Addition reactions and redox esterifications of carbonyl compounds by N-heterocyclic carbenes of indazole.
Thermal decarboxylation converts 1,2-dimethylindazolium-3-carboxylate into indazol-3-ylidene, which reacts in situ with ketones to form stable 1:1 adducts. When the reaction is conducted with aromatic aldehydes in alcohols, redox esterifications to benzoates are observed. Model reactions such as redox esterifications of aromatic aldehydes with sodium alcoholates in the presence of 1,2-dimethylindazolium salt and oxidations of sodium benzylates by 1,2-dimethylindazolium salt to aldehydes lend support to a Cannizzaro-type mechanism of this reaction.
Institute of Organic Chemistry, Clausthal University of Technology, Leibnizstrasse 6, D-38678 Clausthal-Zellerfeld, Germany. schmidt@ioc.tu-clausthal.de
Andreas
A
Schmidt
Tobias
T
Habeck
Bohdan
B
Snovydovych
Wolfgang
W
Eisfeld