Thiazolium-catalyzed intermolecular Stetter reaction of linear and cyclic alkyl α-diketones
An efficient method for the N-heterocyclic carbene (NHC)-catalyzed conjugate addition of acetyl anions to various α,β-unsaturated acceptors (Stetter reaction) has been optimized by using 2,3-butandione (biacetyl) as an alternative surrogate of acetaldehyde. The disclosed procedure proved to be compatible with microwave dielectric heating for reaction time reduction and with the use of different linear α-diketones as acyl anion donors (e.g. 3,4-hexanedione for propionyl anion additions). Moreover, the unprecedented umpolung reactivity of cyclic α-diketones in the atom economic nucleophilic acylation of chalcones is herein presented. Mechanistic aspects of the thiazolium-based catalysis involving linear and cyclic α-diketone substrates are also discussed. The Royal Society of Chemistry 2011.
Pd-catalyzed carbonylative conjugate addition of dialkylzinc reagents to unsaturated carbonyls
The Pd-catalyzed addition of organozinc reagents to unsaturated carbonyls in the presence of carbon monoxide provides 1,4-diketones in good yield. The reaction was studied with a number of substituted cyclic and acyclic ketones as well as α,β-unsaturated aldehydes.
Custar, Daniel W.,Le, Hai,Morken, James P.
supporting information; experimental part
p. 3760 - 3763
(2010/11/04)
PYRROLE DERIVATIVES AS THERAPEUTIC COMPOUNDS
Novel pyrrole derivatives are disclosed as Aβ42-lowering agents for the treatment and prevention of neurodegenerative disorders characterized by the formation or accumulation of amyloid plaques comprising the Aβ42 peptide.
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Page/Page column 39
(2010/11/26)
The Synthesis of 1,4-Diketones via Fluoride-catalysed Michael Addition and Supported-permanganate-promoted Nef Transformation
A versatile synthetic route for the preparation of 1,4-diketones from simple starting materials is described and applied to the preparation of a wide range of diketones.The two most important steps in the reaction are the fluoride ion-catalysed Michael addition of a nitroalkane to a vinyl ketone and the subsequent transformation of the nitro ketone to the diketone using supported permanganate as the oxidant.The interaction of F- with nitroethane has been studied and a number of sources of F- have been tested in the Michael addition reaction.Potassium fluoride supported on alumina and potassium permanganate supported on silica gel are remarkably efficient reagents for the Michael addition and Nef transformation stages, respectively, although it is important to determine the best reagent loadings and drying conditions for maximum reaction efficiency to be achieved.
Clark, James H.,Cork, David G.,Gibbs, Hugh W.
p. 2253 - 2258
(2007/10/02)
Synthesis of 1,4-Diketones by Fluoride-catalysed Michael Addition and Supported Permanganate Oxidation
A wide variety of 1,4-diketones may be prepared from simple starting materials by using fluoride ion-catalysed Michael additions and silica gel-supported permanganate-promoted Nef transformations.
Clark, James H.,Cork, David G.
p. 635 - 636
(2007/10/02)
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