Tosyloxybenziodoxolone: A Platform for Performing the Umpolung of Alkynes in One-Pot Transformations
Julien Borrel and Jerome Waser*
*Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCSO, BCH 1402, 1015 Lausanne, Switzerland,
Email: jerome.waser
epfl.ch
J. Borrel, J. Waser, Org. Lett., 2022, 24, 142-146.
DOI: 10.1021/acs.orglett.1c03771
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Abstract
Ethynylbenziodoxolones (EBXs) are useful reagents for the electrophilic alkynylation of nucleophiles. One-pot, two-step processes for EBX generation and their direct reaction with two- and one-electron nucleophiles even allow to bypass the originally mandatory isolation and purification of the reagents, resulting in more efficient syntheses of alkynylated products.
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examples of two-step processes
General procedure
A capped oven dried microwave vial charged with 1-(p-methylbenzenesulfonyloxy)-1,2-benziodoxol-3-(1H)-one (167 mg, 0.400 mmol, 1.0 equiv.) and potassium alkynyltrifluoroborate (0.50 mmol, 1.25 equiv.) was evacuated and backfilled with N2 (3x). Dry acetonitrile (4 mL) was added under N2 and the reaction was stirred at rt for 1 h. To the mixture was added a sat. sol. of NaHCO3 (8 mL) and the mixture was vigorously stirred open to air for 1 h. Water (10 mL) was added and the mixture was extracted with 3 x 20 mL of DCM, the combined organic layers were dried over MgSO4, filtered and concentrated in vacuo. The crude EBX was triturated in pentane, which induced precipitation if it was an oil. The pentane layer was discarded with care to leave the solid in the flask. This process was repeated 2 more times then the solid was dried in vacuo to afford the desired product.
R. Frei, M. D. Wodrich, D. P. Hari, P.-A. Borin, C. Chauvier, J. Waser, J. Am. Chem. Soc., 2014, 136, 16563-16573.
H. Huang, G. Zhang, L. Gong, S. Zhang, Y. Chen, J. Am. Chem. Soc., 2014, 136, 2280-2283.
Key Words
ID: J54-Y2022
