Studies On The Phosphorus Trichloride/Iodine Promoted Selective Transformation Of Esters

Ester are widely used in the fields of medicine,pesticides,materials and organic synthesis due to their low toxicity,stability,low-cost and easy availability.At present,methods for the selective transformation of esters still rely on transition-metal catalysis.Therefore,it is very important to develop new methods for the selective and efficient transformation of esters under metal-free conditions.In this paper,a variety of aromatic ketones,nitriles,alkyl aromatic and ketones containing diarylmethane were successfully prepared from esters under the phosphorus trichloride/iodine system.The specific research contents and results are as follows:(1)Under the phosphorus trichloride/iodine system,the acylation of arene with esters was successfully achieved,and aromatic ketones were obtained in high yields.This reaction has a wide substrates scope,esters bearing whether electron-donating groups or electron-withdrawing groups,could react with arene leading to the corresponding products in good yields.What’s more,aromatic esters and alkyl esters are also tolerated under this system.Gram scale reaction was performed,and the product was obtained in excellent yield.The effects of different types of esters were also investigated under this system.Finally,a possible reaction mechanism was proposed based on control experiments.(2)Under the phosphorus trichloride/iodine system,by using acetonitrile as the nitrogen source,the green and efficient conversion of esters into nitriles was successfully achieved.In terms of substrates scope,various aromatic esters and alkyl esters are compatible under this system.The product could also be obtained in moderate yield when the reaction was scaled up to gram-scale.In addition,the effects of different types of esters were tested under this system.Finally,a possible reaction mechanism was proposed.(3)Under the phosphorus trichloride/iodine system,the acylation and alkylation of arene with benzyl benzoate derivatives in one-pot was realized,leading to aromatic ketones and alkyl aromatics simultaneously.The study of substrates scope showed that benzyl alkyl esters and esters containing thiophene were also compatible under this system,besides substrates bearing different electrical groups.In addition,when aromatic esters containing aldehyde group were subjected into the reaction,the Friedel-Crafts alkylation and acylation reactions underwent simultaneously in one-pot,leading to the corresponding ketones,which containing diarylmethane moiety.Control experiments showed that one hydrogen on methylene in the product mainly comes from the benzene ring of arene.Based on the control experiments and previous reports,a possible reaction mechanism was proposed.