Synthesis of 4'-(4-Ethyl-phenylethynyl)-3,5,2',6'-tetrafluoro-biphenyl-4-ylamine
4'-(4-Ethyl-phenylethynyl)-3,5,2',6'-tetrafluoro-biphenyl-4-ylamine(3)is a key intermediate of fluorotolane liquid crystal compounds.Due to the poor stability of 2,6-difluoro-4-phenylethynyl-phenylboronic acid,it is difficult for the synthesis of 3.However,the target product 3 can be synthesized via Suzuki Coupling with 2,which is the intermediate of 2,6-difluoro-4-iodoaniline and bis(pinacolato)diboron,and 1,which is the sonogashira coupling product of 4-ethylphenylacetylene and 2-bromo-1,3-difluoro-5-(4-ethylphenylethynyl)benzene.The structure was confirmed by 1H NMR,ESI-MS,etc.,and the synthetic process was optimized with an overall yield of 70％,and the purity was 99.5％(HPLC).
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