One-Pot Synthesis of 2,3-Disubstituted Indanone Derivatives in Water under Exogenous Ligand-Free and Mild Conditions

Diverse
2,3-substituted indanones are accessed in an efficient
and robust protocol by a rhodium-catalyzed tandem carborhodium/cyclization
and intramolecular proton shift pathway. The reaction is compatible
with a broad range of functional internal acetylenes, especially for
natural and functionalized alkynes derivatives, affording the desired
indanones in good to excellent yields. Remarkably, this reaction features
very mild and sustainable conditions using water as the sole solvent
and without exogenous ligands. Control studies support that indanone
is formed through the intramolecular proton transfer process from
the key intermediate indenol.