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Monday, October 17, 2011
Douglass F. Taber
University of Delaware

Substituted Benzenes: The Piers/Lau Synthesis of Hamigeran B

Govindasamy Sekar of the Indian Institute of Technology, Madras developed (Chem. Commun. 2011, 47, 5076. ) an environmentally-friendly procedure for the amination of 1 to 2. Jens-Uwe Peters of Hoffmann-La Roche, Basel showed (Tetrahedron Lett. 2011, 52, 749. ) that the Udenfriend protocol could be used to convert drugs such as 3 to their hydroxylated metabolites. Suman L. Jain and Anil K. Sinha of the Indian Institute of Petroleum reported (Chem. Commun. 2011, 47, 1610. ) complementary conditions for arene hydroxylation.

Dimethyl aniline has been used, inter alia, as a nucleophile in enantioselective MacMillan conjugate addition. Zhong-Xia Wang of USTC established (Angew. Chem. Int. Ed. 2011, 50, 4901. ) that the quaternized salt 5 could participate in Negishi coupling. Mark R. Biscoe of the City College of New York discovered (Org. Lett. 2011, 13, 1218. ) that with a Ni catalyst, the secondary organozinc 9 will couple without rearrangement. Igor V. Alabugin of Florida State University devised (J. Org. Chem. 2011, 76, 1521. ) a radical-based protocol for replacing a phenolic OH with alkyl, to give 12. Petr Beier of the Academy of Sciences of the Czech Republic used (J. Org. Chem. 2011, 76, 4781. ) vicarious nucleophilic substitution followed by alkylation to convert 13 to 15.

Robin B. Bedford of the University of Bristol developed (Angew. Chem. Int. Ed. 2011, 50, 5524. ) a Pd-catalyzed procedure for the ortho bromination of an anilide 16. Jin-Quan Yu of Scripps/La Jolla took advantage (J. Am. Chem. Soc. 2011, 133, 7652. ) of the energetic N-O bond of 19 to drive the functionalization of 18 to 20.

Lei Liu of Tsinghua University devised (Org. Lett. 2011, 13, 3235. ) a Rh-mediated oxidative ortho coupling of the carbamate 21 with 22. Kohtaro Kirimura of Waseda University inserted (Chem. Lett. 2011, 40, 206. ) the DNA for a novel Trichosporon decarboxylase into E. coli, and found that the resulting fermentation efficiently converted 24 into 25. The alternative Kolbe-Schmitt reaction requires high temperature and pressure.

Sometimes, usually with more highly substituted benzene rings, it is worthwhile creating the ring. This can be done by oxidation of a cyclohexane derivative, as exemplified by the conversion of 26 to 27 reported (Science 2011, 333, 209. ) by Shannon S. Stahl of the University of Wisconsin. Or, it can be done by assembling the ring, as with the combination of 28 with 29 described (J. Org. Chem. 2011, 76, 1852. ) by Rick L. Danheiser of MIT. Stephen Y. W. Lau, working in the laboratory of the late Edward Piers at the University of British Columbia, assembled (Org. Lett. 2011, 13, 347. ) the skeleton of Hamigeran B (3) via the elegant condensation of 31 with 32.

D. F. Taber, Org. Chem. Highlights 2011, October 17.
URL: http://www.organic-chemistry.org/Highlights/2011/17October.shtm