Practical C-H Functionalization of Quinones with Boronic Acids
Yuta Fujiwara, Victoriano Domingo, Ian B. Seiple, Ryan Gianatassio, Matthew Del Bel, and Phil S. Baran*
*Department of Chemistry and Chemical Biology, The Scripps
Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037,
United States, Email: pbaran
scripps.edu
Y. Fujiwara, V. Domingo, I. B. Seiple, R. Gianatassio, M. Del Bel, P. P. S. Baran, J. Am. Chem. Soc., 2011, 133, 3292-3295.
DOI: 10.1021/ja111152z
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Abstract
A scalable, direct functionalization of various quinones with several boronic acids proceeds readily at room temperature in an open flask using catalytic silver(I) nitrate in the presence of a persulfate co-oxidant. The scope with respect to quinones is broad, with a variety of alkyl- and arylboronic acids undergoing efficient cross-coupling.
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Arylation of Quinones: Standard Procedure.
To a solution of benzoquinone (0.25 mmol, 1.0 equiv) in dichloromethane (or trifluorotoluene where noted, 1.25 mL) was added the corresponding boronic acid (0.375 mmol, 1.5 equiv), water (0.75 mL), and silver(I) nitrate (0.1 M solution in water, 8.5 mg, 0.05 mmol, 0.2 equiv). Potassium persulfate (202 mg, 0.75 mmol, 3.0 equiv) was then added and the solution was stirred vigorously at room temperature and monitored by thin-layer chromatography analysis of the organic layer. If necessary, a second addition of solid silver(I) nitrate (8.5 mg, 0.05 mmol, 0.2 equiv) and potassium persulfate (202 mg, 0.75 mmol, 3.0 equiv) was added. Upon consumption of quinone (3 - 24 h total), the reaction was diluted with dichloromethane (3 mL) and washed with 5% sodium bicarbonate. The layers were separated, and the aqueous layer was extracted with dichloromethane (3 X 4 mL), dried over sodium sulfate, and evaporated in vacuo. Purification was performed by silica gel chromatography to yield chromatographically and spectroscopically pure product.
Key Words
Cyclic Enones, Arylation, Potassium Peroxydisulfate
ID: J48-Y2011-0500
