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

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 regi...

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Bibliographic Details
Published in:Chemistry : a European journal 2011-10, Vol.17 (44), p.12437-12443
Main Authors: Leung, Joyce C., Patman, Ryan L., Sam, Brannon, Krische, Michael J.
Format: Article
Language:English
Subjects:
Aldehydes
Aldehydes - chemistry
Alkynes
Alkynes - chemistry
Carbonyls
Catalysis
Formic acid
green chemistry
homogeneous catalysis
Hydrogenation
Indicators and Reagents - chemistry
Joining
Molecular Structure
Olefins
Propanols - chemistry
ruthenium
Ruthenium - chemistry
Stereochemistry
Stereoisomerism
transfer hydrogenation
vinylation
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Summary: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. Fun with formate: Under the conditions of ruthenium‐catalyzed transfer hydrogenation employing formic acid as the terminal reductant, nonsymmetric 1,2‐disubstituted alkynes engage in reductive coupling to aldehydes, delivering the products of carbonyl vinylation with good to excellent levels of regioselectivity and with complete control of the olefin stereochemistry (see scheme).
ISSN:0947-6539
1521-3765
DOI:10.1002/chem.201101554