Oxidative Allylic Oxygenation and Amination

Sabine Laschat, Volker Rabe, and Angelika Baro 

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Oxidation of alcohols and amines. Allylic and benzylic alcohols can be oxidized to the aldehydes in high yield by oxygen in the presence of catalytic amounts of 1 and... 

The Cr-PILC catalyzed benzylic and allylic oxidations also provide a facile approach to the oxidative deprotection of allyl and benzyl ethers and amines. Treatment of allyl or benzyl ethers with one equivalent of tert-butyl hydroperoxide in the presence of Cr-PILC at room temperature resulted in the oxidative cleavage of the allyl- or benzyl-oxygen bond to give the alcohol but when two equivalents of tert-butyl hydroperoxide (TBHP) were used, the alcohol was oxidized further to the aldehyde or ketone (Eqn. 21.21).47 Oxidation of allyl amines resulted in the cleavage of the allyl-nitrogen bond to give the des-allyl amine.47 Benzyl amines, however, were oxidized to the benzamides (Eqn. 21.22).45... 

This reaction, which is related to the well-known amine oxide pyrolysis, involves a syn elimination of the selenenic acid, but proceeds under milder conditions (20 C to 60 C instead of 400 C). It is more regioselective, takes place away from the oxygen and leads to allyl alcohols instead of enols, except when the only available hydrogen is the one a to the hydroxy group (Scheme 173, b). ... 

Simple palladium(II) salts such as chloride and acetate efficiently catalyse aerobic oxidative A-alkylation of amines and amides with alcohols. This method is suitable for a variety of sulfonamides, amides, aromatic and heteroaromatic amines as well as benzylic and heterobenzylic alcohols with a low loadings of the catalyst (0.5-1 mol%) and the alcohols. A selective carbon-carbon double bond assisted o-C-H olefination is catalysed by palladium(II) acetate. The terminal oxidant is oxygen. Addition of TFA is essential for any meaningful yield. (PdOCOCF3)+ has been proposed as the active catalyst. The observed large difference in the inter- and intra-molecular KIE values implied that the coordination of the C=C bond occurs before C-H palladation in the catalytic cycle consequently, a mechanism involving the initial coordination of allylic C=C bond to (PdOCOCF3)+ followed by selective o-C-H bond metalation has... 

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