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Monday, June 15, 2015
Douglass F. Taber
University of Delaware

Substituted Benzenes: The Li Synthesis of Rubriflordilactone A

Cheol-Hong Cheon of Korea University (J. Org. Chem. 2014, 79, 7277. ) and Toshiyuki Kamei and Toyoshi Shimada of the Nara National College of Technology (Tetrahedron Lett. 2014, 55, 4245. ) described the ring bromination of arene boronates. The boronate can then be removed, enabling the conversion of 1 to 2. Yu Rao of Tsinghua University constructed (Chem. Commun. 2014, 50, 15037. ) the sulfone 5 by coupling the arenes 3 and 4 with K2S2O8.

Igor Larrosa of Queen Mary University of London assembled (Chem. Sci. 2014, 5, 3509. ) the biphenyl 8 by arylating 6 with the iodide 7. Guy Bertrand of the University of California, San Diego showed (J. Am. Chem. Soc. 2014, 136, 13594. ) that under Au catalysis, the aniline 9 was sufficiently nucleophilic to add in a conjugate sense to the enone 10 to give 11.

Hideo Togo of Chiba University optimized (Eur. J. Org. Chem. 2014, 6077. ) conditions for the selective ortho formylation of a phenol 12. The crude reaction mixture could also be directly oxidized with I2/NH3 to give the nitrile 13. Silas P. Cook of Indiana University ortho metalated (J. Am. Chem. Soc. 2014, 136, 13130, ; Angew. Chem. Int. Ed. 2014, 53, 11065, ) the benzamide 14, then used an iron catalyst to couple that intermediate with a halide 15, leading to the alkylated product 16.

As with the phenol 12 and the benzamide 14, aromatic functionalization has usually been directed by a functional group directly attached to the ring. Daqin Shi and Yingsheng Zhao of Soochow University showed (Chem. Sci. 2014, 5, 4962. ) that a longer tether can be effective, as illustrated by the conversion of 17 to 19. Debabrata Maiti of the Indian Institute of Technology Bombay also used (Org. Lett. 2014, 16, 5760. ) a longer tether for the selective meta functionalization of 20 to 22.

Motohiro Sonoda of Osaka Prefecture University constructed (Tetrahedron Lett. 2014, 55, 5302. ) the phenol 25 by acid-mediated rearrangement of the Diels-Alder adduct of 24 with the furan 23. Anthony G. M. Barrett of Imperial College London devised (J. Org. Chem. 2014, 79, 8706. ) conditions for the iodinative cyclization of 26 to 27. Katsukiyo Miura of Saitama University found (Org. Lett. 2014, 16, 4762. ) that hydroalumination cyclized 28 to 29. P. Andrew Evans of Queens University observed (Org. Lett. 2014, 16, 4356. ) high regioselectivity in the cyclization of 30 to 31. Young Keun Chung of Seoul National University reported (Org. Lett. 2014, 16, 4352. ) a similar cyclocarbonylation (not illustrated).

Extracts of the magnolia vine Schisandra rubriflora have been widely used in Chinese herbal medicine. En route to Rubriflordilactone A (34), Ang Li of the Shanghai Institute of Organic Chemistry assembled (J. Am. Chem. Soc. 2014, 136, 16477. ) the enantiomerically-pure triene 32, that on warming in the presence of air cyclized to 33.

D. F. Taber, Org. Chem. Highlights 2015, June 15.
URL: https://www.organic-chemistry.org/Highlights/2015/15June.shtm