Hydrazides, lithiation

Acyl hydrazides are useful precursors for the synthesis of 1,2,4-triazoles. Reaction of acyl hydrazides 149 with imidoylbenzotriazoles 148 in the presence of catalytic amounts of acetic acid under microwave irradiation afforded 3,4,5-trisubstituted triazoles 150 <06JOC9051>. Treatment of A-substituted acetamides with oxalyl chloride generated imidoyl chlorides, which reacted readily with aryl hydrazides to give 3-aryl-5-methyl-4-substituted[ 1,2,4]triazoles <06SC2217>. 5-Methyl triazoles could be further functionalized through a-lithiation and subsequent reaction with electrophiles. ( )-A -(Ethoxymethylene)hydrazinecarboxylic acid methyl ester 152 was applied to the one-pot synthesis of 4-substituted-2,4-dihydro-3//-1,2,4-triazolin-3-ones 153 from readily available primary alkyl and aryl amines 151 <06TL6743>. An efficient synthesis of substituted 1,2,4-triazoles involved condensation of benzoylhydrazides with thioamides under microwave irradiation <06JCR293>. 

A small number of mixed anion complexes containing lithiated hydrazides have also been identified. 

Lithiation of aromatic compounds. Hydrazides of the constitution ArCONHNMe2 are lithiated at the ortho position. ... 

The —CONHNR2 group of aromatic and heterocyclic 2,2-dialkyl hydrazides is a powerful director of ortho and lateral lithiation. Lithiation at C(7) of l-(2,2-diethylbutenoyl)indoles is directed kinetically by a complex-induced proximity effect of the nitrogen substituent which can be removed readily. ... 

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