Organic Chemistry Portal

Abstracts

Search:

Ligand-Controlled Cobalt-Catalyzed Regiodivergent Alkyne Hydroalkylation

Yan Li, Deguang Liu, Lei Wan, Jun-Yang Zhang, Xi Lu* and Yao Fu*

*University of Science and Technology of China, 230026 Hefei, China, Email: luximail.ustc.edu.cn, fuyaoustc.edu.cn

Y. Li, D. Liu, L. Wan, J.-Y. Zhang, X. Lu, Y. Fu, J. Am. Chem. Soc., 2022, 144, 13961-13972.

DOI: 10.1021/jacs.2c06279


see article for more reactions

Abstract

In a ligand-controlled cobalt-catalyzed regiodivergent alkyne hydroalkylation of terminal alkynes with alkyl halides, use of bisoxazoline and pyridine-oxazoline ligands provided (E)-1,2-disubstituted and 1,1-disubstituted alkenes with high E/Z stereoselectivity and regioisomeric ratio. Internal alkynes provide trisubstituted alkenes. The methods show excellent functional group compatibility.


see article for more examples



General procedure

In air, a 10 mL screw-cap test tube equipped with a magnetic stirrer was charged with ligand (0.03 mmol, 15 mol%), CoBr2(DME) (0.02 mmol, 10 mol%), and CsF (0.6 mmol, 3.0 equiv.) (if the alkyne or the alkyl halide were solid, they were also added at this time). The test tube was evacuated and backfilled with argon three times. Then, DME (1.4 mL) was added, followed by the alkyne (0.4 mmol, 2.0 equiv.) and alkyl halide (0.2 mmol, 1.0 equiv.). The resulting solution was stirred for 10 min at 0 C. Then, DEMS (0.6 mmol, 3.0 equiv.) was added dropwise slowly via a syringe, and the solution was stirred for 1 min at 0 C, followed by stirring at 5 C for 8 h. The reaction mixture was diluted with H2O followed by extraction with EtOAc, dried with anhydrous Na2SO4 and concentrated in vacuo. The residue was purified by flash column chromatography on silica gel to obtain the target product.


Key Words

alkylation, alkenylation of amides, DEMS


ID: J48-Y2022