From Alcohols to Indoles: A Tandem Ru Catalyzed Hydrogen-Transfer Fischer Indole Synthesis

Abstract

In a new version of the Fischer indole synthesis, primary and secondary alcohols have been catalytically oxidized in the presence of phenylhydrazines and protic or Lewis acids to give the corresponding indoles. The overall reaction can be accomplished in one step, and the use of alcohols instead of aldehyes or ketones as starting materials has several advantages in terms of a large selection of reagents, easy handling, and safety of the process.

Heterogeneous Palladium‐Catalyzed Hydrogen‐Transfer Cyclization of Nitroacetophenones with Benzylamines: Access to C−N Bonds

“…On the basis of the control experiments and previous reports, we propose a plausible reaction mechanism shown in Scheme . First, dehydrogenation of benzylamine ( 1 a ) produces imine 5 b as well as the palladium–hydride species PdH 2 , which reduces 2 a into 2 a′ in situ.…”

Benefits and applications of microwave-assisted synthesis of nitrogen containing heterocycles in medicinal chemistry

“…Antimicrobial activity can also be attained with new bis-pyrrole derivatives from hydrazonoyl halides. 28 The results revealed that most of the tested compounds exhibit better activity against Gram-positive bacteria over Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli), and one of them was found to be the most potent relative to the Atorvastatin, known commercially as Lipitor, is a drug used to treat high cholesterol, and is also a well-known pyrrole-containing derivative (Fig. 3).…”

Recent Advances in Cascade Reactions Initiated by Alcohol Oxidation

“…Pyrroles are another important synthetic target accessible through direct dehydrogenative coupling of unmasked β‐amino alcohols with alcohols or ketones with Ir‐PNP and Ru‐PNN pincer catalysts (Scheme ) . Related indoles are produced from primary and secondary alcohols in the presence of phenylhydrazines and protic or Lewis acids (Scheme ) . This approach allows the generation of sensitive carbonyl compounds in situ, which thus avoids the use of unstable enolizable aldehydes in the classical Fischer indole synthesis.…”