Reactions of hydrazides and hydrazones with n-butyl-lithium

Five‐Membered Heterocycles: 1,2‐Azoles. Part 1. Pyrazoles

“…Aromatic hydrazides are converted into indazol-3-ones when treated with an excess of butyllithium (Scheme 8.81) [245]. Benzoylhydrazines 275 afford 2H-indazol-3-ones 276 in 61-80% yield.…”

“…The same transformation has been carried out replacing butyllithium by sodium or potassium hydride, but the corresponding 2H-indazol-3-one was obtained in lower yields (49 and 56%, respectively, when R¼H). 2H-Indazol-3-ones 277-279 are obtained by the same procedure from appropriate aromatic hydrazides, while aliphatic and heterocyclic hydrazides afford the corresponding aldehydes [245].…”

Chemistry and heterocyclization of carbohydrazides

“…When phenyl carbohydrazide 1a in tetrahydrofuran (THF) was treated with n‐butyl‐lithium 84 in hexane under nitrogen atmosphere at −78°C for 1.5 h and allowed to reach the room temperature overnight, indazol‐3(2 H )‐one 88 was isolated [64]. …”

“…Condensation of indole carbohydrazide 1 with aromatic aldehydes gave the corresponding hydrazone derivatives 179 were obtained in varying yields, which heated to reflux in acetyl chloride to give the interesting tricyclic indolo[2,3‐ d ]pyridazine derivatives 180 rather than indenotriazines 181 [64]. …”

“…Acetylation of 1 by refluxing in acetic acid afforded 2‐acetyl‐hydrazinocarbonylindole 182 , in high yield. Compound 182 was cyclized directly by refluxing in dioxane containing POCl 3 to the indolo[3,2‐ b ]pyradizines 183 [64]. On the other hand, refluxing 1 in formic acid for 5 h afforded the N ‐formyl derivative 184 , which was heated for 10 min in ethanol to afford 2,3‐dihydro‐indolo[3,2‐ b ]pyridazin‐1‐one 185 [64].…”