Recovery of carbonyl compounds from N,N-dialkylhydrazones

Deprotonation of enantiomerically pure hydrazones and subsequent trapping w ith suitable electrophiles generates new stereogenic centers with excellent stereoselectivity. To liberate the original carbonyl functionality in the final products, it is necessary to cleave the hydrazone moiety. In recent y ears, many reagents have been developed to regenerate carbonyl compounds fr om the corresponding dialkylhydrazones which are compatible with a wide ran ge of functionalities. This has allowed the use of hydrazones in the total synthesis of complex natural products. This Account is meant to be an overv iew of methods which are classified as oxidative, hydrolytic, and reductive cleavage procedures.