Acyl hydrazides as acyl donors for the synthesis of diaryl and aryl alkyl ketones

Abstract

In this communication we describe a novel strategy for the formation of valuable diaryl and aryl alkyl ketones from acyl hydrazides. A wide variety of ketones are prepared and the mild reaction conditions allow for the use of a range of functionalities, especially in the synthesis of diaryl ketones.

Acid Hydrazides

“…Thus, a mild and efficient protocol for ketone formation has been developed, which tolerates sensitive functional groups. 6 (C) 2-Amino-1,3,4-thiadiazoles have been efficiently synthesized utilizing TMSNCS and acid hydrazides as starting materials. The method involves in situ generation of thiosemicarbazides, which undergo acid-catalyzed cyclodehydration to give 2-amino-5-aryl-1,3,4-thiadiazoles.…”

“…Thus, they are used as effective acyl donors for the synthesis of ketones 6 and amides. 7 Acid hydrazides can be easily prepared by the combination of hydrazine with various acyl derivatives, including esters, cyclic anhydrides, and acyl halides.…”

A facile, one-pot procedure for the conversion of aromatic aldehydes to esters, as well as thioesters and amides, via acyl hydrazide intermediates

“…To do this, the aldehyde and azodicarboxylate were reacted in DMF at 21 °C for 24 h, followed by addition of alcohol and caesium carbonate and incubation at 21 °C for 16 h; reaction times were optimised by 19 F NMR studies. To our delight, after this two-step procedure, flash column chromatography afforded the desired ester in 74% isolated yield.…”

“…More recently, Chudasama, Caddick and co-workers have shown the formed acyl hydrazides to undergo reaction with Grignard reagents for the efficient synthesis of ketones. 19,21 With the acyl donor ability of acyl hydrazides in mind, we were intrigued by the possibility of using acyl hydrazides for the synthesis of esters. Moreover, with the stability of acyl hydrazides being well documented, we envisioned from the outset that such a development could be adapted to the one-pot conversion of aldehydes to esters via an in situ prepared acyl hydrazide intermediate ( Figure 1c).…”

“…[15][16][17][18][19][20][21][22][23][24][25][26] Moreover, the overall transformation has been shown to proceed under a wide range of reaction conditions, in a variety of solvents and with the aldehyde being employed as the limiting reagent. More recently, Chudasama, Caddick and co-workers have shown the formed acyl hydrazides to undergo reaction with Grignard reagents for the efficient synthesis of ketones.…”