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DOI: 10.1055/s-2008-1078652
Preparation of a,b-Unsaturated Ketones from Alkynes and Aldehydes
Contributor(s):Yasuhiro Uozumi, Yoichi M. A. YamadaIndian Institute of Chemical Technology, Hyderabad, India
The Cation Exchange Resin-Promoted Coupling of Alkynes with Aldehydes: One-Pot Synthesis of α,β-Unsaturated Ketones
Tetrahedron Lett. 2008, 49: 4498-4500
Publication History
Publication Date:
22 August 2008 (online)
Key words
acid catalysis - alkynes - aldehydes - a,b-unsaturated ketones - cation-exchange resins
Significance
A cation exchange resin catalyzed coupling reaction of alkynes and aldehydes is reported. Thus, the reaction of monosubstituted alkynes 1 (R¹ = Alk, Ar) and aldehydes 2 (R² = H, Alk, Ar) was carried out with Amberlyst-15 to give the corresponding products 3 in 70-90% yield. The coupling of disubstituted alkynes 4 (R³ = Alk) with formaldehyde 5 was performed under similar conditions to afford a mixture of vinyl ketones 6 and 1,3-dioxane 7 in 78-85% yield with 2:1 selectivity.
Comment
The catalyst was reused three times with a slight loss of catalytic activity. The authors suggested that the reaction proceeds via cyclic oxete intermediates 8 from the results of a deuterium-labeling experiment. The reaction did not work in the presence of Montmorillonite KSF and a heteropoly acid H3PW12O40 in place of Amberlyst-15.