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Site‐Selective Sonogashira Reactions of 1,4‐Dibromo‐2‐fluorobenzene – Synthesis and Properties of Fluorinated Alkynylbenzenes
Author(s) -
Reimann Sebastian,
Sharif Muhammad,
Hein Martin,
Villinger Alexander,
Wittler Kai,
Ludwig Ralf,
Langer Peter
Publication year - 2012
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201100394
Subject(s) - fluorobenzene , chemistry , sonogashira coupling , regioselectivity , steric effects , differential scanning calorimetry , photochemistry , trifluoromethyl , selectivity , liquid crystal , fluorescence , organic chemistry , benzene , palladium , catalysis , physics , alkyl , quantum mechanics , optics , thermodynamics
A variety of alkynyl‐substituted fluorinated benzene derivatives have been prepared by Sonogashira cross‐coupling reactions of 1,4‐dibromo‐2‐fluorobenzene. The reactions proceed with very good site‐selectivity in favor of the 4‐position because of electronic and steric reasons. The regioselectivity is explained by the results of DFT calculations. The absorption and emission (fluorescence) properties of the products, mono‐ and dialkynylated fluorobenzenes, have been studied. In addition, the mesomorphic properties of the products have been investigated by polarization microscopy and differential scanning calorimetry. 1,4‐Dialkynyl‐2‐fluorobenzenes show nematic liquid‐crystalline properties over a long phase range.