Peroxides acyl, with aldehydes

Condensation with Aldehydes and Ketones. Succinic anhydride and succinic esters in the presence of different catalysts react in the gas phase with formaldehyde to give citraconic acid or anhydride and itaconic acid (94—96). Dialkyl acyl succinates are obtained by reaction of dialkyl succinates with C 4 aldehydes over peroxide catalysts (97). 

Similar additions have been successfully carried out with carboxylic acids, anhydrides, acyl halides, carboxylic esters, nitriles, and other types of compounds. These reactions are not successful when the alkene contains electron-withdrawing groups such as halo or carbonyl groups. A free-radical initiator is required, usually peroxides or UV light. The mechanism is illustrated for aldehydes but is similar for the other compounds ... 

Another peculiarity of the aldehyde oxidation is connected with the chemistry of the primary molecular product of oxidation, acyl peracid. The formed peracid interacts with the aldehydes to form peroxide with the structure RC(0)OOCH(OH)R [4,5]. This peroxide is unstable and decomposes into acids and free radicals. 

Reduction of carboxylic acids 9-42 Reduction of carboxylic esters 9-43 Reduction of carboxylic esters with titanocene dichloride 9-44 Reduction of anhydrides 9-45 Reduction of acyl halides 9-53 Reduction of nitriles 9-57 Reduction of hydroperoxides 9-60 Reduction of peroxides 9-69 Reaction between aldehydes and base (Cannizzaro)... 

Peracids can also be prepared from reaction of hydrogen peroxide with acyl halides, anhydrides, amides, dialkyl phosphates, N-acylimidazoles, aromatic aldehydes, lipase catalysis and esters (Figure 2.38).100-107... 

Conversion to Thioesters. The transformation of A7-acyl imides into thioesters with lithium thiolate reagents proceeds with exceptional selectivity for the exo carbonyl moiety even in exceptionally hindered cases. A recent application of this reaction in a complex setting has been reported (eq 66). This transformation is significant in that the normally reliable peroxide hydrolysis procedure proved to be nonselective. The recently reported high yield reduction of thioesters to aldehydes enhances the utility of these thioester intermediates. 

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