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Synthesis of a Novel Type of 2,3′‐BIMs via Platinum‐Catalysed Reaction of Indolylallenes with Indoles
Author(s) -
Cooper Lisa,
Alonso José Miguel,
Eagling Louise,
Newson Helen,
Herath Sachini,
Thomson Christopher,
Lister Andrew,
Howsham Catherine,
Cox Brian,
Muñoz María Paz
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201705417
Subject(s) - platinum , chemistry , nucleophile , combinatorial chemistry , catalysis , carbene , stereochemistry , organic chemistry
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.