Pd-Catalyzed TBHP-Mediated Selective Wacker-Type Oxidation and Oxo-acyloxylation of Olefins Using a 2‑(1H‑Indazol-1-yl)quinoline Ligand

• Published in: Organic letters 2023-03, Vol.25 (11), p.1850-1855
• Main Authors: Zhang, Shuaizhong, Zhang, Jinquan, Zou, Hongbin
• Format: Article
• Language: English
• ISSN: 1523-7060; 1523-7052
• DOI: 10.1021/acs.orglett.3c00326

Pd­(II)-catalyzed oxidation of terminal olefins to methyl ketones has emerged as an attractive strategy for organic synthesis. Here we report the Pd­(II)-catalyzed selective oxidation of olefins using tert-butyl hydroperoxide as the oxidant and 2-(1H-indazol-1-yl)­quinoline as the ligand. A wide range of olefins were well tolerated in this reaction system to provide methyl ketones, whereas the presence of Ac2O initiated the oxo-acyloxylation to afford the α-acetoxyacetone products. Isotope labeling studies and active-intermediate-capture experiments were performed to elucidate the underlying selective reaction mechanism. Notably, the generation of α-acetoxyacetone products involves the palladium enolate intermediate while the methyl ketone products were generated through the most commonly proposed alkylperoxide intermediates, followed by 1,2-hydride migration.