The hydroauration of internal and terminal alkynes by gold(III) hydride complexes [(C^N^C)AuH] was found to be mediated by radicals and proceeds by an unexpected binuclear outer-sphere mechanism to cleanly form trans-insertion products. Radical precursors such as azobisisobutyronitrile lead to a drastic rate enhancement. DFT calculations support the proposed radical mechanism, with very low activation barriers, and rule out mononuclear mechanistic alternatives. These alkyne hydroaurations are highly regio- and stereospecific for the formation of Z-vinyl isomers, with Z/E ratios of >99:1 in most cases.
Stereo- and Regioselective Alkyne Hydrometallation with Gold(III) Hydrides / Pintus, A.; Rocchigiani, L.; Fernandez Cestau, J.; Budzelaar, Petrus Henricus Maria; Bochmann, M.. - In: ANGEWANDTE CHEMIE. INTERNATIONAL EDITION. - ISSN 1433-7851. - 55:40(2016), pp. 12321-12324. [10.1002/anie.201607522]
Stereo- and Regioselective Alkyne Hydrometallation with Gold(III) Hydrides
BUDZELAAR, Petrus Henricus Maria;
2016
Abstract
The hydroauration of internal and terminal alkynes by gold(III) hydride complexes [(C^N^C)AuH] was found to be mediated by radicals and proceeds by an unexpected binuclear outer-sphere mechanism to cleanly form trans-insertion products. Radical precursors such as azobisisobutyronitrile lead to a drastic rate enhancement. DFT calculations support the proposed radical mechanism, with very low activation barriers, and rule out mononuclear mechanistic alternatives. These alkyne hydroaurations are highly regio- and stereospecific for the formation of Z-vinyl isomers, with Z/E ratios of >99:1 in most cases.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
