(-)-Mandelic acid → (s)-(+)-3-(4-Fluorobenzyl)piperidine mandelic acid salt

HRID 497449Notes

Reaction equation

HRID 497449 reaction equation
[F:1][C:2]1[CH:14]=[CH:13][C:5]([CH2:6][CH:7]2[CH2:12][CH2:11][CH2:10][NH:9][CH2:8]2)=[CH:4][CH:3]=1.[C:15]([OH:25])(=[O:24])[C@@H:16]([C:18]1[CH:23]=[CH:22][CH:21]=[CH:20][CH:19]=1)[OH:17]>C(#N)C>[C:15]([OH:25])(=[O:24])[CH:16]([C:18]1[CH:23]=[CH:22][CH:21]=[CH:20][CH:19]=1)[OH:17].[F:1][C:2]1[CH:3]=[CH:4][C:5]([CH2:6][C@@H:7]2[CH2:12][CH2:11][CH2:10][NH:9][CH2:8]2)=[CH:13][CH:14]=1

Participants

4

Reactant 2

HCID 11914(-)-Mandelic acidHCID 34323433-(4-Fluorobenzyl)piperidine

Product 1

HCID 69358447(s)-(+)-3-(4-Fluorobenzyl)piperidine mandelic acid salt

Reagents, catalysts & solvents 1

HCID 6342AcetonitrileSolvent2×

Procedure

The crude racemic 3-(4-fluorobenzyl)piperidine (2.0 g) was dissolved in 25 mL acetonitrile and heated to reflux. The solution was hazy. To this was added 1.56 g (1 equiv.) of (R)-(−) mandelic acid dissolved in 15 mL acetonitrile. Some initial precipitation occurred when the cooler solution was added but it did redissolve when refluxing resumed. The heat was turned off and small amounts of enantiomerically pure salt was added as the temperature dropped. At first the seed crystals dissolved, but when the temperature dropped to 75° C., they remained suspended in the stirred solution. After a few more degrees of cooling, crystal growth was obvious. Cooling was continued at the rate of 1 degree/min. At 50° C., the solution was filtered to recover 0.9 g of salt, which melted at 164° C. It was recrystallized from acetonitrile twice to give (S)-(+)-3-(4-fluorobenzyl)piperidine mandelic acid salt in 98% ee, and melting at 168-171° C.

Workup

  1. temperatureheated to reflux
  2. customSome initial precipitation
  3. additionwas added
  4. dissolutionit did redissolve when
  5. temperaturerefluxing
  6. additionsmall amounts of enantiomerically pure salt was added as the temperature
  7. additiondropped
  8. dissolutionAt first the seed crystals dissolved
  9. additionwhen the temperature dropped to 75° C.
  10. temperatureAfter a few more degrees of cooling
  11. temperatureCooling
  12. filtrationAt 50° C., the solution was filtered
  13. customto recover 0.9 g of salt, which melted at 164° C
  14. customIt was recrystallized from acetonitrile twice

Sources & evidence

ORD record
ord-bb418970dadc4c989a7441cd9cca0ec4
Source dataset
uspto-grants-2005_09
Patent number
US06949546B2

Reaction notes

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