Reactions of Hydrazones with Lead Tetraacetate in Organic Synthesis

The progress that has been made in organic synthesis via the reactions of hydrazones with lead tetraacetate, mainly since 1970, is presented in this review. Thus, the synthesis of various compounds, as gem-azoacetates, azo and diazo compounds, acylhydrazines, alkenes, oxadiazolines, triazoles, pyrazoles, indazoles and dibenzazepinones will be discussed. Special emphasis is given in a synthetically useful new rearrangement that takes place in LTA oxidations of N-acylhydrazones of ohydroxyaryl ketones and leads to high yield synthesis of 1,2-diacylbenzenes, oacylarylcarboxylic esters, o-acylbenzoyl bromides, 1,2,3- triacylbenzenes, 1,2,3,4- tetraacylbenzenes, o-acylbenzaldehydes and o-phthalaldehyde. Finally, some of the applications of hydrazones and their derivatives are discussed.