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Monday, September 17, 2012
Douglass F. Taber
University of Delaware

C-H Functionalization

Masayuki Inoue of the University of Tokyo oxidized (Tetrahedron Lett. 2011, 52, 4654. ) the alkyl benzene 1 to the nitrate 2, which could be carried on to the amide 5, the nitrile 6, the alcohol 7 or the azide 8.

X. Peter Zhang of the University of South Florida developed (Chem. Sci. 2012, 2, 2361. ) a Co catalyst for the cyclization of 7 to 8. Justin Du Bois of Stanford University reported (J. Am. Chem. Soc. 2011, 133, 17207. ) the oxidative cyclization of the sulfamate corresponding to 7 using a Ru catalyst. Seongmin Lee of the University of Texas showed (Org. Lett. 2011, 13, 4766. ) that the oxidative cyclization of 9 gave the amine 10 with high diastereoselectivity. Fabrizio Fabris of the UniversitÓ di Venezia used (Tetrahedron Lett. 2011, 52, 4478. ) a Ru catalyst to oxidize 11 to the ketone 12. Ying-Yeung Yeung of the National University of Singapore found (Org. Lett. 2011, 13, 4308. ) that hypervalent iodine was sufficient to oxidize 13 to the ketone 14.

Huanfeng Jiang of the South China University of Technology methoxycarbonylated (Chem. Commun. 2011, 47, 12224. ) 15 under Pd catalysis, to give 16. Professor Inoue found (Org. Lett. 2011, 13, 5928. ) that the oxidative cyanation of 17 proceeded with high diastereoselectivity, to give 18. Mamoru Tobisu and Naoto Chatani of Osaka University activated (J. Am. Chem. Soc. 2011, 133, 12984. ) 19 with a Pd catalyst, to enable coupling with 20 to give 21.

Rh-mediated intramolecular insertion is well known to proceed efficiently into secondary and tertiary C-H bonds. A. Srikrishna of the Indian Institute of Science, Bangalore found (Synlett 2011, 2343. ) that insertion into the methyl C-H of 22 also worked smoothly, to deliver 23.

The macrocyclic oligopeptide Valinomycin 24 has nine isopropyl groups. It is remarkable, as observed (Org. Lett. 2011, 13, 5096. ) by Cosimo Annese of the UniversitÓ di Bari and Paul G. Williard of Brown University, that direct oxidation of 24 with methyl(trifluoromethyl)dioxirane in acetone specifically hydroxylated at 8 (45.5%, our numbering), 7 (28.5%), and 6 (26%).

D. F. Taber, Org. Chem. Highlights 2012, September 17.
URL: https://www.organic-chemistry.org/Highlights/2012/17September.shtm