Free‐Radical Carbocyanation of Olefins

The free-radical 3-component carbo-cyanation of electron-rich olefins has been investigated using p-tosyl cyanide as a cyanide source. Scope and limitation of the process was established varying the nature of the alkene and that of the 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 through 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