C-H Functionalization: The Baran Synthesis of Maximiscine
Jie Wu of Taizhou University prepared the vinyl sulfone 3 by coupling the tertiary propargylic alcohol 1 with the diazonium salt 2 in the presence of sodium metabisulfite (Adv. Synth. Catal. 2020, 362, 4744. ). Mu-Hyun Baik and Soon Hyeok Hong of KAIST observed high selectivity for the 1,4-diketone 6 from the acylation of the ketone 4 wth the succinylamide 5 (Angew. Chem. Int. Ed. 2020, 59, 16933. ).
David B. C. Martin of the University of Iowa achieved high diastereoselectivity in the coupling of 7 with 8, leading to the sulfinylamide 9 (Chem. Commun. 2020, 56, 9699. ). Huw M. L. Davies of Emory University and Christopher W. Jones of the Georgia Institute of Technology designed a Rh catalyst that worked well in flow for the diastereoselective and enantioselective coupling of the diazo ester 11 with just one of the 16 C-H bonds of 10 (Angew. Chem. Int. Ed. 2020, 59, 19525. ).
Sukbok Chang, also of KAIST, cyclized the 1,4-2-dioxol-5-one to the γ-lactam 14 (J. Am. Chem. Soc. 2020, 142, 8880. ). Bing-Feng Shi of Zhejiang University assembled the γ-lactam 17 by coupling the amide 15 with the alkenyl iodide 16 (Angew. Chem. Int. Ed. 2020, 59, 14060. ). Donovon Adpressa and Charles S. Yeung of Merck and Richmond Sarpong of the University of California, Berkeley cyclized the sulfonamide 18 to the pyrrolidine 19 (Org. Lett. 2020, 22, 6578. ). Chi-Ming Che of the University of Hong Kong used visible light to promote the Fe-catalyzed cyclization of the α-azido ketone 20 to the pyrrolidine 21 (Chem. Sci. 2020, 11, 4680. ).
Olivier Baudoin of the University of Basel used the proximal bromo arene to oxidize the γ-lactone 22 to the cyclopropane 23 (J. Am. Chem. Soc. 2020, 142, 15355. ). Yuxue Li of the Shanghai Institute of Organic Chemistry and Liming Zhang of the University of California, Santa Barbara employed a gold catalyst to cyclize the alkynyl ketone 24 to the α-benzoyl cyclobutanone 25 (Angew. Chem. Int. Ed. 2020, 59, 17398. ). Hosea M. Nelson of UCLA used a urea catalyst to cyclize the alkenyl triflate 26 to the cyclopentene 27 (Org. Lett. 2020, 22, 7775. ). Keiji Mori of the Tokyo University of Agriculture and Technology showed that a Lewis acid was sufficient to cyclize the dienyl diester 28 to the cyclohexane 29 (Org. Lett. 2020, 22, 5801. ).
Maximiscin (32), an antibiotic derived from an Alaskan soil sample, showed significant anti-cancer activity. En route to 32, Phil S. Baran of Scripps/La Jolla achieved high diastereoselectivity in the oxidation of 30 to 31 (J. Am. Chem. Soc. 2020, 142, 8608. ).