Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry and University of Chinese Academy of Sciences, Chinese Academy of Sciences , Beijing 100190, P. R. China.
J Org Chem. 2016 Aug 19;81(16):7127-33. doi: 10.1021/acs.joc.6b00992. Epub 2016 Jul 14.
A novel efficient tandem reaction of hydrazones and α-bromo ketones is reported for the preparation of 1,3,5-trisubstituted pyrazoles by visible light catalysis. In this system, the monosubstituted hydrazones show wonderful reaction activity with alkyl radicals, generated from α-bromo ketones. A radical addition followed by intramolecular cyclization affords the important pyrazole skeleton in good to excellent yields. This efficient strategy under mild conditions with wide group tolerance provides a potential approach to the 1,3,5-trisubstituted pyrazoles.
本文报道了一种通过可见光催化合成 1,3,5-三取代吡唑的新型高效串联反应，该反应涉及腙和α-溴代酮。在该体系中，单取代腙与α-溴代酮生成的烷基自由基反应活性很高。自由基加成后进行分子内环化，以良好到优秀的收率得到重要的吡唑骨架。该方法在温和条件下、基团容忍度较宽，具有很高的效率，为 1,3,5-三取代吡唑的合成提供了一种潜在方法。
