Reaktion #632832

Reaktionsgleichung

cycloheptatriene

bromoform

K2CO3

18-crown-6

→

1-bromobenzocyclobutene

Lösungsmittel

acetone

Reaktionsbedingungen

Aufarbeitung

1. 1
   SonstigeIn a 250 mL round bottomed flask equipped with a drying tube and a condenser
2. 2
   Temperaturto cool
3. 3
   workup.ADDITIONSilica gel (15.0 g) was added to reaction mixture
4. 4
   Sonstigethe insoluble solid residue was separated via vacuum filtration
5. 5
   Waschenthe filter cake washed with acetone until the washings
6. 6
   EinengenThe filtrate was concentrated
7. 7
   workup.DISTILLATIONdistilled
8. 8
   Sonstigeto remove residual cycloheptatriene
9. 9
   SonstigeThe viscous, brown residue was precipitated into hot petroleum ether
10. 10
    FiltrationAfter filtration
11. 11
    Sonstigeto remove the precipitate
12. 12
    Einengenthe filtrate was concentrated
13. 13
    workup.DISTILLATIONdistilled in vacuo through a Vigreaux column
14. 14
    Sonstigeto give slightly impure product

Vorschrift

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 equal 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 vacuo 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, 1H, ArH), 7.16 (d, 1H, J=7.0 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).

Quelle