Reaktion #527663

Reaktionsgleichung

sodium cyanoborohydride

(-)-1-[1-(2-bromophenyl)cyclobutyl]-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline

dibenzoyl-(L)-tartrate

formaldehyde

→

(-)-1-[1-(2-bromophenyl)cyclobutyl]-6,7-dimethoxy-2-methyl-1,2,3,4-tetrahydroisoquinoline

Lösungsmittel

acetonitrile

acetic acid

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGstirred for a further 45 minutes
2. 2
   EinengenThe mixture was concentrated by evaporation
3. 3
   ExtraktionThe mixture was extracted with ethyl acetate
4. 4
   Sonstigethe extract yielding a gum which
5. 5
   Sonstigewas purified via flash chromatography
6. 6
   workup.ADDITIONa 1:2 mixture of ethyl acetate and petroleum ether as eluant

Vorschrift

A mixture of (-)-1-[1-(2-bromophenyl)cyclobutyl]-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline (1.85 g) [liberated from the dibenzoyl-(L)-tartrate salt (3.7 g)], acetonitrile (60 ml), 37-40% aqueous formaldehyde solution (1.8 ml) and sodium cyanoborohydride (0.46 g) was stirred for 15 minutes, then neutralised with glacial acetic acid and stirred for a further 45 minutes. The mixture was concentrated by evaporation and basified to pH 12 with dilute aqueous sodium hydroxide solution. The mixture was extracted with ethyl acetate, the extract yielding a gum which was purified via flash chromatography using a 1:2 mixture of ethyl acetate and petroleum ether as eluant to give (-)-1-[1-(2-bromophenyl)cyclobutyl]-6,7-dimethoxy-2-methyl-1,2,3,4-tetrahydroisoquinoline, which had a specific optical rotation αD of -33.6°. Yield 1.6 g.

Quelle