C-O Ring Construction: The Hong Synthesis of Lasolonide A
Marco A. B. Ferreira of the Federal University of São Carlos cyclized 1 to the trans THF 2 (J. Org. Chem. 2018, 83, 7694. ). Ramesh Giri of the University of New Mexico assembled 4 by combining 3 with phenyl zinc iodide under Ni catalysis (J. Org. Chem. 2018, 83, 2920. ). Ruben Martin of ICIQ constructed the quaternary center of 7 by coupling 5 with 6 (J. Am. Chem. Soc. 2018, 140, 12200. ). Benjamin List of the Max-Planck-Institut für Kohlenforschung added 9 to 8 to give an intermediate that reacted stereoselectively with 10, leading to 11 (Angew. Chem. Int. Ed. 2018, 57, 12162. ).
Jongkook Lee of Kangwon National University cyclized 12 to the cis tetrahydropyran 13 (Org. Lett. 2018, 20, 6398. ). Shin-ichiro Shoda of Tohoku University showed that the unprotected glycoside 14 could be desulfurized to 15 (Tetrahedron Lett. 2018, 59, 3428. ). Gilles Dujardin of Le Mans University and Sylvain Collet of the University of Nantes added 17 to 16 to give 18. Coupling with the epimeric TMS ether delivered the alternative aryl diastereomer (Chem. Eur. J. 2018, 24, 14069. ). Vittorio Farina of Janssen Pharmaceutica and Eva Hevia of the University of Strathclyde developed a complementary strategy, preparing 20 by coupling 19 with diphenyl zinc (Angew. Chem. Int. Ed. 2018, 57, 10630. ).
Juan I. Padrón of the Instituto de Productos Naturales y Agrobiología (IPNA-CSIC) assembled 23 by coupling 21 with 22 (J. Org. Chem. 2018, 83, 12632. ). Li-Jin Xu of the Renmin University of China and Bi-Jie Li of Tsinghua University devised conditions for converting the terminal alkyne of 24 to the corresponding ketene, that cyclized to the macrolactone 25 (Org. Lett. 2018, 20, 6534. ). Hidefumi Makabe of Shinshu University completed the synthesis of altholactone 27 by the cyclocarbonylation of 26 (Tetrahedron Lett. 2018, 59, 4024. ). En route to divergolide E (not illustrated), Paul E. Floreancig of the University of Pittsburgh reduced the nitro arene 28 to the amine, that could be acylated in situ with 29, then cyclized to 30 (Angew. Chem. Int. Ed. 2018, 57, 15866. ).
Lasonolide A (33) shows potent anti-neoplastic activity. In the course of a total synthesis of 33, Ran Hong of the Shanghai Institute of Organic Chemistry cyclized the nitro alkene 31 to the dimethyl acetal 32 (Angew. Chem. Int. Ed. 2018, 57, 16200. ).