1557201-10-1Relevant articles and documents
Tosyloxybenziodoxolone: A Platform for Performing the Umpolung of Alkynes in One-Pot Transformations
Borrel, Julien,Waser, Jerome
supporting information, p. 142 - 146 (2021/12/27)
Ethynylbenziodoxolones (EBXs) are commonly encountered reagents for the electrophilic alkynylation of nucleophiles. Herein, we report a one-pot, two-step process for EBX generation and their direct application in substrate functionalization. Our approach enables us to bypass the originally mandatory isolation and purification of the reagents, resulting in a more efficient synthesis. We could apply this process to seven different transformations involving both two- and one-electron nucleophiles to obtain a large variety of alkynylated products.
Intermolecular Radical Addition to Ketoacids Enabled by Boron Activation
Xie, Shasha,Li, Defang,Huang, Hanchu,Zhang, Fuyuan,Chen, Yiyun
supporting information, p. 16237 - 16242 (2019/10/14)
The intermolecular radical addition to the carbonyl group is difficult due to the facile fragmentation of the resulting alkoxyl radical. To date, the intermolecular radical addition to ketones, a valuable approach to construct quaternary carbon centers, remains a formidable synthetic challenge. Here, we report the first visible-light-induced intermolecular alkyl boronic acid addition to α-ketoacids enabled by the Lewis acid activation. The in situ boron complex formation is confirmed by various spectroscopic measurements and mechanistic probing experiments, which facilitates various alkyl boronic acid addition to the carbonyl group and prevents the cleavage of the newly formed C-C bond. Diversely substituted lactates can be synthesized from readily available alkyl boronic acids and ketoacids at room temperature merely under visible light irradiation, without any additional reagent. This boron activation approach can be extended to alkyl dihydropyridines as radical precursors with external boron reagents for primary, secondary, and tertiary alkyl radical additions. The pharmaceutically useful anticholinergic precursors are easily scaled up in multigrams under metal-free conditions in flow reactors.
Visible-Light-Mediated Aerobic Oxidation of Organoboron Compounds Using in Situ Generated Hydrogen Peroxide
Weng, Wei-Zhi,Liang, Hao,Zhang, Bo
supporting information, p. 4979 - 4983 (2018/08/24)
A simple and general visible-light-mediated oxidation of organoboron compounds has been developed with rose bengal as the photocatalyst, substoichiometric Et3N as the electron donor, as well as air as the oxidant. This mild and metal-free protocol shows a broad substrate scope and provides a wide range of aliphatic alcohols and phenols in moderate to excellent yields. Notably, the robustness of this method is demonstrated on the stereospecific aerobic oxidation of organoboron compounds.
