The Saegusa Oxidation and Related Procedures

Abstract

Palladium(II) Hydroxide and tert-Butyl Hydroperoxide, Oxygen, and a Base (Method F) ..

Synthetic Access to α-Oxoketene Aminals by the Nucleophilic Addition of Enol Silane-Derived Palladium(II) Enolates to Carbodiimides

“…In this case, the reaction did not provide the expected product 3t ; rather, cyclopent-2-en-1-one was obtained as the exclusive product. These results imply that palladium­(II) enolates derived from enol ethers with a β-hydrogen atom are susceptible to competitive Ito-Saegusa oxidation that preferentially delivers enone products via a β-hydride elimination process. − In the case of the enol silane 2u , in which the aryl moiety is replaced by an ester functionality as an α-substituent, we were able to observe the formation of the product 3u by TLC and LCMS ( m / z = 243.2 [M + + 1]). However, attempts to purify the crude material from 3u by column chromatography resulted in the decomposition of the product.…”

The Ligand Free Palladium(II)-Catalyzed Regioselective 1,2-Addition of Enol Silanes to Quinones to Access 4-Hydroxy-4-(2-oxo-2-arylethyl)cyclohexadien-1-ones and Synthetic Applications

“…The next experiment involved treatment of 1a (1 equiv) under standard conditions with a mixture of enol ethers 2a and 2r (0.65 equiv each) that differed by terminal Me substitution on the vinyl group (Scheme ; eqs 3 and 4). This reaction resulted in the formation of three products, the nucleophilic carbonyl addition product 3a in 43% yield, the Ito–Saegusa oxidation product 10a in 45% yield, and para -quinol 10b in 40% yield. − The formation of enone product 10a , which corroborates in situ generation of palladium enolate species from 2r and subsequent β-hydride elimination of the enolate, is conceptually compared with a similar metal enolate from 2a that undergoes intermolecular nucleophilic addition on the carbonyl group of the benzoquinone 1a . The chemoselective formation of the Ito–Saegusa oxidation product 10a over the Mukaiyama aldol product 3r from the silyl enol ether 2r in the presence of 1a indicates that the β-hydride elimination is a preferred pathway over nucleophilic addition, if the palladium enolate does possess a β-hydrogen atom.…”

The Reims Journey Towards Discovery and Understanding of Pd-Catalyzed Oxidations

“…A number of procedures are now available for the Pd-catalyzed dehydrogenation of carbonyl compounds [102]. Moreover, such a dehydrogenation may be a step of a domino reaction involving the Heck reaction, decarboxylative Heck reaction or dehydrogenative Heck reaction [103].…”