Phosphorus oxide (P4O10) → 3,4-Dihydroisoquinoline

HRID 398740

Reaction equation

HRID 398740 reaction equation
O=P12OP3(OP(OP(O3)(O1)=O)(=O)O2)=O.[CH2:15]([NH:23][CH:24]=O)[CH2:16][C:17]1[CH:22]=[CH:21][CH:20]=[CH:19][CH:18]=1>O>[CH:24]1[C:22]2[C:17](=[CH:18][CH:19]=[CH:20][CH:21]=2)[CH2:16][CH2:15][N:23]=1

Participants

4

Reactant 2

HCID 14812Phosphorus oxide (P4O10)HCID 140995Formamide, N-(2-phenylethyl)-

Product 1

HCID 767053,4-Dihydroisoquinoline

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Conditions

Temperature
180 °C

Procedure

A 250 mL round bottom flask equipped with stir bar, reflux condenser, and an addition funnel is charged with phosphorus pentoxide (7.07 g) and polyphosphoric acid in a 10.5:1 weight ratio. The mixture is stirred and heated at approximately 180° C. for about 1 hour, then cooled to approximately 150° C. The cooled, crude phenethylformamide prepared as described above is added dropwise to this mixture. On complete addition the reaction is heated and stirred at approximately 170° C. overnight. The mixture is cooled to room temperature and diluted with water (300 mL), washed with diethyl ether (150 mL) and cooled in an acetone/dry ice bath while the pH is adjusted to 9 with saturated potassium hydroxide. The aqueous solution is extracted with ether (3×150 mL) and the pooled organics are dried over magnesium sulfate, filtered, and concentrated under reduced pressure to yield an oil that is further purified via Kugelrohr distillation (70° C., 1 mm Hg) to give the compound of formula 2.

Workup

  1. customA 250 mL round bottom flask equipped
  2. temperaturereflux condenser, and an addition funnel
  3. stirringThe mixture is stirred
  4. temperaturecooled to approximately 150° C
  5. additionabove is added dropwise to this mixture
  6. additionOn complete addition the reaction
  7. temperatureis heated
  8. stirringstirred at approximately 170° C. overnight
  9. temperatureThe mixture is cooled to room temperature
  10. washwashed with diethyl ether (150 mL)
  11. temperaturecooled in an acetone/dry ice bath while the pH
  12. extractionThe aqueous solution is extracted with ether (3×150 mL)
  13. dry with materialthe pooled organics are dried over magnesium sulfate
  14. filtrationfiltered
  15. concentrationconcentrated under reduced pressure
  16. customto yield an oil that
  17. distillationis further purified via Kugelrohr distillation (70° C., 1 mm Hg)

Sources & evidence

ORD record
ord-af0bf58df29f4d24baf33cff16d27aac
Source dataset
uspto-grants-1998_10
Patent number
US05817614

Linked notes

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