Phosphaannulation of Aryl- and Benzylphosphonic Acids with Unactivated Alkenes via Palladium-Catalyzed C-H Activation/Oxidative Cyclization Reaction

An efficient phosphaannulation via palladium( II)-catalyzed C-H activation/oxidative cyclization by the 6-endo mode is reported for the synthesis of 3-substituted phosphaisocoumarins from the reaction of arylphosphonic acids with unactivated alkenes under aerobic conditions. Also, alpha,alpha-disubstituted benzylphosphonic acids were phosphaannulated with unactivated alkenes, producing phosphaisochromanones having (Z)-alkylidenyl groups via anti-phosphoryloxypalladation by the 6-exo mode.