Acetylene derivatives Communication 152. Heterocyclic compounds. XXVIII. The synthesis of some derivatives of tetrahydro-γ-thiopyrones

Summary

• 1. By the interaction of 2,5-dimethyltetrahydro-1-thiopyran-4-one (I) and its corresponding ,sulfone (II) with hydroxylamine hydrochloride in alcoholic solution, the corresponding oximes (III) and (IV) were obtained.

• 2. Reduction of the oxime (III) with sodium in absolute alcohol afforded 2,5-dimethyltetrahydro-1-thiopyran-4-amine, which by analogy with compounds of the cyclohexane and piperidine series must have the trans-structure (VI). Attempts to prepare the second possible stereoisomer of the amine (V) by reducing the oxime (III) in an acid medium were not successful.

• 3. The same amine (VI) was obtained in 14% yield by the action of metallic sodium in alcoholic ammonia solution on the thiopyrone (I).

• 4. The hydrochloride (VII), the acetyl derivative (VIII), and the benzoyl derivative (IX) of the thiopyran amine, and also the hydrochloride (X) and the benzoyl derivative (XII) of the aminosulfone, and the hydrochloride of the aminosulfoxide (XI) have been prepared.

• 5. It is shown that the oxime of the tetrahydropyran series (III) rearranges to the lactam (XIII) or (XIV) on heating with sulfuric acid; hydrolytic cleavage of the lactam gave the thioamino acid (XVII) or (XVIII).

• 6. The thiosemicarbazones of 2,5-dimethyltetrahydro-1-thiopyran-4-one (XIX) and its correspondiug sulfone (XX), and the semicarbazone of dihydroxy-2,5-dimethyltetrahydro-1-thiopyran-4-one (XXI) have been prepared.