443126-41-8Relevant academic research and scientific papers
Electrochemically-induced spirolactonization of α-(methoxyphenoxy)alkanoic acids into quinone ketals
Deffieux, Denis,Fabre, Isabelle,Courseille, Christian,Quideau, Stephane
, p. 4458 - 4465 (2007/10/03)
Anodic oxidation of two series of α-(2)- and α-(4-methoxyphenoxy)alkanoic acids were studied both at the analytical and preparative scales in order to delineate mechanistic aspects of electrochemically induced spirolactonization and to develop synthetically useful orthoquinone bis- and monoketals. Although α-monomethylated carboxylic acids and acetic acid derivatives do not undergo any spiroannulation, α-dimethylated carboxylic acids furnished spirolactones in high yields. A gem-dimethyl effect is invoked to explain these differences in cyclization capacity. Electrooxidation conditions can be selected to furnish either quinone spirolactone bis- or monoketals. Chemoselective monohydrolysis of bisketals can also be accomplished in a stepwise fashion to furnish the corresponding spirolactone monoketals, but the ortho compound unfortunately dimerized in situ via a Diels-Alder process. An ECEC pathway is proposed to rationalize the observed spirolactonizations on the basis of cyclic voltammetry analyses.
