Wacker-Tsuji oxidation mechanism

The mechanism of the Wacker-Tsuji oxidation has been intensively investigated by both academia and industry and it is now very well elucidated. In the 2002 book Handbook of Orgamopalladium Chemistry for Organic Synthesis, edited by Ei-ichi Negishi, Ptrick M. 

The Pd(Quinox)Cl2, (Quinox = 2-(2-quinolyl)-4,5-dihydrooxazole) catalysed Wacker-type oxidation of olefins bearing homoallylic alcohols by TBHP led to the corresponding /3-hydroxy ketones in good yields. Since the oxidation was catalyst controlled, it was significantly faster than the substrate-controlled Tsuji-Wacker oxidation. The bis- and fra-homoallylic alcohols were oxidized to cyclic peroxyketals, presumably via nucleophilic attack of the methyl ketone. Kinetics of the Wacker-type oxidation of olefins by TBHP in the presence of Quinox (ligand), and (54) as the catalyst reveal first-order dependence on ligand and olefin, and rate saturation in TBHP, as expected of the proposed mechanism (Scheme 9)... 

Scheme 12.10 (a) Pd carbene-catalyzed Tsuji-Wacker oxidation of st5renes. (b) Proposed mechanism based on labelling experiments. 

One such example is shown in Scheme 9, where intermediate 20 was swiftiy taken to 37 in a one-pot deprotection-tosylation-intramolecular y-alkylation mechanism utilizing tosyl fluoride. The resulting terminal olefin, when subject to Tsuji-Wacker oxidation conditions, furnished methyl ketone 38, which when exposed to strongly basic conditions triggered the Robinson annulation sequence, providing us with a cyclopentenone annulated analog 39. 

---

See also in sourсe #XX -- [ , ]

---