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A practical method for the N-detosylation of indoles and related heterocycles with KOH in THF and water in the presence of a phase transfer catalyst is described. Using a nonalcoholic solvent, this method prevents the formation of toxic alkyl p-toluenesulfonate and consequently eliminates the formation of even traces of N-alkyl byproduct. This green method is particularly useful for indoles bearing electron-withdrawing groups and for azaindoles.

A concise large-scale synthesis of 1, a new antimitotic agent is described. The key step was a one-pot Sonogashira crosscoupling of an aryl halide with a heteroaryl halide through an acetylene using the readily available 2-methyl-3-butyn-2-ol ( 7). An innovative approach for palladium removal was designed and successfully scaled-up on a multikilogram scale. The product was crystallized from the crude reaction mixture while keeping the residual palladium in the mother liquor by using Pd-scavenging agents such as N-acetylcysteine or thiourea.

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