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Base‐Catalyzed Synthesis of Substituted Indazoles under Mild, Transition‐Metal‐Free Conditions
Author(s) -
Thomé Isabelle,
Besson Claire,
Kleine Tillmann,
Bolm Carsten
Publication year - 2013
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201300917
Subject(s) - catalysis , transition metal , yield (engineering) , chemistry , combinatorial chemistry , computer science , materials science , organic chemistry , metallurgy
Back to basics : A transition‐metal‐free method developed for the synthesis of indazoles involves an inexpensive catalytic system composed of a diamine and K 2 CO 3 . Various ( Z )‐2‐bromoacetophenone tosylhydrazones were converted into indazoles at room temperature in excellent yields (see example; Ts= p ‐toluenesulfonyl). The yield was improved by photoisomerization with UV light when E / Z isomeric mixtures of the starting material were used.