An overview of the synthesis of acyl hydrazides from aldehydes and reactions of the products thereof

Abstract

Herein a review on the methods for the formation and reaction of acyl hydrazides will be given. There is particular focus on the synthesis of acyl hydrazides from aldehyde precursors with examination of the various approaches (e.g. metal-based (rhodium, copper) and non-metal-based (aerobically- and photoorganocatalytically-initiated)) that have been used to achieve this. Finally, strategies to utilise acyl hydrazides for the formation of an array of useful entities will be detailed.

1-(4-Fluorophenyl)-5-methyl-N′-{1-[5-methyl-1-(4-methylphenyl)-1H-1,2,3-triazol-4-yl]ethylidene}-1H-1,2,3-triazole-4-carbohydrazide

“…Acyl hydrazides are common precursors for the synthesis of various heterocycles and have a wide range of applications such as use in pharmaceuticals, as chemical preservatives for plants, and in the manufacture of polymers (Abdel-Wahab et al, 2017;Hassan & Shawky, 2010;Sarma et al, 2011;Shamsabadi & Chudasama, 2017).…”

Synthesis of novel heterocycles using 1,2,3‐triazole‐4‐carbohydrazides as precursors

“…In addition, these heterocycles act as herbicides and dyes . Acid hydrazides are generally produced from reaction of hydrazine and esters, cyclic anhydrides, acyl halides, and aldehydes, while [1,2,4]triazolo[3,4‐ b ][1,3,4]thiadiazines can be produced through a two‐step reaction that involves hydrazides, carbon disulfide, hydrazine hydrate, and phenacyl bromides …”

“…[21] In addition, these heterocycles act as herbicides [22] and dyes. [23,24] Acid hydrazides are generally produced from reaction of hydrazine and esters, cyclic anhydrides, acyl halides, and aldehydes, [25] while [1,2,4]triazolo [3,4-b] [1,3,4]thiadiazines can be produced through a two-step reaction that involves hydrazides, carbon disulfide, hydrazine hydrate, and phenacyl bromides. [26][27][28] Heterocycles such as 1,2,3-triazoles have potentially important applications, and various processes have been developed for their synthesis.…”

A facile route to 1H- and 2H-indazoles from readily accessible acyl hydrazides by exploiting a novel aryne-based molecular rearrangement

“…Recently our group 29,30 and others [31][32][33][34] have reported on acyl hydrazides as synthetically versatile scaffolds for the synthesis of a wide range of species. More specifically, acyl hydrazides have been employed in the creation of moieties such as amides, 35 esters, 35 thioesters, 35 ketones, 36 N-acyl carbamates 37 and 1,3,4-oxadiazoles, 38 as well as being used as building blocks for the creation of bioactive molecules such as hydroxamic acids 39 and macrocyclic enamides.…”