Acta Chimica Sinica ›› 2023, Vol. 81 ›› Issue (6): 577-581.DOI: 10.6023/A23040127 Previous Articles     Next Articles

Communication

基于氟仿衍生的三氟甲基硼络合物参与的烯烃氢三氟甲基化反应

李飞a, 丁汇丽b, 李超忠a,b,*()   

  1. a 中国科学技术大学化学系 合肥 230026
    b 中国科学院上海有机化学研究所有机氟化学重点实验室 上海 200032
  • 投稿日期:2023-04-11 发布日期:2023-05-16
  • 基金资助:
    国家自然科学基金(22193014); 国家自然科学基金(21971253); 中国科学院(ZDBS-LY-SLH026); 中国科学院青年促进会(2020257); 上海市科学技术委员会(21ZR1476700); 上海市科学技术委员会(21YF1456300)

Hydrotrifluoromethylation of Alkenes with a Fluoroform-Derived Trifluoromethylboron Complex

Fei Lia, Huili Dingb, Chaozhong Lia,b()   

  1. a Department of Chemistry, University of Science and Technology of China, Hefei 230026
    b Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032
  • Received:2023-04-11 Published:2023-05-16
  • Contact: * E-mail: clig@mail.sioc.ac.cn
  • Supported by:
    National Natural Science Foundation of China(22193014); National Natural Science Foundation of China(21971253); Chinese Academy of Sciences(ZDBS-LY-SLH026); Youth Promotion Association (2020257) of CAS and the Science and Technology Commission of Shanghai Municipality(21ZR1476700); Youth Promotion Association (2020257) of CAS and the Science and Technology Commission of Shanghai Municipality(21YF1456300)

Trifluoromethyl-containing organic compounds have found widespread applications in various areas such as pharmaceuticals, agrochemicals and materials science. Fluoroform is the cheapest and most atom-economical trifluoromethyl source, but chemically inert. The use of fluoroform in trifluoromethylation reactions remains a formidable challenge. In this work, with a trifluoromethylboron complex derived from fluoroform as the trifluoromethylating reagent, the hydrotrifluoromethylation of styrenes, acrylates and acrylamides is successfully accomplished under photoredox catalytic conditions. Thus, with potassium bis(trimethylsilyl)amide (KHMDS) as the base, the reaction of fluoroform with (4-methoxyphenyl)boronic acid pinacol ester at room temperature (r.t.) leads to the corresponding trifluoromethylboron complex in 59% yield as a white solid stable in air and moisture. With the ate complex as the trifluoromethylating reagent, 1,2,3,5-tetrakis(carbazol-9-yl)-4,6- dicyanobenzene (4CzIPN) as the photocatalyst and benzoic acid as the proton source, the reaction of styrenes in N,N-dimethylacetamide (DMA) at r.t. under blue light irradiation provided the corresponding anti-Markovnikov hydrotrifluoromethylation products in satisfactory yields. The protocol is also applicable to various acrylates as well as acrylamides, furnishing the expected -trifluoromethylated esters or amides. A wide functional group compatibility is observed. The reaction is efficient and highly regioselective. In addition, the pinacol boronate generated along with the hydrotrifluoromethylation products can be recovered and reused. A redox-neutral mechanism is proposed, which involves the oxidative generation of CF3 radicals, addition to C=C bonds, subsequent single electron reduction and protonation.

Key words: trifluoromethylation, fluoroform, trifluoromethylboron complex, photocatalysis, hydrotrifluoromethylation