1334680-29-3Relevant academic research and scientific papers
Wolff rearrangement of β-alkynyl-α-diazo-β-ketoesters: Light-induced acetylene-allene isomerization and its use for activation of enediynes
Zhegalova, Natalia G.,Popik, Vladimir V.
, p. 969 - 975 (2012/01/13)
Irradiation of β-phenylethynyl-α-diazo-β-ketoester with 300 or 350nm light results in efficient and regioselective Wolff rearrangement producing only the product of alkynyl group migration. Addition of alcohols to the resulting α-oxoketene yields α-phenylethynyl-β-diester, which undergoes rapid (τ1min) tautomerization to 1,1-dicarbalkoxyallene. The latter then adds second molecule of alcohol in Michael fashion to form the final product, 2-(1-alkoxy-2-phenylvinyl)malonic ester. α-Phenylethynyl- β-ketoacid produced from the ketene in aqueous solutions does not isomerize to an allene but rather undergoes decarboxylation to give β,γ- acetylenic ester. Introduction of o-(3-hydroxy-1-propynyl) fragment in the structure of the parent α-diazo-β-ketoester allowed us to achieve two goals simultaneously: ring closure by intramolecular nucleophilic attack of propargyl alcohol on photo-generated ketene and the subsequent acetylene-allene rearrangement. The resulting enyne-allene undergoes spontaneous Myers-Saito cycloaromatization generating 1,4-biradical. In alcohol solutions, however, ketene reaction with solvent outcompetes the intramolecular process.
