Borane evolution and its application to organic synthesis using the phase-vanishing method N. Soga, T. Yoshiki, A. Sato, T. Kawamoto, I. Ryu, H. Matsubara Tetrahedron Lett., 2021, 69, 13 pp. - DOI: 10.1016/j.tetlet.2021.152977
Although borane is a useful reagent, it is difficult to handle. In this study, borane was generated in situ from NaBH4 or nBu4NBH4 with several oxidants using a phase-vanishing (PV) method. The borane generated was directly reacted with alkenes, affording the desired alcohols in good yields after oxidation with H2O2 under basic conditions. The selective reduction of carboxylic acids with the evolved borane was examined. The organoboranes generated by the PV method successfully underwent Suzuki–Miyaura coupling. Using this PV system, reactions with borane can be carried out easily and safely in a common test tube.
Site-Selective Alkenylation of Unactivated C(sp3)-H Bonds Mediatedby Compact Sulfate Radical M. Ueda, K. Kamikawa, T. Fukuyama, Y.-T. Wang, Y.-K. Wu, I. Ryu Angew. Chem. Int . Ed., 2021, 60, 7 pp. 3545 - 3550 DOI: 10.1002/anie.202011992
A broad variety of unactivated acyclic and alicyclicsubstrates cleanly undergo site-selective alkenylation of unac-tivated C(sp3)-H bonds with 1,2-bis(phenylsulfonyl)ethene inthe presence of persulfate. This simple transformation fur-nishes (E)-2-alkylvinylphenylsulfones in up to 88 % yield. Incontrast with the previously reported decatungstate protocol,the current method is applicable to alkenylation of stericallyhindered C-H bonds. This important advantage significantlybroadens the substrate scope, and is attributed to the compactsize of the sulfate radical employed in the CH activation andcleavage.