Reaktion #1678028

Reaktionsgleichung

(R)-(-)-N-acetyl-7,8-dimethoxy-4-(3,4-dimethoxyphenyl)-1,2,3,4-tetrahydroisoquinoline

boron tribromide dichloromethane

methanol

→

(R)-(-)-N-acetyl-7,8-dihydroxy-4-(3,4-dihyroxyphenyl)-1,2,3,4-tetrahydroisoquinoline

Ausbeute 96.6%

Lösungsmittel

dichloromethane

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigethe mixture was reacted at room temperature for 90 minutes
2. 2
   EinengenThe reaction solution was concentrated
3. 3
   workup.DISTILLATIONsubjected twice to azeotropic distillation with methanol
4. 4
   workup.ADDITIONTo the residue was added 17.8 ml of 0.1N hydrochloric acid
5. 5
   SonstigeThe crystals which separated out
6. 6
   Filtrationwere collected by filtration

Vorschrift

(i)1.78 g of (R)-(-)-N-acetyl-7,8-dimethoxy-4-(3,4-dimethoxyphenyl)-1,2,3,4-tetrahydroisoquinoline was dissolved in 9 ml of dichloromethane; after adding 24 ml of 1M boron tribromide-dichloromethane solution at -30 ° C., the mixture was reacted at room temperature for 90 minutes. Then 4.4 ml of methanol was added at -30° C. The reaction solution was concentrated and subjected twice to azeotropic distillation with methanol. To the residue was added 17.8 ml of 0.1N hydrochloric acid. The crystals which separated out were collected by filtration, affording 1.46 g of (R)-(-)-N-acetyl-7,8-dihydroxy-4-(3,4-dihyroxyphenyl)-1,2,3,4-tetrahydroisoquinoline.1/4 hydrate, m.p. above 230° C. (decomposition): [α]D20 =-85° (C=1, CH3OH)

Quelle