34 (d, 1H, J=2.3 Hz), 7.23 (dd, 1H, J=2.3, 8.5 Hz), 6.77 (d, 1H, J=8.0 Hz), 4.61 (d, 1H, J=0.73 Hz), 4.17 (d, 1H, J=0.73 Hz), 2.33 (s, 2H), 1.27 (s, 6H).

Workup

  1. extractionextracted with hexane
  2. extractionThe hexane extract
  3. washwas washed with brine (×1)
  4. filtrationfiltered over a bed of celite
  5. customevaporated in vacuo to an oil which

Sources & evidence

ORD record
ord-f5436c976a424a42a8ab5d19617228ae
Source dataset
uspto-grants-2002_06
Patent number
US06399774B1

Reaction notes

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