ChemicalBook CAS DataBase List 1-Bromobenzocyclobutene

1-Bromobenzocyclobutene synthesis

7synthesis methods

Product Name:1-Bromobenzocyclobutene
CAS Number:21120-91-2
Molecular formula:C8H7Br
Molecular Weight:183.05

75-25-2

544-25-2

21120-91-2

In a 250 mL round bottom flask equipped with a drying tube and condenser, cycloheptatriene (30.7 g, 300 mmol), tribromomethane (25.3 g, 100 mmol), anhydrous K2CO3 (15.0 g, 109 mmol), and 18-crown-6 (0.75 g) were added. The mixture was heated with stirring at 145°C for 9-10 hours. After completion of the reaction, the solution was allowed to cool to room temperature and diluted with an equal volume of acetone. Silica gel (15.0 g) was added to the reaction mixture and the insoluble solid residue was separated by vacuum filtration and the filter cake was washed with acetone until the washings were colorless. The filtrate was concentrated and the residual cycloheptatriene was removed by distillation. The viscous brown residue was dissolved in hot petroleum ether and the filtrate was concentrated after removing the precipitate by filtration. Vacuum distillation through a Vigreaux column gave slightly impure 1-bromobenzocyclobutene. Further purification by redistillation gave pure 1-bromobenzocyclobutene (2.95 g, 5.94% yield) as a light yellow liquid.1H NMR (300 MHz, CDCl3) δ 7.28 (m, 1H, ArH), 7.16 (d, 1H, J = 7.0 Hz, ArH), 7.07 (d, 1H, J = 6.4 Hz, ArH), 7.07 (d, 1H, J = 6.4 Hz, ArH) 5.39 (m, 1H, CH), 3.85 (dd, 1H, J = 4.4 Hz, J = 14.7 Hz, CH2), 3.45 (d, 1H, J = 14.7 Hz, CH2).

75-25-2 Synthesis

75-25-2
339 suppliers
$16.00/50g

544-25-2 Synthesis

544-25-2
115 suppliers
$10.00/5g

21120-91-2
91 suppliers
$30.00/100mg

Yield: 5.94%

Reaction Conditions:

with 18-crown-6 ether;potassium carbonate at 145; for 9 - 10 h;

Steps:

45
In a 250 mL round bottomed flask equipped with a drying tube and a condenser, a solution of cycloheptatriene (30.7 g, 300 mmol), bromoform (25.3 g, 100 mmol), anhydrous K2CO₃ (15.0 g, 109 mmol), and 18-crown-6 (0.75 g) was heated with stirring at 145 C for 9-10 h. The solution was allowed to cool and diluted with an equal15 volume of acetone. Silica gel (15.0 g) was added to reaction mixture and the insoluble solid residue was separated via vacuum filtration and the filter cake washed with acetone until the washings were colorless. The filtrate was concentrated and distilled to remove residual cycloheptatriene. The viscous, brown residue was precipitated into hot petroleum ether. After filtration to remove the precipitate, the filtrate was concentrated and distilled in vacuo20 through a Vigreaux column to give slightly impure product. Pure 1 -bromobenzocyclobutene was obtained as a light yellow liquid by redistillation yield (2.95 g, 5.94 %). ¹H NMR (300 MHz, CDCl₃) δ 7.28 (m, IH, ArH), 7.16 (d, IH, J=7.0Hz, ArH), 7.07 (d, IH, J=6.4Hz, ArH), 5.39 (m, IH, CH), 3.85 (dd, IH, J=4.4Hz, J=14.7Hz, CH₂), 3.45 (d, IH, J=14.7Hz, CH₂).

References:

VANDERBILT UNIVERSITY WO2008/24435, 2008, A2 Location in patent:Page/Page column 104