Synthesis of 3,3′-Disubstituted Indolenines Utilizing the Lewis Acid Catalyzed Alkylation of 2,3-Disubstituted Indoles with TrichloroacetimidatesAcknowledgement is made to the Donors of the American Chemical Society Petroleum Research Fund for a New Directions award in support of this research (54823-ND1). The National Institute of General Medical Sciences (R15-GM116054) also provided financial support. NMR spectra were obtained at Syracuse University using instrumentation acquired with the assistance of the National Science Foundation (CHE-1229345). L. R. thanks the Laboratoire d’Excellence Multiscale Integrative Chemistry (LabEx MiChem) for a travel grant to facilitate study in the USA.
Received: 09 May 2017
Accepted after revision: 13 June 2017
11 July 2017 (eFirst)
Trichloroacetimidates function as effective electrophiles for the selective C3-alkylation of 2,3-disubstituted indoles to provide 3,3′-disubstituted indolenines. These indolenines are common synthetic intermediates that are often utilized in the synthesis of complex molecules. Effective reaction conditions utilizing Lewis acid catalysts have been determined, and the scope of the reaction with respect to indole and imidate reaction partner has been investigated. This chemistry provides an alternative to base promoted and transition-metal-catalyzed methods that are more commonly utilized to access similar indolenines.