Oxidation of alcohols using an oxoammonium salt bearing the nitrate anion

Solvent- and additive-free oxidative amidation of aldehydes using a recyclable oxoammonium salt

“…What differentiates 6 from other oxoammonium salts is that it can be used at a substoichiometric level for the oxidation of alcohols to aldehydes and ketones. 22 Indeed, 0.5 eq. of 6 can be used as the sole oxidant, in the presence of a small quantity of silica gel as an additive.…”

“…26,27 There is precedent for this in the oxidation of alcohols to aldehydes and ketones. 28 Nitric acid has been used to oxidise benzylic alcohols to carbonyl compounds in the absence of additional reagents. 29 Depending on the conditions used, either the nitrite ion, [NO 2 ] − , or nitrogen dioxide, NO 2 , is proposed as the key oxidising species.…”

Oxidation of Alcohols to Aldehydes and Ketones Using a Catalytic Pairing of a Nitroxide and Nitric Acid

“…In 4 , the nitrate counterion is not innocent and instead plays a role in the reaction mechanism. 7 9 This is not totally unexpected. There is precedent for the oxidation of alcohols in a catalytic manner using nitroxides in the presence of nitrogen oxide (NO x ) co-catalysts, with oxygen being the terminal oxidant (Scheme 1c–e ).…”

“…6 When employing 4 , the nitrate anion analogue of 1 , it is possible to oxidize alcohols to the corresponding carbonyl compounds very effectively. 7 8 9 These transformations can be performed using 0.5–0.6 equiv of 4 and the substrate scope proves to be quite broad. The reactions can be performed in solvent with silica gel as an additive (Scheme 1a ) 9 or under solvent-free or mechanochemical conditions without the need for additives (Scheme 1b ).…”

“…In order to optimize reaction conditions for the oxidation of alcohols to aldehydes and ketones, we decided to use 1-octanol ( 5a ) as a model substrate. As a starting point, we chose reaction conditions similar to those employed in our other oxidative transformations using 4 , 7 9 but this time starting with 3 . We chose to use 2 mmol of the alcohol substrate, 0.3 equiv of 3 , in 2 mL of dichloromethane, and heating the reaction mixture at 55 °C for 3 h. With the addition of 0.4 equiv of nitric acid, we observed a 69% conversion into 1-octanal ( 6a ) along with 12% of the nitroso intermediate ( 7a ) and 8% of octanoic acid ( 8a , Table 1 , entry 1).…”