(R)‐2‐(4‐(Benzo[d]oxazol‐2‐yl)piperazin‐1‐yl)‐4‐((tetrahydro‐2H‐pyran‐4‐yl)amino)‐6,7‐dihydrothieno[3,2‐d]pyrimidine 5‐oxide (1) and (R)‐2‐(4‐(4‐chlorophenoxy)piperidin‐1‐yl)‐4‐((tetrahydro‐2H‐pyran‐4‐yl)amino)‐6,7‐dihydrothieno[3,2‐d]pyrimidine 5‐oxide (2) are two potent and selective inhibitors of phosphodiesterase type 4 (PDE4). In this manuscript, we report the detailed synthesis of these two compounds labeled with carbon 14 and with stable isotopes. The core (R)‐4‐((tetrahydro‐2H‐pyran‐4‐yl)amino)‐6,7‐dihydrothieno[3,2‐d]pyrimidine 5‐oxide is common in both inhibitors. In the radioactive synthesis, the carbon 14 atom was introduced in the benzoxazole moiety using [14C]carbon disulfide to obtain [14C]‐1 in five steps at a 55% overall yield. [14C]Urea was used to incorporate the carbon 14 atom in two steps in the dihydrothieno[3,2‐d]pyrimidine intermediate, which was then transformed in four more steps to [14C]‐2 at a 30% overall yield. Both compounds were isolated with specific activities higher than 54 mCi/mmol, radio‐ and chemical‐purities higher than 99%, and with excellent enantiomeric excess. In the stable isotope synthesis, [2H8]piperazine was used to prepare [2H8]‐1 in three steps in 72% overall yield, while [13C6]phenol was used to prepare [13C6]‐2 in four steps in 18% overall yield.
(R)-2-(4-(苯并[d]
恶唑-2-基)
哌嗪-1-基)-4-((四氢-
2H-吡喃-4-基)
氨基)-6,7-二氢
噻吩并[3、(1)和(R)-2-(
4-(4-氯苯氧基)哌啶-1-基)-4-((四氢-
2H-吡喃-4-基)
氨基)-6,7-二氢
噻吩并[3,2-d]
嘧啶 5-氧化物(2)是两种强效的 4 型
磷酸二酯酶 (PDE4) 选择性
抑制剂。)在本手稿中,我们报告了这两种用碳 14 和稳定同位素标记的化合物的详细合成过程。(R)-4-((tetrahydro-2H-pyran-4-yl)amino)-6,7-dihydrothieno[3,2-d]pyrimidine 5-oxide 是这两种
抑制剂的共同核心。在放射性合成中,使用[14C]
二硫化碳在
苯并恶唑分子中引入碳 14 原子,通过五个步骤得到[14C]-1,总收率为 55%。用[14C]
脲分两步在二氢
噻吩并[3,2-d]
嘧啶中间体中加入碳 14 原子,然后再分四步转化为[14C]-2,总收率为 30%。分离出的这两种化合物的比活度均高于 54 mCi/mmol,放射性和
化学纯度均高于 99%,对映体过量性极佳。在稳定同位素合成中,用[2H8]
哌嗪分三步制备了[2H8]-1,总收率为 72%,而用[13C6]
苯酚分四步制备了[13C6]-2,总收率为 18%。