1534-28-7Relevant academic research and scientific papers
One-carbon homologation of unsymmetrical ketones through magnesium β-oxido carbenoid rearrangement and trapping the enolate intermediates with electrophiles
Tanaka, Shu,Anai, Takehiro,Tadokoro, Makoto,Satoh, Tsuyoshi
, p. 7199 - 7210 (2008/12/20)
A procedure for one-carbon homologation of unsymmetrical ketones, including one-carbon ring-expansion of 2-substituted cyclohexanones, through magnesium β-oxido carbenoid rearrangement as the key reaction is described. Addition of the α-sulfinyl carbanion of 1-chloroethyl p-tolyl sulfoxide to an unsymmetrical ketone gave two diastereomers as adducts in good yields. The adducts were treated with a base to give alkoxides, which were treated with a Grignard reagent to give magnesium β-oxido carbenoids. The β-oxido carbenoid rearrangement then took place to afford one-carbon homologated ketones having a methyl group at the α-position. Remarkable specificity or selectivity was observed in the rearrangement. The magnesium enolate intermediates of this reaction were found to be able to get trapped with several electrophiles to give one-carbon homologated α,α-disubstituted ketones. Origin of the specificity and selectivity is also discussed.
Selectivity of Radical Formation in the Reaction of Carbonyl Compounds with Manganese(III) Acetate
Midgley, Gary,Thomas, C. Barry
, p. 1103 - 1108 (2007/10/02)
The selectivity of radical generation in the oxidation of carbonyl compounds by manganese(III) has been studied in two ways.Competitive reaction of acetic and propionic acids under conditions in which the resultant radicals are trapped efficiently by an alkene suggests that propionic acid reacts some 3.8 times more readily than does acetic acid.Oxidation of butanone under similar conditions gives products in the formation of which reaction has occurred 2.9 times more readily at C-3 of butanone than at C-1.However, this ratio reflects a combination of chain propagation and of initiation by manganese(III) oxidation.When propagation is effectively eliminated, the C-1 position is the more reactive.The significance of these observations on the mechanism of oxidation of carbonyl compounds by manganese(III) is discussed.It is suggested that enol radical-cations can be formed in the reaction but that these do not give carbonyl-stabilised radicals by deprotonation.
HIGHLY DISPERSED POTASSIUM ON ALUMINA AS A METALATING AGENT. ALKYLATION OF ENOLIZABLE COMPOUNDS
Savoia, Diego,Tagliavini, Emilio,Trombini, Claudio,Umani-Ronchi, Achille
, p. 281 - 286 (2007/10/02)
Highly dispersed potassium on alumina (K/Al2O3) acts as a metalating agent towards enolizable compounds and the intermediate organopotassium derivatives can be alkylated with primary alkyl bromides.The reaction conditions are dependent on the substrate.In particular, tetrahydrofuran is the solvent of choice for the metalation of nitriles and aldehyde N,N-dimethylhydrazones at -60 deg C and of N-cyclohexyl ketimines at room temperature, whereas hexane must be used for ketones.
