Base-mediated insertion reaction of alkynes into carbon-carbon σ-bonds of ethanones: synthesis of hydroxydienone and chromone derivatives.

Transition-metal free insertions of alkynes into carbon-carbon σ-bonds of ethanones have been reported. These tandem reactions offer an efficient synthesis of hydroxydienones and multi-substituted chromones. This is the first example of base-promoted insertion reactions of isolated carbon-carbon triple bonds into carbon-carbon σ-bonds with active methylene compounds bearing only one electron-withdrawing group.