Synthesis of Carbonyl Compounds by Alkylation or Condensation
A highly efficient α alkylation of ketones with primary alcohols by the use of a recyclable palladium catalyst has been demonstrated.
M. S. Kwon, N. Kim, S. H. Seo, I. S. Park, R. K. Cheedrala, J. Park, Angew. Chem., 2005, 117, 7073-7075.
An unprecedented Rh-catalyzed direct methylation of ketones with N,N-dimethylformamide shows a broad substrate scope. Mechanistic studies suggest that DMF delivers a methylene fragment followed by a hydride during the methylation process.
Y. Li, D. Xue, W. Lu, C. Wang, Z.-T. Liu, J. Xiao, Org. Lett., 2014, 16, 66-69.
The Cu(acac)2-catalyzed cross-coupling of alkylzinc halides with α-chloroketones introduces primary and secondary alkyl groups adjacent to a ketone carbonyl under mild reaction conditions and in good yield. The reaction proceeds stereospecifically with inversion of stereochemistry.
C. F. Malosh, J. M. Ready, J. Am. Chem. Soc., 2004, 126, 10240-20241.
Indium(III) halide catalyzed the coupling of alkyl chlorides with silyl enolates derived from esters, ketones, and aldehydes to give various α-alkylated carbonyl compounds. A one-pot, three-component reactions of aldehyde enolates, alkyl chlorides, and allylsilanes or alkynylsilanes is described.
Y. Nishimoto, M. Yasuda, A. Baba, Org. Lett., 2007, 9, 4931-4934.
Photoirradiation of a mixture of acetone and water containing olefins affords the corresponding methyl ketones efficiently via a water-assisted C-C coupling between the acetonyl radical and olefins.
Y. Shiraishi, D. Tsukamoto, T. Hirai, Org. Lett., 2008, 10, 3117-3120.
An efficient and highly enantioselective conjugate addition of alkylzinc reagents to various cyclic nitroalkenes is promoted in the presence of 0.5-5 mol % (CuOTf)2·C6H6 and 1-10 mol % of chiral amino acid-based phosphine ligands at 0°C in toluene. Depending on the reaction conditions used, either the nitro or the corresponding α-substituted ketone product can be accessed.
C. A. Luchaco-Cullis, A. H. Hoveyda, J. Am. Chem. Soc., 2002, 124, 8192-8193.
Multifunctional palladium catalysis allows a one-pot stereocontrolled synthesis of tetrasubstituted methyl ketones and enynes. The homogeneous palladium dihalide catalyst is used for the bromo-/chloroallylation of alkynes and in situ for subsequent Wacker-Tsuji oxidation or Sonogashira cross-coupling.
A. N. Thadani, V. H. Rawal, Org. Lett., 2002, 4, 4321-4323.