A Sequential One‐Pot Synthesis of Functionalized Esters and Thioesters through a Ring‐Opening Acylation of Cyclic Ethers and Thioethers

A one‐pot protocol for the synthesis of functionalized esters and thioesters is reported from cyclic ethers/thioethers and carboxylic acids via acyloxyphosphonium salts as key intermediates. The reaction of styrene oxide with acyloxyphosphonium salts gave complete regioselectivity and good yields of the resulting functionalized ester, whereas cyclohexene oxide gave moderate yields. Styrene episulfide, on the other hand, gave good yields with moderate regioselectivity whereas cyclohexene sulfide gave quantitative yields of the corresponding thioesters. We have also shown an alternate procedure for the ring opening of THF to form 4‐bromo butyl esters. All these reactions were carried out in the absence of a catalyst, showing the synthetic versatility of our method.