Tin dichloride reduction

This reaction was also studied with a more complicated nitro ketoester starting material [10]. hi this example, the nucleophilic addition occurs intramolecularly to form a 15-membered macrocycle. Zinc/ammonium chloride reduction to form the hydroxyindole 16 followed by cyclization provided a better yield of 17 (40% over both steps) than the direct tin dichloride reduction of 15 to macrocycle 17 (10%). 

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