C-H Functionalization: The Wei/Yang Synthesis of Cephalotine A

Ilan Marek of the Technion-Israel Institute of Technology showed that the mixture of alkenes from enzymatic oxidation of the alkane 1 could be converted into the terminal nitrile 2 by equilibrating hydrozirconation (Angew. Chem. Int. Ed. 2023, 62, e202306343. DOI: 10.1002/anie.202306343). Wanxiang Zhao of Hunan University described a parallel investigation based on halogenation followed by Co-catalyzed borylation (Angew. Chem. Int. Ed. 2023, 62, e202306248. DOI: 10.1002/anie.202306248). Steven L. Castle of Brigham Young University observed high regioselectivity in the conversion of the oxime ether 3 to the TEMPO ether 4 (J. Org. Chem. 2023, 88, 10287. DOI: 10.1021/acs.joc.3c00915).

Yan Xu of Peking University rearranged the cyanoacetate 5 to the nitrile 6 (Nature 2023, 620, 1007. DOI: 10.1038/s41586-023-06347-3). Lei Gong of Xiamen University assembled the sulfone 9 by coupling the acetate 7 with the allylic bromide 8 (Nature Synth. 2023, 2, 766. DOI: 10.1038/s44160-023-00291-w). Pinhong Chen of the Shanghai Institute of Organic Chemistry and Guosheng Liu of the University of Science and Technology of China effected enantioselective cyanation of the alkyne 10, leading to the nitrile 11 (Chem. Commun. 2023, 59, 4656. DOI: 10.1039/D3CC00410D). Pu-Sheng Wang, Xin Hong and Liu-Zhu Gong, also of the University of Science and Technology, constructed the quaternary center of 14 by the Pd-mediated oxidative coupling of the alkene 12 with the α-benzothiazylacetamide 13 (Angew. Chem. Int. Ed. 2023, 62, e202312547. DOI: 10.1002/anie.202312547).

Durga Prasad Hari of the Indian Institute of Science Bangalore cyclized the α-diazo ester 15 to the β-lactone 16 (Org. Lett. 2023, 25, 4974. DOI: 10.1021/acs.orglett.3c01549). Jin-Quan Yu of Scripps/La Jolla assembled the γ-lactone 19 by the oxidative coupling of the carboxylic acid 17 with the aryl iodide 18 (Angew. Chem. Int. Ed. 2023, 62, e202312331. DOI: 10.1002/anie.202312331). Sukbok Chang of the Korea Advanced Institute of Science and Techology used a Cu catalyst to effect the enantioselective cyclization of the dioxazolone 20 to the δ-lactam 21 (J. Am. Chem. Soc. 2023, 145, 16238. DOI: 10.1021/jacs.3c05258). Jin-Bao Peng of Wuyi University used a Pd catalyst to mediate the enantioselective cyclization of the prochiral cyclopropane 22 to the highly substituted cyclopropane 23 (Chem. Sci. 2023, 14, 7564. DOI: 10.1039/D3SC02168H).

Richiro Ushimaru and Ikuro Abe of the University of Tokyo, Yisong Guo of Carnegie Mellon University and Wei-chen Chang of North Carolina State University delineated the mechnism of the enzymatic conversion of the ε-nitro α-amino acid 24 to the cyclopropane 25 (J. Am. Chem. Soc. 2023, 145, 24210. DOI: 10.1021/jacs.3c08413). David E. Olson of the University of California, Davis used a Rh catalyst to cyclize the α-diazo ester derived from the α-keto ester 26 to the β-amino ester 27 (J. Org. Chem. 2023, 88, 13712. DOI: 10.1021/acs.joc.3c01363).

Cephalotine A (30) was isolated from the coniferous tree Cephalotaxus lanceolata of northern Myanmar and southern China. Kun Wei and Yu-Rong Yang of the Kunming Institute of Botany established the central quaternary center of 30 by the cyclization of the dioxazolone 28 to the γ-lactam 29 (Org. Lett. 2023, 25, 7459. DOI: 10.1021/acs.orglett.3c02097).