Zhou Lu, Chen Zhaopeng, Li Jiahui, Li Baolin
School of Chemical Sciences, University of Chinese Academy of Sciences Beijing 100049 P. R. China
RSC Adv. 2021 Oct 21;11(54):34071-34078. doi: 10.1039/d1ra06881d. eCollection 2021 Oct 18.
We have developed a mild catalytic approach for the synthesis of new dithienofuran derivatives cascade copper catalysed dual C-S coupling and subsequent ring closure reactions. Sonogashira coupling between perbromofuran and terminal alkynes produced 3,4-dibromo-2,5-dialkynylfuran (1) in good yields. Next, copper catalysed C-S coupling between 1 and NaS·9HO and a subsequent ring-closure reaction afforded dithienofuran compounds (2) under mild conditions. We found that this strategy shows broad substrate scope and can be used to prepare not only aryl and heteroaryl but also alkyl substituted dithienofuran derivatives in up to 70% yields. Furthermore, we proposed a mechanism including two catalytic cycles: a typical Cu(i)/Cu(iii) catalytic cycle and a subsequent Cu(ii) induced cyclization mechanism.
我们已经开发出一种温和的催化方法来合成新的二噻吩并呋喃衍生物，该方法涉及串联铜催化的双C-S偶联及随后的闭环反应。全溴代呋喃与末端炔烃之间的Sonogashira偶联反应以良好的产率生成了3,4-二溴-2,5-二炔基呋喃（1）。接下来，1与NaS·9H₂O之间的铜催化C-S偶联反应以及随后的闭环反应在温和条件下得到了二噻吩并呋喃化合物（2）。我们发现该策略具有广泛的底物范围，可用于制备芳基、杂芳基以及烷基取代的二噻吩并呋喃衍生物，产率高达70%。此外，我们提出了一种包含两个催化循环的机理：一个典型的Cu(i)/Cu(iii)催化循环以及随后的Cu(ii)诱导环化机理。
