- Boron(III)-Catalyzed C2-Selective C?H Borylation of Heteroarenes
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A BF3?Et2O-catalyzed C2-selective C?H borylation of indoles with bis(pinacolato)diboron was developed to afford indole-2-boronic acid pinacol esters. A variety of functional groups were tolerated, and other heteroarenes like pyrrole and benzo[b]thiophene were also suitable substrates. An electrophilic substitution mechanism was proposed based on the preliminary mechanistic studies. This novel transformation utilizes simple and cheap BF3?Et2O as catalyst and exhibits unusual C2 regioselectivity, providing a significant non-transition-metal-catalyzed C?H borylation and an efficient method towards the synthesis of C2-functionalized heteroarenes.
- Zhong, Qi,Qin, Shengxiang,Yin, Youzhi,Hu, Jiajun,Zhang, Hua
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p. 14891 - 14895
(2018/10/20)
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- Use of α-Anilino Dienenitriles as Nucleophiles in Cycloadditions
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The α-anilino dienenitriles 1-5 were prepared.The dienes 1-3 reacted with dichlorocarbene and electrophiles containing electron-deficient double bonds such as maleic anhydride, benzoquinone, dimethyl acetylenedicarboxylate, tetracyanoethylene, and chlorosulphonyl isocyanate.The diarylmethylamines 8-10, generated by cycloaddition of α-anilino dienenitriles and maleic anhydride, were successfully transformed into acridones 15-17.Intramolecular cyclization of trienes 4 and 5 yielded the carbazoles and dihydro derivatives, accompanied by formation of 2-cyano-1-methylindole.
- Fang, Jim-Min,Yang,Chau-Chen,Wang, Yu-Wen
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p. 477 - 481
(2007/10/02)
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