Ammonium Chloride → 2-Ethenylbicyclo[4.2.0]octa-1,3,5-triene

HRID 1502557Notes

Reaction equation

HRID 1502557 reaction equation
[Li][CH2:2][CH2:3][CH2:4][CH3:5].C1[C:11]2[CH:12]=[CH:13][C:10]=2[CH:9]=[C:8](C=O)C=1.[NH4+].[Cl-].C([O-])(O)=O.[Na+]>[Br-].C[P+](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1.C1COCC1>[CH:4]([C:3]1[CH:2]=[CH:8][CH:9]=[C:10]2[CH2:13][CH2:12][C:11]=12)=[CH2:5]

Participants

7

Reactant 4

HCID 25517Ammonium ChlorideHCID 516892Sodium BicarbonateHCID 19963859Bicyclo[4.2.0]octa-1(6),2,4,7-tetraene-3-carbaldehydeHCID 178418339Butyllithium

Product 1

HCID 713412822-Ethenylbicyclo[4.2.0]octa-1,3,5-trieneYield 78%

Reagents, catalysts & solvents 2

HCID 74505Methyltriphenyliphosphonium bromideCatalystHCID 8028TetrahydrofuranSolvent2×

Procedure

To a 500 mL round bottom neck flask was added methyltriphenylphosphonium bromide 1.1 (48.6 g, 136.2 mmol), 220 mL of anhydrous THF, and the solution was cooled to −78 C. n-BuLi (2.5 M in hexane, 52.8 mL, 132 mmol) was added dropwise, and the reaction mixture was allowed to warm to room temperature. The yellow-orange solution was cooled to −78 C, and the aldehyde 1.2 (14.32 g, 108.4 mmol), diluted in anhydrous THF (70 mL) added slowly. The mixture was warmed to room temperature and stirring continued for 2 h. The reaction was treated sequentially with saturated NH4Cl and saturated NaHCO3 solution and the crude product was filtered over Celite, washed with diethyl ether/hexane (1:1), and evaporated to dryness (no heat) to give the crude product. Further purification by column chromatography using 5% diethyl ether/hexane as eluting solvents followed by vacuum distillation (75 C, 1.0 mm) gave the pure 4-Vinylbenzocyclobutene 1.3 as a colorless liquid (11 g, 78%). 1H NMR (300 MHz, CDCl3): δ 7.26 (d, 1H), 7.20 (s, 1H), 7.04 (d, 1H), 6.74 (dd, 1H), 5.70 (d, 1H), 5.20 (d, 1H), 3.19 (s, 4H).

Workup

  1. temperaturethe solution was cooled to −78 C
  2. temperatureThe yellow-orange solution was cooled to −78 C
  3. additionadded slowly
  4. temperatureThe mixture was warmed to room temperature
  5. filtrationthe crude product was filtered over Celite
  6. washwashed with diethyl ether/hexane (1:1)
  7. customevaporated to dryness (
  8. temperatureno heat)
  9. customto give the crude product
  10. customFurther purification by column chromatography
  11. washas eluting solvents
  12. distillationfollowed by vacuum distillation (75 C, 1.0 mm)

Sources & evidence

ORD record
ord-c9587dcd54714891a5d65bf99976f0ff
Source dataset
uspto-grants-2015_12
Patent number
US09209067B2

Reaction notes

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