Hydrazones carbonyl group derivatization

Derivatization of carbonyl groups (reduction or formation of N,N-dimethyl-hydrazones or oximes)... 

Several reagents for derivatization of carbonyl groups are also available. Dansylhydrazine reacts with carbonyl groups in the presence of trichloroacetic acid, yielding highly fluorescent dansylhydrazones that exhibit, however, limited stability. In addition, fluorescent hydrazones can be produced from carbonyl-containing compounds after their reaction with 4-hydrazino-2-oxa-l,3-diazole or... 

For decades oximes and hydrazones have been used for the derivatization of carbonyl compounds and are mainly applied for carbonyl group characterization in analytical procedures. However, they can also be applied as viable protecting groups in complex reaction schemes. For instance in the synthesis of ery-thronolide A a carbonyl group had to be converted to an oxime to allow the selective removal of the remaining isopropylidene protecting group without side reactions. The reconversion of the oxime to the carbonyl compound proceeds by A -nitrosation (Scheme 92). The previously attempted removal of the... 

Brp3 is also useful for transforming carbonyl groups to CF2 units. First, however, the carbonyl groups need to be derivatized to hydrazones or oxime ethers ... 

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