Controlled Activation of Dipicolinyl-Substituted Propargylic Alcohol by Ru(II) and Os(II) for Unprecedented Indolizine-Fused Metallafuran Complexes

Indolizine-fused metallafuran and
metal–quinolizinium complexes
were synthesized from reactions between dipicolinyl-substituted propargylic
alcohol HCCC­(OH)­(CH2(2-py))2 and cis-[Ru/Os­(dppm)2Cl2] (dppm = 1,1-bis­(diphenylphosphino)­methane),
revealing the operation of both non-vinylidene and vinylidene pathways
regarding the Ru­(II)/Os­(II)–alkyne interactions. Strategies
to control the selectivity of these two competitive pathways were
successfully developed, paving ways to the rational design of Ru/Os-induced
alkyne activations and metallacycles.