Synthesis 2016; 48(05): 737-750
DOI: 10.1055/s-0035-1560386
paper
© Georg Thieme Verlag Stuttgart · New York

Site-Selective N-Arylation of Carbazoles with Halogenated Fluorobenzenes

Lei Wang
School of Chemistry and Chemical Engineering, Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, Shihezi University, North 4th Road, Shihezi, Xinjiang 832003, P. R. of China   Email: ninglau@163.com   Email: dbinly@126.com
,
Enhui Ji
School of Chemistry and Chemical Engineering, Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, Shihezi University, North 4th Road, Shihezi, Xinjiang 832003, P. R. of China   Email: ninglau@163.com   Email: dbinly@126.com
,
Ning Liu*
School of Chemistry and Chemical Engineering, Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, Shihezi University, North 4th Road, Shihezi, Xinjiang 832003, P. R. of China   Email: ninglau@163.com   Email: dbinly@126.com
,
Bin Dai*
School of Chemistry and Chemical Engineering, Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, Shihezi University, North 4th Road, Shihezi, Xinjiang 832003, P. R. of China   Email: ninglau@163.com   Email: dbinly@126.com
› Author Affiliations
Further Information

Publication History

Received: 26 September 2015

Accepted after revision: 11 November 2015

Publication Date:
28 December 2015 (online)


Abstract

A method for the highly site-selective C–N bond-formation reaction of halogenated fluorobenzenes with carbazoles is described. The selectivity of iodine and fluorine atoms on the aromatic ring of fluorinated iodobenzenes was initially determined with a copper–N,N-diisopropylethylamine catalytic system. By changing the position of the iodine atom on the aromatic ring from the 3- or 4-position to the 2-position, the preferred coupling site was switched from the iodine atom to the fluorine atom. Steric hindrance of the fluorinated iodobenzenes is responsible for the selectivity switch. After elucidating the reaction mechanisms of these reaction processes, a metal-free method for the highly site-selective C–N bond-formation reaction of halogenated fluorobenzenes with carbazoles was revealed through C–F bond activation. The metal-free system is able to handle a range of halogenated groups. Thus, a broad range of chlorinated, brominated, and iodinated N-arylated carbazoles were generated, which are widely useful in organic chemistry.

Supporting Information