Palladium-catalyzed C-P Bond Activation Of Aroyl Phosphine Oxides

The research is mainly about the Pd-catalyzed C-P bond activation of aroyl phosphine oxides.Decarbonylation reaction was choosed as model reaction to for exploration on C-P bond activation of aroyl phosphine oxides.After the exploration of the reaction conditions,it is found that Pd(PCy3)4 complex formed in situ is the best catalyst for the C-P bond activation of aroyl phosphine oxides to.generate phosphine oxides via decarbonylation.Moreover,when the amount of palladium catalyst is reduced to 2 mol%,the reaction can also occur well.To further demonstrate the generality of this novel protocol,we examined the scope aroyl phosphine oxides.And found that most of the naphthyl phosphine oxides can react smoothly,while the phenyl phosphine oxides with o-substitution can also react well.Meanwhile,aroyl phosphine oxides with thienyl or biaryl all can give products in excellent yield.And the highest separation yield can reach 97%.In a word,the C-P bond activation reaction has good substrate adaptability and functional group compatibility,and the steric hindrance has little effect on the reaction.At last,we studied the mechanism of the C-P bond activation via radical capture experiments.And found that the reaction goes smoothly with the existence of radical scavenger,which suggested that radical mechanism involved the reaction can be excluded.On the basis of these experiments and literatures,we supposed that the reaction may go though oxidation addition-reduction elimination mechanism.This research promotes the prolongation of the C-P bond activation,and it is the first time to construct phosphine compounds using the C-P bond activation strategy.