3-Cyanopyridine → 3-(3,5-Dibromobenzoyl)pyridine

HRID 725026Notes

Reaction equation

HRID 725026 reaction equation
C([Li])CCC.Br[C:7]1[CH:12]=[C:11]([Br:13])[CH:10]=[C:9]([Br:14])[CH:8]=1.[C:15]([C:17]1[CH:18]=[N:19][CH:20]=[CH:21][CH:22]=1)#N.Cl.CC[O:26]CC>CCCCCC>[Br:14][C:9]1[CH:8]=[C:7]([CH:12]=[C:11]([Br:13])[CH:10]=1)[C:15]([C:17]1[CH:18]=[N:19][CH:20]=[CH:21][CH:22]=1)=[O:26]

Participants

7

Reactant 5

HCID 793-CyanopyridineHCID 313Hydrochloric AcidHCID 3283Diethyl Ether2×HCID 122791,3,5-TribromobenzeneHCID 178418339Butyllithium

Product 1

HCID 106649193-(3,5-Dibromobenzoyl)pyridine

Reagents, catalysts & solvents 1

HCID 8058HexaneSolvent

Conditions

Temperature
-78 °C

Procedure

A 2.5M solution of n-butyllithium in hexane (40.0 ml) was added dropwise to a stirred mixture of 1,3,5-tribromobenzene (31.5 g) and dry ether (1000 ml) at -78° C. under an atmosphere of dry nitrogen. The resulting solution was stirred at -78° C. for 30 minutes and then a solution of 3-cyanopyridine (10.4 g) in dry ether (100 ml) was added dropwise. The mixture was stirred at -78° C. for 1 hour and then the temperature was allowed to reach 0° C. 2N Hydrochloric acid (200 ml) was added, with stirring, and the ether layer was decanted off and then extracted several times with 2N hydrochloric acid. The acidic extracts were combined and warmed on a steam bath for 20 minutes, then the solution was cooled and basified with aqueous potassium hydroxide solution. The resulting solid was filtered off, washed with water, dried and combined with the solid obtained by evaporation under vacuum of the ether solution. The crude product was chromatographed on silica gel using dichloromethane as eluent; the earlier fractions contained impurity and the later fractions were combined and evaporated under vacuum. The solid obtained from the latter fractions was crystallised from ethyl acetate-hexane to give the title compound (23.33 g), m.p. 124°-126° C. Found: C, 42.50; H, 2.23; N, 4.21. C12H7Br2NO requires C, 42.26; H, 2.07; N, 4.11%.

Workup

  1. stirringThe mixture was stirred at -78° C. for 1 hour
  2. customto reach 0° C
  3. stirringwith stirring
  4. customthe ether layer was decanted off
  5. extractionextracted several times with 2N hydrochloric acid
  6. temperaturewarmed on a steam bath for 20 minutes
  7. temperaturethe solution was cooled
  8. filtrationThe resulting solid was filtered off
  9. washwashed with water
  10. customdried
  11. customobtained by evaporation under vacuum of the ether solution
  12. customThe crude product was chromatographed on silica gel
  13. customevaporated under vacuum
  14. customThe solid obtained from the latter fractions
  15. customwas crystallised from ethyl acetate-hexane

Sources & evidence

ORD record
ord-7c750c52ad2845f582c08d041d9309a3
Source dataset
uspto-grants-1998_01
Patent number
US05705523

Reaction notes

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