Cross‐Metathesis of Terminal Alkynes

E-ISSN： 1521-3765|20|41|13188-13193

ISSN： 0947-6539

Source： CHEMISTRY - A EUROPEAN JOURNAL, Vol.20, Iss.41, 2014-10, pp. : 13188-13193

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Abstract

AbstractTerminal acetylenes are amongst the most problematic substrates for alkyne metathesis because they tend to undergo rapid polymerization on contact with a metal alkylidyne. The molybdenum complex 3 endowed with triphenylsilanolate ligands, however, is capable of inducing surprisingly effective cross‐metathesis reactions of terminal alkyl acetylenes with propynyl(trimethyl)silane to give products of type R1CCSiMe . This unconventional way of introducing a silyl substituent onto an alkyne terminus complements the conventional tactics of deprotonation/silylation and excels as an orthogonal way of alkyne protecting group chemistry for substrates bearing base‐sensitive functionalities. Moreover, it is shown that even terminal aryl acetylenes can be cross‐metathesized with internal alkyne partners. These unprecedented transformations are compatible with various functional groups. The need to suppress acetylene formation, which seems to be a particularly effective catalyst poison, is also discussed.