The ring-opening and rearrangement reaction of 7-methyl-5H-1,3,4-thiadiazolo[3,2-a]pyrimidin-5-ones (I) and the alternative isomeric 7-ones (XI) has been studied. I (R=H) and XI (R=H) gave quantitatively through N–N bond cleavage methylthiouracil (III) by treating with 5% NaOH, while they yielded 4-methyl-2-thiocyanato-6(1H)pyrimidone (II) by treating with liquid ammonia. By treating I and XI (R=alkyl) with 5% NaOH, the S–C bond cleaved to produce the corresponding acylaminopyrimidine derivatives (IV and IV′) and 3-aminopyrimidinethione (V and V′). The treatment of 2-hydrazino derivative (I; R=NHNH2) with 5% NaOH gave 1-amino-2-mercapto-7-methyl-5H-s-triazolo[1,5-a]pyrimidin-5-one (VIII) through ring-opening and recyclization. On the other hand, the pyrimidine moiety of I (R=Et and i-Pr) cleaved by the action of chlorine to afford 2-amino-1,3,4-thiadiazole (X; R=Et and t-Pr).
                                    研究了 7-甲基-5H-1,3,4-
噻二唑并[3,2-a]
嘧啶-5-酮 (I) 和替代异构体 7-酮 (XI) 的开环和重排反应。 I (R=H) 和 XI (R=H) 用 5% NaOH 处理,通过 N-N 键断裂定量给出甲基
硫氧
嘧啶 (III),同时得到 4-甲基-2-
硫氰酸基-6(1H)
嘧啶酮 (II) )通过用液
氨处理。通过用 5% NaOH 处理 I 和 XI(R=烷基),S-C 键断裂,生成相应的酰
氨基嘧啶衍
生物(IV 和 IV')和 3-
氨基嘧啶硫酮(V 和 V')。用 5% NaOH 处理 2-
肼基衍
生物 (I; R=NHNH2) 得到 1-
氨基-2-巯基-7-甲基-5H-s-三唑并[1,5-a]
嘧啶-5-酮 (VIII )通过开环和回收。另一方面,I的
嘧啶部分(R=Et和i-Pr)在
氯的作用下裂解,得到
2-氨基-1,3,4-噻二唑(X;R=Et和t-Pr)。