Transformation of Thioacids into Carboxylic Acids via a Visible-Light-Promoted Atomic Substitution Process

Rui Wang*, Kai-jun Xie, Qiang Fu, Min Wu, Gao-feng Pan, Da-wei Lou* and Fu-Shun Liang*

*Jilin Institute of Chemical Technology, Jilin 132022; College of Chemistry, Liaoning University, Shenyang 110036, China, Email: wangrjlict.edu.cn, dwloujlict.edu.cn, fslianglnu.edu.cn

R. Wang, K.-j. Xie, Q. Fu, M. Wu, G.-f. Pan, W.-w. Lou, F.-S. Liang, Org. Lett., 2022, 24, 2020-2024.

DOI: 10.1021/acs.orglett.2c00481

---

Abstract

Visible-light promotes an atomic substitution reaction of thiocacids to afford various alkyl and aryl carboxylic acids in over 90% yields with dimethyl sulfoxide (DMSO) as the oxygen source. The atomic substitution process proceeds smoothly through the photochemical reactivity of the formed hydrogen-bonding adduct between thioacids and DMSO.

see article for more examples

proposed mechanism

---

---

Representative procedure for the preparation of carboxylic acids:

A transparent 25 mL round-bottomed flask (high borosilicate glass), equipped with a magnetic stirring bar, was charged with thioacid (1.0 mmol) and C₄F₉I (10 mmol%, 17.38 μL) in DMSO (5 mL) and degassed three time with N₂. The reaction mixture was irradiated with 12 W blue LEDs (5 cm away with cooling fan to keep the reaction to approximately 30°C, see below). After the starting material was consumed as indicated by TLC, the reaction mixture was poured into water and then extracted with CH₂Cl₂ (3 x 10 mL). The combined organic phase was washed with water (3 x 10 mL), dried over anhydrous MgSO₄, filtered and concentrated under reduced pressure. The crude product was purified by flash chromatography on 200-300 mesh silica gel using first petroleum ether/ethyl acetate (80/1 or 120/1, v/v), and finally ethyl acetate as an eluent to give the desired product.

---

Key Words

carboxylic acids, photochemistry

---

ID: J54-Y2022