C-H Functionalization: The Borhan Synthesis of Salinosporamide A
Jieping Zhu of the École Polytechnique Fédérale de Lausanne delivered azide specifically to the methine of 1, leading to 2 (Chem. Eur. J. 2019, 25, 9477. ). Erik J. Alexanian of the University of North Carolina also observed high selectivity in the chlorination of 3 with 4 to give 5 (J. Org. Chem. 2019, 84, 12983. ).
Xin-Hua Duan of Xi'an Jiaotong University assembled the nitrile 8 by adding the methine radical derived from 6 to 7 (Org. Lett. 2019, 21, 5500. ). Jennifer L. Roizen of Duke University (Org. Lett. 2019, 21, 6089. ) and Wei Shu of the Southern University of Science and Technology (Org. Lett. 2019, 21, 6107. ) also found sulfamates to be effective for remote functionalization. Uttam K. Tambar of the University of Texas Southwest Medical Center developed a protocol for preparing the branched coupled product 10 from 9 (J. Am. Chem. Soc. 2019, 141, 17305. ). Pu-Sheng Wang and Liu-Zhu Gong of the University of Science and Technology of China devised a procedure (not illustrated) leading to the complementary linear product (Org. Lett. 2019, 21, 6720. ).
Hidetoshi Noda and Masakatsu Shibasaki of the Institute of Microbial Chemistry cyclized 11 to 12 (Org. Lett. 2019, 21, 9296. ). The late Kilian Muńiz of ICIQ prepared the pyrrolidine 14 by the double functionalization of 13 (Angew. Chem. Int. Ed. 2019, 58, 7485. ). Seiji Iwasa of the Toyohashi University of Technology achieved high enantioselectivity in the cyclization of 15 to the γ-lactam 16 (J. Org. Chem. 2019, 84, 2607. ). Wenhao Hu of Sun Yat-sen University and Xinfang Xu of Soochow University prepared the macrocycle 18 by the Rh-mediated cyclization of 17 (ACS Catal. 2019, 9, 10773. ).
Alberto Hernán-Gómez and Miquel Costas of the Universitat de Girona devised an iron catalyst that mediated the cyclization of 19 to the cyclopentane 20 (Angew. Chem. Int. Ed. 2019, 58, 13904. ). Tomoya Miura and Masahiro Murakami of Kyoto University showed that the triazole 21 could be cyclized to the imine 22 (Chem. Lett. 2019, 48, 510. ). Susumu Ohira of the Okayama University of Science developed a new diol protecting group to enable the cyclization of 23 to 24 (Tetrahedron Lett. 2019, 60, 151085. ). Olivier Baudoin of the University of Basel used a Pd catalyst to cyclize 25 to the indane 26 (J. Org. Chem. 2019, 84, 12933. ).
Salinosporamide A (29), isolated from the marine bacterium Salinispora tropica, shows significant anti-cancer activity. In the course of a synthesis of 29, Babak Borhan of Michigan State University cyclized 27 to 28 (Angew. Chem. Int. Ed. 2019, 58, 10110. ).