Synthesis of a Novel Type of 2,3'-BIMs via Platinum-Catalysed Reaction of Indolylallenes with Indoles

Lisa Cooper, José Miguel Alonso, Louise Eagling, Helen Newson, Sachini Herath, Christopher Thomson, Andrew Lister, Catherine Howsham, Brian Cox, María Paz Muñoz

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Abstract

Optimisation, scope and mechanism of the platinum-catalysed addition of indoles to indolylallenes is reported here to give 2,3'-BIMs with a novel core structure very relevant for pharmaceutical industry. The reaction is modulated by the electronic properties of the substituents on both indoles, with the 2,3'-BIMs favoured when electron donating groups are present. Although simple at first, a complex mechanism has been uncovered that explains the different behaviour of these systems with platinum when compared with other metals (e.g. gold). Detailed labelling studies have shown Pt-catalysed 6-endo-trig cyclisation of the indollylallene as the first step of the reaction and the involvement of two cyclic vinyl-platinum intermediates in equilibrium through a platinum carbene, as the key intermediates of the catalytic cycle towards the second nucleophilic attack and formation of the BIMs.
Original languageEnglish
Pages (from-to)6105-6114
Number of pages10
JournalChemistry - A European Journal
Volume24
Issue number23
Early online date5 Mar 2018
DOIs
Publication statusPublished - 20 Apr 2018

Keywords

  • platinum
  • allene
  • indole
  • bisindolylmethane
  • mechanism

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