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Monday, May 20, 2019
Douglass F. Taber
University of Delaware

Oxidation: The Yao Synthesis of Plumisclerin A

Philippe Dauban of Gif-sur-Yvette used a Rh(II) carboxylate to catalyze the epoxidation of 1 to 2 (Eur. J. Org. Chem. 2018, 5836. ). Tobias Ritter of the Max-Planck-Institut für Kohlenforschung devised a scalable protocol for the photochemical decarboxylation of 3 to 4 (Nature Chem. 2018, 10, 1229. ). Vy M. Dong of the University of California, Irvine showed that a primary alcohol 5 in the presence of 6 could be converted to the alkene 7 (J. Am. Chem. Soc. 2018, 140, 10126. ). Hua-Li Qin of the Wuhan University of Technology oxidized and dehydrated the alcohol 8 to the alkyne 9 (J. Am. Chem. Soc. 2018, 140, 17666. ).

M. Bélen Cid of the Universidad Autónoma de Madrid oxidized the sulfone 10 to the aldehyde 11 (Org. Lett. 2018, 20, 5789. ). Alfredo Ballesteros of the Universidad de Oviedo converted the propargylic tosylate 12 to the iodo enone 13 (J. Org. Chem. 2018, 83, 12575. ). Jernej Iskra of the University of Ljubljana and Belén Martín-Matute of Stockholm University prepared the iodo ketone 15 from the allylic alcohol 14 (Adv. Synth. Catal. 2018, 360, 3884. ). Hiroki Tanimoto of the Nara Institute of Science and Technology showed that an α-azido ketone 16 could be converted to the α-diazo ketone 17 (J. Org. Chem. 2018, 83, 12103. ). Combining these two protocols, one could readily assemble both terminal and internal α-diazo ketones.

Rainer E. Martin of Hoffmann-La Roche and Robert Britton of Simon Fraser University devised a photochemical procedure for oxidizing an aldehyde 18 to the acyl fluoride 19 (Chem. Commun. 2018, 54, 9985. ). Guangbin Dong of the University of Chicago reported the conversion of the lactone 20 to the unsaturated lactone 21 (Angew. Chem. Int. Ed. 2018, 57, 16205. ). Yu-Long Zhao of Northeast Normal University effected the oxidative coupling of 22 with 23 in the presence of 24, leading to the amide 25 (Org. Lett. 2018, 20, 4862. ). K. N. Houk of UCLA and Manfred T. Reetz, also of the Max-Planck-Institut für Kohlenforschung, reported the directed evolution of an enzyme to catalyze the alternative Baeyer-Villiger conversion of the ketone 26 to the ester 27 (J. Am. Chem. Soc. 2018, 140, 10464. ).

In the course of a synthesis of plumisclerin A (31), Zhu-Jun Yao of Nanjing University needed to install the alkene regioselectively. The solution was to convert the aldehyde 28 with 29 to the separable mixture of diastereomeric selenides. Oxidation and syn elimination of the diastereomer 30 could only proceed in the desired direction. The undesired diastereomer was reduced back to 28 (Angew. Chem. Int. Ed. 2018, 57, 13313. ).

D. F. Taber, Org. Chem. Highlights 2019, May 20.
URL: https://www.organic-chemistry.org/Highlights/2019/20May.shtm