Industrial & Engineering Chemistry Research, Vol.42, No.23, 5721-5726, 2003
Preparation of alkyl 4,5-dihydro-2H-benz[g]indazole-2-carboxylates and methyl 4,5-dihydro-2H-benz[e]indazole-2-carboxylates from dilithiated 1-tetralone or 2-tetralone carboalkoxyhydrazones and aromatic esters
Dilithiated 1-tetralone or 2-tetralone carboalkoxyhydrazones were prepared in excess lithium diisopropylamide and condensed with a variety of aromatic esters followed by acid cyclization of C-acylated intermediates to give substituted dihydrobenzindazoles, alkyl 4,5-dihydro-2H-benz-[g]indazole-2-carboxylates and methyl 4,5-dihydro-2H-benz[e]indazole-2-carboxylates. These fused-ring heterocyclic products have considerable application potential.