Cadogan-Sundberg indole synthesis

What is Cadogan-Sundberg indole synthesis?

The Cadogan-Sundberg indole synthesis is a reaction that can be attributed to the pioneering work of Cadogan, who developed a method for producing carbazole via the reductive cyclization of aromatic nitro compounds with triethyl phosphite P(OEt)3 (see list of acronyms). Sundberg later expanded upon this technique by using it to generate indoles through the treatment of o-nitrostyrene with triethyl phosphite, as well as indolines from o-alkyl nitrobenzenes.

Cadogan-Sundberg indole synthesis - general reaction scheme
Cadogan-Sundberg indole synthesis

Hence, the process of forming indole through the reduction of o-nitrostyrenes is commonly known as the Cadogan-Sundberg indole synthesis.

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