Oxidation: The Zhu Synthesis of Cepharamine
Oleg V. Larionov of the University of Texas at San Antonio used an acridine photocatalyst to mediate the decarboxylative conversion of the carboxylic acid 1 to the sulfonamide 2 (Chem. Sci. 2021, 12, 6429. DOI: 10.1039/D1SC01389K). Zacharias Amara of Cnam, HESAM Université and Janine Cossy of ESPCI Paris optimized the selective oxidation of amorphadiene 3 to the allylic alcohol 4 (J. Org. Chem. 2021, 86, 7603. DOI: 10.1021/acs.joc.1c00653).
Hongjian Lu of Nanjing University devised the oxidative decarboxylation of the carboxylic acid 5 to the protected amine 6 (Angew. Chem. Int. Ed. 2021, 60, 1845. DOI: 10.1002/anie.202010974). Bill Morandi of ETH Zürich used a Ru catalyst to oxidize the tertiary amine 7 to the enamine 8 (Angew. Chem. Int. Ed. 2021, 60, 7290. DOI: 10.1002/anie.202015837). Ho-Hsuan Chou of the National Cheng Kung University developed the reagent 10 to directly convert the α-amino amide 9 to the α-diazo amide 11 (Chem. Commun. 2021, 57, 4839. DOI: 10.1039/D1CC01285A). Ronald Micura of the University of Innsbruck showed that the reagent 13 could convert RNA 12 bearing an α-amino amide to RNA 14 bearing an α-azido amide (Angew. Chem. Int. Ed. 2021, 60, 6970. DOI: 10.1002/anie.202015034).
Yunhai Tao of Yunnan University found that octadecanethiol mediated the oxidation of the enol ether 15 to the unsaturated aldehyde 16 (J. Org. Chem. 2021, 86, 5463. DOI: 10.1021/acs.joc.0c02987). Phil S. Baran of Scripps/La Jolla showed that a silyl enol ether 17 could be converted by electrolysis to the α,β-unsaturated ketone 18 (Nature Chem. 2021, 13, 367. DOI: 10.1038/s41557-021-00640-2). Guangbin Dong of the University of Chicago observed high regioselectivity in the direct oxidation of the ketone 19 to the α,β-unsaturated ketone 20 (Angew. Chem. Int. Ed. 2021, 60, 7956. DOI: 10.1002/anie.202013628). Alexander O. Terent'ev of the N. D. Zelinsky Institute of Organic Chemistry also achieved high regioselectivity in the coupling of the ketal 21 with the reagent 22, leading to the ester 23 (Org. Chem. Front. 2021, 8, 3091. DOI: 10.1039/D1QO00494H).
Ning Jiao of Peking University showed that a catalytic N-heterocyclic carbene could mediate the oxidation of the benzylic bromide 24 to the ester 25 (Angew. Chem. Int. Ed. 2021, 60, 2140. DOI: 10.1002/anie.202011039). Sushil K. Maurya of CSIR-Institute of Himalayan Bioresource Technology used a reusable vanadium catalyst to oxidize olive oil and also non-edible vegetable oils to azelaic acid (26) (Chem. Commun. 2021, 57, 5430. DOI: 10.1039/D1CC01742J).
The alkaloid cepharamine (30) was isolated from the Korean succulent Stephania cepharantha. In the course of a synthesis of 30, Jieping Zhu of the Ecole Polytechnique Fédérale de Lausanne observed high regioselectivity in the assembly of the thioketal 29 by the coupling of the ketone 27 with the reagent 28 (Nature Commun. 2021, 12, 36. DOI: 10.1038/s41467-020-20274-1).