Aryne Insertion Reactions into Carbon-Carbon σ-Bonds

Diverse nucleophilic carbon-electrophilic carbon sigma-bonds were found to undergo facile cleavage and to add across carbon-carbon triple bonds of arynes without the aid of transition-metal catalysts, leading to the direct introduction of different carbon functionalities into the ortho-positions of aromatic rings. Active methylene compounds including beta-dicarbonyl compounds, alpha-cyanocarbonyl compounds, sulfonylacetonitrile, and malononitrile smoothly underwent the aryne insertion reactions, and, moreover, the reaction was applicable to fluorene and trifluoromethyl ketone derivatives. The total synthesis of cytosporone B and phomopsin C, depending upon the carbon-carbon bond cleavage reaction, is also described.