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Copper-Catalyzed Oxidative Decarboxylative Couplings of Sulfoximines and Aryl Propiolic Acids

Daniel L. Priebbenow, Peter Becker and Carsten Bolm*

*Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany, Email: carsten.bolmoc.rwth-aachen.de

D. L. Priebbenow, P. Becker, C. Bolm, Org. Lett., 2013, 15, 6155-6157.

DOI: 10.1021/ol403106e


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Abstract

A copper-catalyzed decarboxylative coupling of sulfoximines with aryl propiolic acids enables the preparation of N-alkynylated sulfoximines. Various substituents on both the sulfoximidoyl moiety as well as the aryl group of the propiolic acid were tolerated.


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General Procedure for the preparation of N-alkynylated sulfoximines:

To an oven dried Schlenk tube was added sulfoximine (1.5 equiv, 0.60 mmol), CuBr (6 mg, 10 mol%), pyridine (6.3 mg, 20 mol %), K3PO4 (93 mg, 1.1 equiv, 0.44 mmol) and PhMe (3 mL). The resultant solution was heated to 80C, and then aryl propiolic acid (1.0 equiv., 0.40 mmol) was added portion wise over 2 minutes. The Schlenk tube was left open to the air and the reaction mixture was heated at 80C for 16 hours. After this time, the mixture was cooled to room temperature and the solvent was evaporated. The product was purified on basic alumina oxide (initially activity stage I deactivated by adding 10 mL deionized water per 200 mL Al2O3) using gradient elution [100% pentane (50 mL), then 1:9 EtOAc/pentane (50 mL), then 1:2 EtOAc/pentane (150 mL)] to afford the N-alkynylated sulfoximine (typical Rf = 0.5 in 2:3 EtOAc/pentane).


Key Words

sulfoximines, oxygen


ID: J54-Y2013