A Palladium-Catalyzed Method for the Preparation of Indoles via the Fischer Indole Synthesis
Citations Over TimeTop 1% of 1999 papers
Abstract
A Pd-catalyzed method for the preparation of N-aryl benzophenone hydrazones 4 is described. The use of a Pd/BINAP-based catalyst provides hydrazones 4 in good yields. Using 0.1 mol % of a Pd/9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene (Xantphos) catalyst, the desired hydrazones are produced in excellent yields. The N-aryl benzophenone hydrazones are converted to indole products via an in situ hydrolysis/Fischer cyclization protocol. A procedure that extends this methodology to the synthesis of N-alkylindoles via the intermediacy of N-aryl-N-alkyl benzophenone hydrazones is described. Additionally, the Pd-catalyzed preparation of diaryl benzophenone hydrazones, followed by a hydrolysis/Fischer cyclization protocol, affords N-arylindole products in good yields. This methodology provides a means for the preparation of a structurally diverse set of indoles from simple, (usually) commercially available precursors.
Related Papers
- → Preparation of diphenylmethyl esters by oxone® oxidation of benzophenone hydrazone(1997)35 cited
- Facile synthesis of water-soluble polymeric benzophenone photoinitiators(2013)
- Improvement on synthesis technology of phamaceutical intermediate benzophenone hydrazone(2011)
- Synthesis of 4-Bromomethyl Benzophenone.(2003)
- Improved synthesis of benzophenone hydrazone(2003)