Alkyl nitrite-enabled palladium-catalyzed terminal selective oxidative cyclization of 4-penten-1-ols.

Oxidative cyclization of 4-penten-1-ols using a Pd catalyst and -BuONO or -BuONO/-benzoquinone afforded 3-hydroxy- and 3-methoxytetrahydropyrans terminal selective nucleophilic attack. The radicals formed from -BuONO and O operate as critical oxidants and ligands for Pd.

Synthesis of 2-hydroxytetrahydrofurans by Wacker-type oxidation of 1,1-disubstituted alkenes.

1,1-Disubstituted alkenes feature high steric hindrance, which renders their Wacker-type oxidation difficult. We demonstrate the stereoselective synthesis of 2-hydroxytetrahydrofurans the Wacker-type oxidation of 3-methyl-3-buten-1-ols by using a PdCl(MeCN)/NO/BQ catalyst system under 1 atm O in HO or HO/DMF.

Palladium-Catalyzed Aerobic Anti-Markovnikov Oxidation of Aliphatic Alkenes to Terminal Acetals.

Terminal acetals were selectively synthesized from various unbiased aliphatic terminal alkenes and 1,2-, 1,3-, or 1,4-diols using a PdCl(MeCN)/CuCl catalyst system in the presence of p-toluquinone under 1 atm of O and mild reaction conditions. The slow addition of terminal alkenes suppressed the isomerization to internal alkenes successfully. Electron-deficient cyclic alkenes, such as p-toluquinone, were key additives to enhance the catalytic activity and the anti-Markovnikov selectivity.