Trifluoroacetic acid → Trifluoroacetate

Participants

Reaction Steps

1 g. (3 mMol) (±)-6-Hydroxy-7-methoxy-4-(3-hydroxy-4-methoxybenzyl)-2-methyl-1,2,3,4-tetrahydroisoquinoline is dissolved, with ice cooling, in 25 ml. trifluoroacetic acid and mixed at -10° C. with a solution of 0.42 ml. (0.77 g., 4.5 mMol) vanadium oxytrichloride in 5 ml. anhydrous methylene chloride within the course of 1 minute. The reaction mixture is allowed to react for 3 hours at -10° C., then concentrated in a vacuum to about one third of its volume and the concentrate partitioned between methylene chloride and water. Usual work up and crystallisation from acetone/diethyl ether gives (±)-5,6,6a,7-Tetrahydro-1,9-dihydroxy-2,10-dimethoxy-5-methyl-4H-dibenz(de,g)isoquinoline in the form of its trifluoroacetate; m.p. 208°-215° C.; yield 60-70% of theory. Hydrochloride: m.p. >300° C. (decomp.), after recrystallisation from methanol/chloroform.

Provenance & Evidence