Organic Chemistry Portal
Organic Chemistry Highlights

Monday, February 26, 2024
Douglass F. Taber
University of Delaware

Arrays of Stereogenic Centers: The Wei/Yang Synthesis of Cephalotaxine

Joshua D. Sieber of Virginia Commonwealth University used a Cu catalyst to mediate the assembly of the protected amino alcohol 3 by the addition of the allenamide 2 to the aldehyde 1 (Org. Lett. 2023, 25, 4644, DOI: 10.1021/acs.orglett.3c01459; 4730, DOI: 10.1021/acs.orglett.3c01698) Yoshiyasu Ichikawa of Kochi University used an allyl cyanate to isocyanate rearrangement to convert the carbamate 4 to the oxazolidinone 5 (Heterocycles 2023, 106, 649. DOI: 10.3987/COM-23-14817). Xin Hong of Zhejiang University and Qiang-Shuai Gu and Xin-Luan Liu of the Southern University of Science and Technology effected enantioselective derivitization of the prochiral triol 6, leading to the sulfonate 7 (Nature Chem. 2023, 15, 395. DOI: 10.1038/s41557-022-01102-z). Robert M. Waymouth of Stanford University selectively oxidized the sugar derivative 8 to the ketone 9 (J. Am. Chem. Soc. 2023, 145, 2282. DOI: 10.1021/jacs.2c10667).

Zhi-Tao He of the Shanghai Institute of Organic Chemistry used a synergistic combination of a Pd catalyst and a Cinchona-derived amino alcohol to assemble the dihydrofuran 12 by coupling ethyl sorbate (10) with the β-keto ester 11 (Angew. Chem. Int. Ed. 2023, 62, e202215568. DOI: 10.1002/anie.202215568). Pere Clapés of the Institute for Advanced Chemistry of Catalonia used an enzyme-mediated formaldehyde aldol reaction followed by an enzymatic reduction to convert the α-keto acid 13 into the lactone 14 (ACS Catal. 2023, 13, 5348. DOI: 10.1021/acscatal.3c00367). Shinji Nagumo of Kogakuin University observed high diastereocontrol in the reduction of the epoxy diene 15 to the allylic alcohol 16 (Chem. Asian J. 2022, 17, e202200650. DOI: 10.1002/asia.202200650). Li Rao and Liang-Qiu Lu of Central China Normal University prepared the tetrahydrofuran 19 by irradiating the diazo ketone 18 in the presence of the activated cyclopropane 17 (Angew. Chem. Int. Ed. 2023, 62, e202212444. DOI: 10.1002/anie.202212444).

Takeyuki Suzuki of Osaka University developed the enantioselective Tishchenko transformation of the prochiral dialdehyde 20 to the lactone 21 (Tetrahedron 2023, 133, 133287. DOI: 10.1016/j.tet.2023.133287). Alexander J. Grenning of the University of Florida constructed the diene 24 by coupling the dinitrile 23 with the allylic carbonate 22, followed by Cope rearrangement (Chem. Sci. 2023, 14, 2755. DOI: 10.1039/D2SC07021A). Jingxiang Pang, Aiqin Liu and Zhushuang Bai of the Shandong First Medical University used the Hayashi-Jørgensen catalyst to mediate the conjugate addition of the aldehyde 26 to the unsaturated lactone 25, then isolated the product as the tosylhydrazone 27 (Org. Chem. Front. 2023, 10, 1527. DOI: 10.1039/D2QO01891H). Armen Zakarian of the University of California, Santa Barbara showed that using a lithiated diamine as base, the Ireland-Claisen rearrangement of the allylic ester 28 delivered the rearranged acid 29 with high diastereoselectivity (J. Org. Chem. 2023, 88, 7560. DOI: 10.1021/acs.joc.3c00535).

Cephalotaxine (33) was isolated from the Japanese plum yew Cephalotaxus drupacea. The esters of 33 show important anti-cancer activity. Building on the results of Wang and of Zhang (Arrays of Stereogenic Centers: The Knochel Synthesis of Siphonarienal 2019, February 25.), Kun Wei and Yu-Rong Yang of the Kunming Institute of Botany coupled the protected amino ester 31 with the allylic carbonate 30, leading to 31, having two of the three stereogenic centers of 33 (Org. Chem. Front. 2023, 10, 2532. DOI: 10.1039/D2OB00486K).

We note that the journal Heterocycles suspended publication at the end of 2023. We appreciate the dedication of the editors in keeping this journal going for so many years.

D. F. Taber, Org. Chem. Highlights 2024, February 26.