Formation of 1,4‐Diketones by Aerobic Oxidative CC Coupling of Styrene with 1,3‐Dicarbonyl Compounds

Abstract

Convenient and direct: 1,4‐Dicarbonyl compounds are readily obtained through a one‐pot cerium‐catalyzed oxidative CC coupling in the presence of oxygen and subsequent fragmentation. The products are suitable precursors for heterocycles.

The enol form of (+)-(1R,4R)-3-benzoylcamphor

“…The structure determination of the title compound, (I), was performed as part of a project on the preparation of well defined chiral cerium(III) -diketonates (Niemeyer et al, 2005) which might be used in enantioselective oxidation reactions for the synthesis of the biologically important -hydroxy--dicarbonyl group (Christoffers & Werner, 2002;Christoffers et al, 2003Christoffers et al, , 2004Rö ssle et al, 2004).…”

Formation of δ‐Lactones with anti‐Baeyer–Villiger Regiochemistry: Investigations into the Mechanism of the Cerium‐Catalyzed Aerobic Coupling of β‐Oxoesters with Enol Acetates

“…The origin of this regioselectivity wasu nderstood to be as tereoelectronic effect within the so called Criegee intermediate of the BVO (see Scheme5below). [10] Lately, we were able to improvet hese reactions by using enol esters 2 insteado fo lefins. [1] Very recently,w eh ave discoveredanew aerobic, cerium-catalyzed coupling reaction of enol acetatesa nd b-oxoesters leading to d-lactonesw ith an 1,4-dicarbonyl moiety in the side chain.…”

“…This recent discovery is based on our earlier work, where we found an ew route for the preparation of 1,4-diketones 5 by oxidative coupling of b-oxoesters like compound 1 with styrene. [10] Lately, we were able to improvet hese reactions by using enol esters 2 insteado fo lefins. [11] The cerium-catalyzedr eactionu tilizes molecular oxygen (from the air) and can be regarded as an oxidativeu mpolung reaction.…”

An optically active heteroleptic cerium camphorate: [bis(trimethylsilyl)amido-κN]bis[(+)-(1R,4R)-3-(trifluoroacetyl)camphorato-κ2O,O′](1,3,5-trimethyl-1,3,5-triazacyclohexane-κ3N,N′,N′′)cerium(III)

“…The Ce III -catalyzed -hydroxylation of -diketo compounds with molecular oxygen is a mild atom-economic and environmentally friendly method for the synthesis of the biologically important -hydroxy--dicarbonyl group (Christoffers & Werner, 2002;Christoffers et al, 2003Christoffers et al, , 2004Rö ssle et al, 2004). The structure determination of the title compound, (I), was performed as part of a project on the preparation of well defined chiral cerium(III) complexes which might be used for enantioselective oxidation reactions.…”