Reaction of Indazole with Terminal Di-bromoalkanes and Their Subsequent Thermal Cyclization: A Facile Entry into Fused Indazole Ring Systems.

Abstract 1‐(ω‐Bromoalkyl)indazoles undergo a facile thermal intramolecular cyclization reaction in the neat form. The reactions do not require the use of a solvent or base and proceed in quantitative yields. Moreover, their corresponding 2‐substituted isomers also cyclize affording the same cycloadducts. These reactions provide a facile entry into the synthesis of fused indazole ring systems with potential medicinal properties.