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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.

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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 30C, 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