4-Aminopyridine → (10aS)-1,5,10,10a-Tetrahydro-3H-[1,3]thiazolo[3,4-b]isoquinoline-3-thione

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Reaction Steps

(S)-3-Methylthio-1,5,10,10a-tetrahydrothiazolo[3,4-b]isoquinolinium iodide (14.5 g.) is added, a little at a time, to a solution of 4-aminopyridine (7.5 g.) in pyridine (300 cc.). The suspension gradually passes into solution. After 24 hours at a temperature of about 20° C., the suspension is concentrated to dryness under reduced pressure (25 mm. Hg). The residue is dissolved in a mixture of methylene chloride (250 cc.) and water (200 cc.). The organic phase is decanted, dried over magnesium sulphate, filtered and then concentrated to about 100 cc. under reduced pressure. This solution is poured onto a column (column diameter: 3 cm) of silica gel (300 g.) and elution is then carried out with a 1% v/v solution of methanol in methylene chloride, eluate fractions of 500 cc. being collected. After evaporating fractions 2 and 3 to dryness, (S)-1,5,10,10a-tetrahydrothiazolo[3,4-b]isoquinoline-3-thione (2.0 g.) is obtained.

Provenance & Evidence