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Directing/Protecting‐Group‐Free Synthesis of Tetraaryl‐Substituted Pyrazoles through Four Direct Arylations on an Unsubstituted Pyrazole Scaffold
Author(s) -
Fuse Shinichiro,
Morita Taiki,
Johmoto Kohei,
Uekusa Hidehiro,
Tanaka Hiroshi
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201502399
Subject(s) - pyrazole , aryl , reagent , chemistry , protecting group , combinatorial chemistry , scaffold , group (periodic table) , medicinal chemistry , organic chemistry , biomedical engineering , medicine , alkyl
A directing/protecting‐group‐free synthesis of 1,3,4,5‐tetraaryl‐substituted pyrazoles was achieved through four transition metal‐catalyzed direct arylations. Various pyrazoles with four different aryl rings were obtained using readily available reagents from an unsubstituted pyrazole. Two aryl‐substituted pyrazoles showed intense violet fluorescence, high quantum yields ( Φ f =0.68, 0.64), and large Stokes shifts (19000, 15200 cm −1 ).