Ammonium Chloride → HCID 86751639, compound

HRID 2294699Notes

Reaction equation

HRID 2294699 reaction equation
[CH3:1][O:2][C:3]1[C@@H:4]([CH:11]([CH3:13])[CH3:12])[N:5]=[C:6]([O:9][CH3:10])[CH2:7][N:8]=1.C([Li])CCC.Br[CH2:20][C@H:21]1[CH2:26][CH2:25][CH:24]=[CH:23][CH2:22]1.[Cl-].[NH4+]>O1CCCC1.CCCCCC>[C@H:21]1([CH2:20][C@H:7]2[C:6]([O:9][CH3:10])=[N:5][C@H:4]([CH:11]([CH3:13])[CH3:12])[C:3]([O:2][CH3:1])=[N:8]2)[CH2:26][CH2:25][CH:24]=[CH:23][CH2:22]1

Participants

7

Reactant 4

HCID 25517Ammonium ChlorideHCID 736066(R)-2,5-Dihydro-3,6-dimethoxy-2-isopropylpyrazineHCID 54346043Cyclohexene, 4-(bromomethyl)-, (S)-HCID 178418339Butyllithium

Product 1

HCID 86751639HCID 86751639, compound

Reagents, catalysts & solvents 2

HCID 8028TetrahydrofuranSolvent2×HCID 8058HexaneSolvent

Procedure

A solution, cooled to -78°, of 1.78 ml (10 mmol) of (2R)-(-)-2,5-dihydro-3,6-dimethoxy-2-isopropylpyrazine in 5 ml of absolute tetrahydrofuran is treated dropwise with 6.8 ml (11 mmol) of a solution of butyllithium in hexane. The reaction solution is left at -78° for 1 hour and at -20° for 1 hour and then again cooled to -78°. Subsequently, a solution of 1.75 g (10 mmol) of (S)-1-(bromomethyl)-3-cyclohexene in 5 ml of absolute tetrahydrofuran is added. After 2 hours at room temperature the solution is again cooled to -10°, treated with 5 ml of saturated ammonium chloride solution and extracted with ether. The organic phase is washed with water, dried over sodium sulphate and evaporated under reduced pressure. For purification, the residue is chromatographed twice on silica gel using a 9:1 mixture of toluene and ethyl acetate as the eluent. (2S,5R)-2-[(S)-3-Cyclohexen-1-ylmethyl]-2,5-dihydro-5-isopropyl-3,6-dimethoxypyrazine is obtained as a colourless oil; MS: 278 (M)+.

Workup

  1. temperatureagain cooled to -78°
  2. extractionextracted with ether
  3. washThe organic phase is washed with water
  4. dry with materialdried over sodium sulphate
  5. customevaporated under reduced pressure
  6. customFor purification
  7. customthe residue is chromatographed twice on silica gel using
  8. additiona 9:1 mixture of toluene and ethyl acetate as the eluent

Sources & evidence

ORD record
ord-9ac10af988ab4bcb936444ddf54e0d2f
Source dataset
uspto-grants-1997_11
Patent number
US05688946

Reaction notes

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