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Indole ring is widely represented in natural compounds, as well as in a great variety of drugs. In this paper, the synthesis of a 5-hydroxybenzoindole derivative carrying a pyridyl substituent on position 1 is reported. The method involved no chromatography for purification and used solvents and catalysts of very low toxicity. [ABSTRACT FROM AUTHOR]

Indole ring is widely represented in natural compounds, as well as in a great variety of drugs. In this paper, the synthesis of a 5-hydroxybenzoindole derivative carrying a pyridyl substituent on position 1 is reported. The method involved no chromatography for purification and used solvents and catalysts of very low toxicity.

In this work, mild Lewis acids and low environmental impact solvents were investigated for Nenitzescu synthesis. Cyclopentyl methyl ether can be used at room temperature in substitution of halogenated solvents with zinc, iron and magnesium salts as homogeneous catalysts to give 5‐hydroxyindoles in fair to good yields. The reaction features a straightforward workup and excellent solvent recycle. [ABSTRACT FROM AUTHOR]

Versatile role of λ3‐iodanes has been identified between the reaction of hydroquinone and β‐enaminones for the synthesis of 5‐acyloxy‐4‐hydroxy indoles. The reaction is proposed to proceed through an intermolecular C−C bond formation, intramolecular cyclization, acyloxylation and 1,4‐acyl migration. The important features of this work include various acyloxylation from λ3‐iodanes and broad functional group tolerance to deliver 34 examples in moderate to good yields. [ABSTRACT FROM AUTHOR]

A modification of the Nenitzescu reaction was used to obtain Dronedarone from quinonimine 20 and 1,3-diketone 14 (R = CH 2 CH 2 CH 2 NBu 2 ) in a two-stage process in almost 55% overall yield. Our results represent significant improvement over other state-of-the-art methods as no extra steps for the decoration of the benzofuran core are required. [ABSTRACT FROM AUTHOR]

The manufacturing synthesis of 5-hydroxy-2-methyl-1 H-indole is described and two synthetic methods were used and the results discussed. Two small and three large runs with Nenitzescu's method were analyzed and results reported with different reaction conditions. Manufacturing issues encountered were discussed. Production scale of more than 60 kg of the 5-hydroxy-2-methyl-1 H-indole-3-carboxylic acid ethyl ester and over 20 kg of the 5-hydroxy-2-methyl-1 H-indole were achieved. Based on these results, larger scale manufacturing of this product or similar products based on the optimized conditions is feasible. [ABSTRACT FROM AUTHOR]

Abstract: Diethyl naphthoquinone-2,3-dicarboxylate reacts with different enamines to give 5-oxo-1,5-dihydro-benzo[g]indole-3,4,9b-tricarboxylate derivatives by migration of one ethoxycarbonyl group. These new products aromatize to planar indoles by elimination of one ethoxycarbonylgroup. With an N,N-dimethyl-enamine cyclization yields a 5-oxo-4,5-dihydro-cyclopenta[a]naphthalene-3,3a,4-tricarboxylate as well as a naphthyl-malonic acid derivative by migration of an ethoxycarbonylgroup. [Copyright &y& Elsevier]