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

Abstract

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.

Arylacetic Acids in Organic Synthesis

“…Using a phosphine reagent (ClP(Bin), PPh 3 ,– PO(osalMe) 3 , polyphosphonic anhydride), arylacetic acids would convert into intermediates 42.1 as a powerful electrophile. 42.1 easily reacted with weak nucleophiles (tertiary amine, THF, styrene episulfide, F‐) to yield aimdes 42.3, esters 42.6 , thioesters 42.7 , 42.8 and acyl fluorides 42.5 (Eq. 42‐1).…”

“…42‐1). In 2018, the Chandrasekaran group described two kinds of ring expansion of heterocyclic compounds with phenylacetic acids (Eq. 42‐2,3).…”

Visible Light-Assisted Ring-Opening of Cyclic Ethers with Carboxylic Acids Mediated by Triphenylphosphine and N-Halosuccinimides

“…1,5 In this regard, Gopinath and Chandrasekaran have developed a one-pot sequential method for the synthesis of ω-bromoalkyl carboxylates via the ringopening of cyclic ethers involving the acyloxyphosphonium salt intermediates. 5 In 2022, Qiu and co-workers realized the synthesis of ω-iodoalkyl carboxylates directly from carboxylic acids via a Cu-catalyzed ring-opening of cyclic ethers. 1 Most recently, our group discovered the formation of halogen bond complexes 6,7 between N-halosuccinimides and enamines 8a or polycyclic aromatic hydrocarbons, 8b which can be used for the direct acyloxylation of ketones or arenes using carboxylic acids under visible light irradiation.…”

“…In addition, a Lewis acid catalyst is also often necessary. Only a few methods have been reported where the readily available carboxylic acids have been used for the direct synthesis of ω-haloalkyl carboxylates. , In this regard, Gopinath and Chandrasekaran have developed a one-pot sequential method for the synthesis of ω-bromoalkyl carboxylates via the ring-opening of cyclic ethers involving the acyloxyphosphonium salt intermediates . In 2022, Qiu and co-workers realized the synthesis of ω-iodoalkyl carboxylates directly from carboxylic acids via a Cu-catalyzed ring-opening of cyclic ethers …”