Functional Group Interconversion: The Salom-Roig Synthesis of α-Conhydrine

Kwihwan Park, Tsuyoshi Yamada, and Hironao Sajiki of Gifu Pharmaceutical University devised conditions for the exchange of the allylic alcohol 1 with D₂O, to give the trideuterated allylic alcohol 2 (Org. Chem. Front. 2022, 9, 1986. DOI: 10.1039/D2QO00177B). Andrew R. Buller of the University of Wisconsin used an enzyme to effect the deuteration of the amino acid 3, leading to the dideuterated 4 (J. Am. Chem. Soc. 2022, 144, 7327. DOI: 10.1021/jacs.2c00608). Munetaka Kunishima of Kanazawa University alkylated the tertiary amine 5 with the triazene 6, then displaced the ammonium salt, leading to the bromide 7 (Tetrahedron Lett. 2022, 93, 153692. DOI: 10.1016/j.tetlet.2022.153692). Jiefeng Hu, Udo Radius and Todd B. Marder of the Julius-Maximilians-Universität Würzburg converted the sulfone 8 into the boronate 9 (Chem. Eur. J. 2022, 28, e202103866, DOI: 10.1002/chem.202103866; Chem. Commun. 2022, 58, 395, DOI: 10.1039/D1CC06144E).

Chi Zhang of Nankai University used the azidobenziodazolone 11 in conjunction with triphenylphosphine to convert the secondary alcohol 10 to the azide 11 with inversion of absolute configuration (Chem. Eur. J. 2022, 28, e202200272. DOI: 10.1002/chem.202200272). Jinbo Hu of the Shanghai Institute of Organic Chemistry described a parallel investigation (Nature Commun. 2022, 13, 2752. DOI: 10.1038/s41467-022-30132-x). Sabuj Kundu of the Indian Institute of Technology Kanpur used an Ir catalyst to convert the azide 13 into the tertiary amine 14 (J. Org. Chem. 2022, 87, 628. DOI: 10.1021/acs.joc.1c02625). William J. Kruper of Michigan State University Midland effected Ritter opening of the epoxide 15, leading to the protected amino alcohol 16 (J. Org. Chem. 2022, 87, 2063. DOI: 10.1021/acs.joc.1c01475). Peter R. Schreiner of Justus Liebig University established conditions for converting the tertiary alcohol 17 into the azide 18 (Org. Lett. 2022, 24, 1460. DOI: 10.1021/acs.orglett.2c00042).

Yusuke Kuroda of ITSUU Laboratory used a Pd catalyst to convert the imidate 19 into the allylic amide 20 (Synlett 2022, 33, 98. DOI: 10.1055/s-0041-1737140). Joshua P. Barham of the Universität Regensburg oxidized the tertiary amine 21 to the formamide 22 (Chem. Sci. 2022, 13, 1912. DOI: 10.1039/D1SC05840A). D. Christopher Braddock and Paul D. Lickiss of Imperial College London used the nontoxic methyltrimethoxysilane to mediate the coupling of the amine 24 with the carboxylic acid 23, leading to the amide 26 (Org. Lett. 2022, 24, 1175. DOI: 10.1021/acs.orglett.1c04265). Yujiro Hayashi of Tohoku University assembled the congested amide 29 by coupling the cysteine derivative 28 with the α-amidonitrile 27 (J. Am. Chem. Soc. 2022, 144, 10145. DOI: 10.1021/jacs.2c02993).

α-Conhydrine (32) is one of the poisonous alkaloids of hemlock, Conium maculatum. In the course of a synthesis of 32, Xavier J. Salom-Roig of the Université de Montpellier reduced the sulfoxide of 30 with t-butyl bromide, alkylated the resulting sulfide, and cyclized the sulfonium salt to the epoxide 31 (Eur. J. Org. Chem. 2022, e202101451. DOI: 10.1002/ejoc.202101451).