Highly Selective Transition-Metal-Free Aroylation And Oxidation Of Diarylmethanes

1,2,2-triarylethanones skeleton constitutes a large various of active natural products and parent nuclear skeletons of drugs,so the research on its synthesis methods has been widely concerned.In the past decades,excellent transition metal catalysts have been introduced in the synthesis of 1,2,2-triarylethanones via the?-arylation of ketone enolates.Despite the popurlarity and utility of these reactions,there remains room for improvement,such as:milder reaction conditions,better chemoselectivity,reduced costs,and elimination of transition metal catalysts that ultimately generate waste that must be separated from the products.To avoid these drawbacks,it's crucial to develop a more environmentally friendly,and operate simply method for synthesis of 1,2,2-triarylethanones.Herein,we present two protocols for aroylation of simple diarylmethane derivatives through direct acyl C-N cleavage with N-Bn-N-Boc arylamides and N-acylpyrroles,and direct acyl C-C cleavage with imidazolium salts under metal-free conditions.There are mainly three aspects for the aroylation of simple diarylmethane derivatives:1.Synthesis of 1,2,2-triarylethanones through direct acyl C-N cleavage:we designed and synthesized various of substituted N-Bn-N-Boc arylamides and N-acylpyrroles,which served as the substrates for aroylation of simple diarylmethane derivatives with base under metal-free conditions.Importantly,a 1:1 ratio of the amide to the pronucleophile is employed.Ultimately,30 arylation products were obtained.we scaled up the reaction on a 4 mmol scale result in expected product in satisfied yield.2.Synthesis of 1,2,2-triarylethanones through direct acyl C-C cleavage:we designed and synthesized various of substituted imidazolium salts,which served as the substrates for aroylation of simple diarylmethane derivatives with base under metal-free conditions.Importantly,a 1:1 ratio of the imidazolium salts to the pronucleophile is employed.Ultimately,30 arylation products were obtained.we scaled up the reaction on a 4 mmol scale result in expected product in satisfied yield.3.Among the two methods presented above,we found diary ketones was isolated as by-products,which came from the oxidation of the diarylmethane derivatives.Based on this observation,we developed an effcient direct C?sp³?-H oxidation of diarylmethanes by employing environment-friendly O₂ as an oxidant under metal-free condition.Ultimately,20 oxidantion products were obtained.