- Development and comparison of the substrate scope of Pd-catalysts for the aerobic oxidation of alcohols
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(Chemical Equation Presented) Three catalysts for aerobic oxidation of alcohols are discussed and the effectiveness of each is evaluated for allylic, benzylic, aliphatic, and functionalized alcohols. Additionally, chiral nonracemic substrates as well as chemoselective and diastereoselective oxidations are investigated. In this study, the most convenient system for the Pd-catalyzed aerobic oxidation of alcohols is Pd(OAc)2 in combination with triethylamine. This system functions effectively for the majority of alcohols tested and uses mild conditions (3 to 5 mol % of catalyst, room temperature). Pd(IiPr)(OAc)2(H2O) (1) also successfully oxidizes the majority of alcohols evaluated. This system has the advantage of significantly lowering catalyst loadings but requires higher temperatures (0.1 to 1 mol % of catalyst, 60°C). A new catalyst is also disclosed, Pd(IiPr)(OPiv)2 (2). This catalyst operates under very mild conditions (1 mol %, room temperature, and air as the O2 source) but with a more limited substrate scope.
- Schultz, Mitchell J.,Hamilton, Steven S.,Jensen, David R.,Sigman, Matthew S.
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- Intramolecular Pd-Catalyzed Formal anti-Carboalkoxylation of Alkynes: Access to Tetrasubstituted Enol Ethers
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An intramolecular Pd-catalyzed formal anti-carboalkoxylation reaction is presented that provides access to tetrasubstituted enol ethers. The key to success is a cascade consisting of a formal anti-carbopalladation of a carbon–carbon triple bond followed by a nucleophilic attack of a hydroxy group at the emerging vinyl organopalladium species. The desired transformation proceeded smoothly with primary, secondary, and tertiary alcohols, and even with phenols. Depending on the substitution pattern of the enol ethers, a further Tsuji–Trost-type step may occur resulting in oligocyclic ketals.
- Schitter, Theresa,Jones, Peter G.,Werz, Daniel B.
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supporting information
p. 13446 - 13449
(2018/09/21)
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