The free-radical three-component carbocyanation of electron-rich olefins was investigated with p-tosyl cyanide as cyanide source. The scope and limitations of the process were established by varying the nature of the alkene and radical precursor. Carbocyanation of chiral allylsilanes was shown to occur with high diastereocontrol, leading to syn β-silyl nitriles. The origin of the stereocontrol was rationalized by a Felkin-Anh-type transition-state model. Finally, a tin-free carbocyanation process was also devised, based on the use of a new alkylsulfonyl cyanide incorporating both carbon fragments to be added across the olefinic π system.
Cobalt supported on alumina (10 wt% Co/Al 2 O 3 ) was synthesized by three different methods; sol-gel (SG), microemulsion (ME) and impregnation (IMP). The materials were characterized by the Brunauer-Emmett-Teller (BET) method, X-ray diffraction (XRD), X-ray fluorescence, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. Their catalytic activity was investigated toward the formation of Biginelli reaction products, 3,4-dihydropyrimidin(1H)-ones (DHPMs). The catalysts were found to be efficient for this reaction with yields between 50% and 71% and can be reused without great loss of efficiency. Among the catalytic systems, that prepared by the SG method is the most active with 71% of DHPMs yield under solvent free conditions at 100°C for 1 h of reaction time.
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