268750-56-7Relevant academic research and scientific papers
Intercalation of multiple carbon atoms between the carbonyls of α-diketones
Balskus,Mendez-Andino,Arbit,Paquette
, p. 6695 - 6704 (2007/10/03)
The reaction of open-chain or cyclic α-diketones with specific ω-alkenyl organometallics leads readily under the proper conditions to 1,2-diols bonded to terminal olefinic chains. With 1-phenyl-1,2-propanedione, biacetyl, and cyclohexane-1,2-dione, allylindation in aqueous THF proceeds readily at both adjacent carbonyls. For cyclododecane-1,2-dione, recourse must be made to allylmagnesium bromide for completing the second-stage condensation. Grignard reagents have also served well as reactants for biacetyl monoadducts. In contrast, monoallylated camphorquinone is reluctant to couple to Grignard reagents and reacts only when Barbier-type alkyllithium reactions are applied. The ring closing metatheses of these products have been examined. Where six-membered ring formation operates, cyclization can be performed directly on diols. When larger rings are involved, the diols will react only if structural preorganization capable of facilitating mutual approach of the two double bonds is at play. For this purpose, the prior conversion to a cyclic carbonate holds considerable utility. In the latter setting, saponification must precede the diol cleavage step which has been performed with lead tetraacetate. The latter reagent also exhibits the very beneficial effect of facilitating removal of ruthenium and phosphorus byproducts generated during the metathesis step. This chemistry conveniently lends itself to the controlled intercalation of multiple methylene groups between the carbonyl carbons of readily available α-diketones to deliver linear or cyclic products.
Tandem deployment of indium-, ruthenium-, and lead-promoted reactions. Four-carbon intercalation between the carbonyl groups of open-chain and cyclic α-diketones
Mendez-Andino, Jose,Paquette, Leo A.
, p. 1263 - 1265 (2007/10/03)
(equation presented) An efficient strategy for the conversion of 1,2-diketones into saturated 1,6-diketones and Δ2,3/Δ3,4-unsaturated congeners thereof is reported.
A Convergent Synthesis of Symmetrical Carotenoids Using the Heck Reaction
Bienayme, Hugues
, p. 6867 - 6868 (2007/10/02)
Regioselective Heck-type vinylation of various allylic alcohols with 2, followed by an acidic dehydration, delivers symmetrical carotenoids in good yields. - Key words: Heck vinylation; Palladium; Carotenoids; β-Carotene
Regio- and stereochemistry in the sequential insertion of carbonyl compounds into zirconium-diene complexes
Yasuda, Hajime,Okamoto, Takuji,Mashima, Kazushi,Nakamura, Akira
, p. 61 - 76 (2007/10/02)
Group 4 metal-diene complexes of the type Zr(η-C5H5)2(s-cis-diene) and Zr(η-C5H5)2(s-trans-diene) (diene=butadiene, isoprene, pentadiene and their derivatives) were found to undergo regioselective 1/1 addition with a variety of aldehydes, ketones, esters and acid amides at the sterically more crowded terminal carbon of the ligated diene to give the (Z)-oxazirconacyclo-4-heptenes.Further addition of carbonyl compounds to the resulting oxametallacycle leads to 1/2 adducts of (E)-1,3-dioxazircona-6-nonene structure when the precursor oxazirconacycloheptene has a less bulky hydrogen group at the C(5) position.Highly selective, three-component, sequential addition was first realized by treatment of a ketone or an aldehyde with Zr(C5H5)2(diene)/ester, Zr(C5H5)2(diene)/alkene and Zr(C5H5)2(diene)/alkyne adducts.
