Previous transition metal-catalyzed synthesis processes of δ-diketones are plagued by the high cost of the rhodium catalyst and harsh reaction conditions. Herein a low-cost, roomtemperature ruthenium catalytic method is developed based on the coupling of α-keto sulfoxoniumylides with cyclopropanols. The mild protocol features a broad substrate scope (47 examples) and a high product yield (up to 99%)
Cu(OAc)2, and dioxygen in molten tetrabutylammonium acetate (TBAA) promotes an unusual cyclopropanation reaction between arylmethylketones and styrenes. The process is a dehydrogenative cyclizing coupling that involves a twofold CH activation at the α‐position of the ketone. The substrate scope highlights the flexibility of the catalyst; a reaction mechanism is also proposed.
Enaminone Intermediate in the One-Methylene Incorporated Dimerization Reaction of Ketone Enolate. Cross Reaction to Unsymmetrical 1,5-Diketones
作者:Syun-ichi Kiyooka、Tsuneo Yamashita
DOI:10.1246/cl.1987.1775
日期:1987.9.5
An enaminone has been isolated as an intermediate from the one-methylene incorporated dimerization reaction of ketoneenolate using N-phenyl-N-methylformamide. The reaction of the enaminone with the other ketoneenolates gives unsymmetrical 1,5-diketones in good yields.
Generation of β-Keto Radicals from Cyclopropanols Catalyzed by AgNO<sub>3</sub>
作者:Shunsuke Chiba、Zhengyan Cao、Serry Atta Atta El Bialy、Koichi Narasaka
DOI:10.1246/cl.2006.18
日期:2006.1
Various β-keto radicals are generated from cyclopropanols by treatment with a catalytic amount of AgNO3 and (NH4)2S2O8 as a reoxidant in the presence of pyridine. Thus, generated β-keto radicals react with alkenes to yield addition products.
One-pot synthesis of Robinson annulated 3-aryl-cyclohexenones from allyl alcohols and ketones using palladium is reported. Long chain aliphatic or aryl substitutions at the C1 position of allyl alcohol result in the formation of 1,5-diketone products. This simple one-pot method avoids the use of highly electrophilic vinyl ketones.