Selective Magnesiation or Zincation of Highly Functionalized Alkenes and Cycloalkenes Using 2,2,6,6-Tetramethylpiperidyl Bases
作者:Tomke Bresser、Paul Knochel
DOI:10.1002/anie.201006641
日期:2011.2.18
Smooth and mild: Mg or Zn TMP bases (TMP=2,2,6,6‐tetramethylpiperidyl) allow the smooth metalation of various types of polyfunctional unsaturated substrates. Several sensitive functional groups such as ester, nitro, or trifluoromethylcarbonyl groups are tolerated. The new Zn or Mg intermediates undergo acylation, allylation, or cross‐coupling reactions in satisfactory yields.
desulfurization-condensation reaction was investigated in the presence of silver(I) salt for several kinds of thiocarbonyl compounds with nucleophiles. Such thiocarbonyl compounds as 4,4′-bis(dimethylamino)thiobenzophenone, ethylene trithiocarbonate, and N-(thiobenzoyl)morpholine react with malononitrile or other active methylene compounds in the presence of silver trifluoroacetate to afford the corresponding
Trimethylsilyl chloride assisted conjugate addition-elimination of organocopper reagents to 2-bis(methylthio)nitroethylene: An efficient and highly stereoselective synthesis of 2-methylthio-2-alkyl/aryl-1-nitroethylenes and their application for synthesis of nitroheterocycles
作者:Nobin Terang、Barun K Mehta、H Ila、H Junjappa
DOI:10.1016/s0040-4020(98)00790-x
日期:1998.10
An efficient method for the synthesis of novel 2-methylthio-2-alkyl/aryl-1-nitroethylenes 2 has been developed via conjugate addition-elimination of organocopper reagents to nitroketene dithioacetal 1 in the presence of TMSCl. The product nitroethylenes 2 have been further utilized for the synthesis of substituted 3-nitro-2-alkyl/arylpyrroles 5 by their reaction with aminoacetaldehyde dimethylacetal
The palladium-catalyzed cross-dehydrogenative-coupling (CDC) reaction of internal alkenes (α-nitro ketene dithioacetals) and terminal alkenes (acrylates) was achieved in AcOH/DMSO using air or AgOAc as the sole oxidant. Styrenes were also applied in the CDC reaction of these internal alkenes with AgOAc as the oxidant. Polyfunctionalized 1,3- and 1,4-dienes were obtained in moderate to excellent yields