Aldehydes common reaction theme

What Is the Most Common Reaction Theme of Aldehydes and Ketones ... 

The common reaction theme of the carbonyl group of aldehydes and ketones is the addition of a nucleophile to form a tetrahedral carbonyl addition intermediate. 

The most common reaction theme of acid halides, anhydrides, esters, and amides is the addition of a nucleophile to the carbonyl carbon to form a tetrahedral carbonyl addition intermediate. To this extent, the reactions of these functional groups are similar to nucleophilic addition to the carbonyl groups in aldehydes and ketones (Section 12.4). The tetrahedral carbonyl addition intermediate (TCAI) formed from an aldehyde or a ketone then adds H". The result of this reaction is nucleophilic addition to a carbonyl group of an aldehyde or a ketone ... 

Direct IV-oxidation of these heterocycles invariably fails (see Section 3.02.7.2.8), making ring synthetic methods the only viable alternative <93CHE127>. Although there has been considerable interest in the chemistry of compounds of this type, there are no new synthetic approaches of a general nature. The most common approach is to react a-oximinoketones with aldehydes and primary amines. With formaldehyde, however, the 2-unsubstituted 1-oxides rearrange to 2-imi-dazolones. Variations on this theme allow synthesis of 1-hydroxyimidazole 3-oxides. Thus, treatment of an a-dicarbonyl compound with an aldehyde and hydroxylamine, or reaction of the aldehyde oxime or aldehyde with a 1,2-dioxime are common approaches <898773 >. Similarly, a-hydroxyamino-... 

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