Boron trifluoride etherate → (+)-4,5,6,7-Tetrahydro-6-[2-[4-(2-pyridinyl)-1-piperazinyl]ethyl]-2-benzothiazolamine

HRID 704582Notes

Reaction equation

HRID 704582 reaction equation
[NH2:1][C:2]1[S:3][C:4]2[CH2:10][CH:9]([CH2:11][C:12]([N:14]3[CH2:19][CH2:18][N:17]([C:20]4[CH:25]=[CH:24][CH:23]=[CH:22][N:21]=4)[CH2:16][CH2:15]3)=O)[CH2:8][CH2:7][C:5]=2[N:6]=1.[BH4-].[Na+].B(F)(F)F.CCOCC>O1CCCC1>[N:21]1[CH:22]=[CH:23][CH:24]=[CH:25][C:20]=1[N:17]1[CH2:18][CH2:19][N:14]([CH2:12][CH2:11][CH:9]2[CH2:8][CH2:7][C:5]3[N:6]=[C:2]([NH2:1])[S:3][C:4]=3[CH2:10]2)[CH2:15][CH2:16]1

Participants

5

Reactant 3

HCID 8000Boron trifluoride etherateHCID 4311764Sodium borohydrideHCID 20072906(+)-1-[(2-Amino-4,5,6,7-tetrahydro-6-benzothiazolyl)acetyl]-4-(2-pyridyl)piperazine

Product 1

HCID 9884515(+)-4,5,6,7-Tetrahydro-6-[2-[4-(2-pyridinyl)-1-piperazinyl]ethyl]-2-benzothiazolamineYield 67.1%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Procedure

To a solution of (+)-1-[(2-amino-4,5,6,7-tetrahydro-6-benzothiazolyl)acetyl]-4-(2-pyridyl)piperazine (2.70 g) (Example M) in 250 ml of tetrahydrofuran is added sodium borohydride (1.07 g) under nitrogen. This suspension is cooled in an ice bath and boron trifluoride etherate (4.6 ml) added dropwise. The mixture is stirred at room temperature for one hour and the solvent removed in vacuo. The residue is dissolved in 250 ml of a 10% solution of hydrochloric acid and stirred for two hours. The solution is made basic with ammonium hydroxide and extracted with chloroform (2×200 ml). The combined chloroform extracts are dried (magnesium sulfate), filtered, and concentrated. The residue is purified by MPLC (silica; 5% methanol, 95% chloroform) to give 1.74 g of (+)-4,5,6,7-tetrahydro-6-[2-[4-(2-pyridinyl)-1-piperazinyl]ethyl]-2-benzothiazolamine, containing one-fourth of a molecule of water, as a colorless solid; mp 176°-190° C.; [α]D =+52.2° (c=1.02; 0.1 N hydrochloric acid solution).

Workup

  1. temperatureThis suspension is cooled in an ice bath
  2. customthe solvent removed in vacuo
  3. dissolutionThe residue is dissolved in 250 ml of a 10% solution of hydrochloric acid
  4. stirringstirred for two hours
  5. extractionextracted with chloroform (2×200 ml)
  6. dry with materialThe combined chloroform extracts are dried (magnesium sulfate)
  7. filtrationfiltered
  8. concentrationconcentrated
  9. customThe residue is purified by MPLC (silica; 5% methanol, 95% chloroform)

Sources & evidence

ORD record
ord-e56a844cbdc043b8a6f906c0846e05ab
Source dataset
uspto-grants-1991_01
Patent number
US04988699

Reaction notes

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