Organic Chemistry Portal
Organic Chemistry Highlights

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. DOI: 10.1021/jo500780b) and Toshiyuki Kamei and Toyoshi Shimada of the Nara National College of Technology (Tetrahedron Lett. 2014, 55, 4245. DOI: 10.1016/j.tetlet.2014.06.003) 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. DOI: 10.1039/C4CC05964F ) 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. DOI: 10.1039/C4SC01215A) 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. DOI: 10.1021/ja507788r) 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. DOI: 10.1002/ejoc.201402817) 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, DOI: 10.1021/ja506823u; Angew. Chem. Int. Ed. 2014, 53, 11065, DOI: 10.1002/anie.201406594) 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. DOI: 10.1039/C4SC02172J) 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. DOI: 10.1021/ol502823c) a longer tether for the selective meta functionalization of 20 to 22.

Motohiro Sonoda of Osaka Prefecture University constructed (Tetrahedron Lett. 2014, 55, 5302. DOI: 10.1016/j.tetlet.2014.07.084) 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. DOI: 10.1021/jo5015068) conditions for the iodinative cyclization of 26 to 27. Katsukiyo Miura of Saitama University found (Org. Lett. 2014, 16, 4762. DOI: 10.1021/ol5022096) that hydroalumination cyclized 28 to 29. P. Andrew Evans of Queens University observed (Org. Lett. 2014, 16, 4356. DOI: 10.1021/ol501724s) high regioselectivity in the cyclization of 30 to 31. Young Keun Chung of Seoul National University reported (Org. Lett. 2014, 16, 4352. DOI: 10.1021/ol5015224) 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. DOI: 10.1021/ja5092563) 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.