Institute of Marine Biomedicine, Shenzhen Polytechnic, Shenzhen 518055, China.
State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China.
Org Biomol Chem. 2020 Apr 15;18(15):2949-2955. doi: 10.1039/d0ob00224k.
A novel and practical protocol for the synthesis of fully substituted pyrazoles from pyridinium 1,4-zwitterionic thiolates and hydrazonoyl chlorides in excellent yields under mild conditions is described. The transformation proceeds via an unusual [[3 + 3] - 1] pathway, which involves a formal [3 + 3] cascade cyclization followed by a spontaneous ring-contraction/sulfur extrusion reaction from 4H-1,3,4-thiadiazine intermediates.
本文描述了一种新颖实用的方法，可在温和条件下高产率地从吡啶鎓 1,4-双硫代叶立德和酰肼氯出发合成完全取代的吡唑。该转化通过一种不寻常的 [[3 + 3] - 1] 途径进行，涉及一个[3 + 3]级联环化，随后从 4H-1,3,4-噻二嗪中间体中自发进行环收缩/硫消除反应。
