Catalytic Oxidation of Alkynes into 1,2‐Diketone Derivatives by Using a Pd II /Lewis‐Acid Catalyst

• Published in: Asian journal of organic chemistry 2018-01, Vol.7 (1), p.212-219
• Main Authors: Xue, Jing‐Wen, Zeng, Miao, Hou, Xianfei, Chen, Zhuqi, Yin, Guochuan
• Format: Article
• Language: English
• ISSN: 2193-5807; 2193-5815
• DOI: 10.1002/ajoc.201700556

A new synthetic method has been developed for the efficient oxidation of alkynes into 1,2‐diketones by using a Pd II /Lewis acid catalytic system using DMSO as the oxidant and solvent. Under our optimized reaction conditions, this approach tolerated a variety of functional groups and afforded 1,2‐diketone derivatives in 62–99 % yields. This work demonstrated that the addition of non‐redox‐active metal ions, such as Al III , to Pd(OAc) 2 could dramatically improve its catalytic efficiency for alkyne oxidation, whilst reactions with Pd(OAc) 2 alone were sluggish and afforded a low yield of the corresponding diketone. Based on NMR and UV/Vis analysis, a heterobimetallic Pd II /Al III species was proposed for alkyne oxidation by adding AlCl 3 to Pd(OAc) 2 in DMSO. The catalytic efficiency of the Pd II species was improved by the linkage of Al III to the Pd II species, which made the Pd II species more electron deficient. This method may have the potential to become a simple, efficient procedure for the synthesis of 1,2‐diketone derivatives.