Alkyne-aldehyde reductive C-C coupling through ruthenium-catalyzed transfer hydrogenation: direct regio- and stereoselective carbonyl vinylation to form trisubstituted allylic alcohols in the absence of premetallated reagents.

Autor: Leung JC; University of Texas at Austin, Department of Chemistry and Biochemistry, 1 University Station, A5300, Austin, TX 78712-1167, USA., Patman RL, Sam B, Krische MJ
Jazyk: angličtina
Zdroj: Chemistry (Weinheim an der Bergstrasse, Germany) [Chemistry] 2011 Oct 24; Vol. 17 (44), pp. 12437-43. Date of Electronic Publication: 2011 Sep 27.
DOI: 10.1002/chem.201101554
Abstrakt: Nonsymmetric 1,2-disubstituted alkynes engage in reductive coupling to a variety of aldehydes under the conditions of ruthenium-catalyzed transfer hydrogenation by employing formic acid as the terminal reductant and delivering the products of carbonyl vinylation with good to excellent levels of regioselectivity and with complete control of olefin stereochemistry. As revealed in an assessment of the ruthenium counterion, iodide plays an essential role in directing the regioselectivity of C-C bond formation. Isotopic labeling studies corroborate reversible catalytic propargyl C-H oxidative addition in advance of the C-C coupling, and demonstrate that the C-C coupling products do not experience reversible dehydrogenation by way of enone intermediates. This transfer hydrogenation protocol enables carbonyl vinylation in the absence of stoichiometric metallic reagents.
(Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
Databáze: MEDLINE
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