(S)-3-Hydroxymethyl-N-(pyrid-3-yl)-1,2,3,4-tetrahydroisoquinoline-2-carbothioamide → 1,5,10,10a-Tetrahydrothiazolo[3,4-b]isoquinoline

(S)-3-Hydroxymethyl-N-(pyrid-3-yl)-1,2,3,4-tetrahydroisoquinoline-2-carbothioamide (13.5 g.) in 6N hydrochloric acid (300 cc.) is heated for 40 minutes at 100° C. After cooling, the solution obtained is concentrated under reduced pressure (25 mm. Hg) to 1/5 of its volume. It is rendered alkaline by adding 10N sodium hydroxide solution (200 cc.) and is then extracted with methylene chloride (3 × 150 cc.). The organic extracts are combined and then dried over magnesium sulphate. After filtering, and concentrating the filtrate to dryness under reduced pressure (25 mm. Hg), a yellow oil (11 g.) is obtained, which crystallises on addition of diisopropyl ether (150 cc.). The white crystals are filtered off, washed with diisopropyl ether (3 × 10 cc.) and then dried at 60° C., under reduced pressure (1 mm. Hg). (S)-3-Pyrid-3-ylimino)-1,5,10,10a-tetrahydrothiazolo[3,4-b]isoquinoline (9.8 g.), melting at 111° C., is thus obtained.

1. temperatureAfter cooling
2. customthe solution obtained
3. concentrationis concentrated under reduced pressure (25 mm. Hg) to 1/5 of its volume
4. additionby adding 10N sodium hydroxide solution (200 cc.)
5. extractionis then extracted with methylene chloride (3 × 150 cc.)
6. dry with materialdried over magnesium sulphate
7. filtrationAfter filtering
8. concentrationconcentrating the filtrate to dryness under reduced pressure (25 mm. Hg)
9. customa yellow oil (11 g.) is obtained
10. customwhich crystallises on addition of diisopropyl ether (150 cc.)
11. filtrationThe white crystals are filtered off
12. washwashed with diisopropyl ether (3 × 10 cc.)
13. customdried at 60° C., under reduced pressure (1 mm. Hg)

ORD record

ord-4688f5e753f2486781af3fafee378391

Source dataset

uspto-grants-1977_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04064247