β-Carbonyl radicals as three-carbon building blocks for carbon-carbon bond forming reactions
作者:Bernd Giese、Hans Horler
DOI:10.1016/s0040-4020(01)97181-9
日期:1985.1
aldehydes, ketones and esters β-carbonyl radicals can be generated via enolization, cyclopropanation, solvomercuration and reduction with NaBH4. Radicals react with electron-poor alkenes to give products of CC-bond formingreactions (Tables 1–3). Carbonyl compounds are therefore precursors of three-carbon building blocks. The products result from reactions with “Umpolung”.
Tertiary cyclopropanol systems react with a catalytic amount of vanadyl acetylacetonate under an oxygen atmosphere to afford β-hydroxyketones and β-diketones.
.beta.-Trichlorostannyl ketones and aldehydes. Preparation and facile amine-induced dehydrostannation leading to .alpha.-methylene ketones and aldehydes
Ring-opening reactions of siloxycyclopropanes 1 with SnCl4 take place under mild reaction conditions and site-selectively to give beta-trichlorostannyl ketones and aldehydes 3 in high yields. The beta-trichlorostannyl ketones and aldehydes thus obtained readily undergo base-induced dehydrotrichlorostannation at room temperature to give the corresponding alpha-methylene ketones and aldehydes 4. The reactions are quite general for amines, such as pyridine, triethylamine, N,N,N',N'-tetramethylethylenediamine (TMEDA), and 1,4-diazabicyclo[2.2.2]octane (DABCO), and the yields are good to high. One-pot conversion from siloxycyclopropanes 1 to alpha-methylene ketones or aldehydes 4 by consecutive treatment of 1 with SnCl4 and TMEDA is also successful. The H-1 NMR, C-13 NMR, Sn-119 NMR, and IR spectral properties of beta-stannyl ketones and aldehydes are also reported.
Fragmentation of tertiary cyclopropanol compounds catalyzed by vanadyl acetylacetonate
Tertiary cyclopropanol compounds react with a catalytic amount of vanadyl acetylacetonate in the presence of oxygen affording beta-hydroxyketones and beta-diketones. For 3-substituted-bicyclo[4. 1.0]alkanols, peroxides are obtained, as are the beta-hydroxyketones. Conversely, 2-ethoxycarbonylcyclopropyl silyl ethers produce ethyl gamma-oxocarboxylate derivatives given the same reaction conditions. (c) 2005 Elsevier Ltd. All rights reserved.
Ryu, Ilhyong; Matsumoto, Koichi; Kameyama, Yasuhiro, Journal of the American Chemical Society, 1993, vol. 115, # 26, p. 12330 - 12339