Intramolecular dearomative 1,4-addition of silyl and germyl radicals to a phenyl moiety

Herein, we present that the radicals [Ph3PC(Me)EMes2] (2Si and 2Ge) can be generated from the alpha-silylated and alpha-germylated phosphorus ylides Ph3PC(Me)E(Cl)Mes2 (1Si and 1Ge) through one-electron reduction with Jones' dimer (MesNacNacMg)2 in benzene. Although isolation of the free radicals was not possible, the products of the intramolecular addition of the radicals to a phenyl substituent of the phosphorus moiety, followed by subsequent reaction with 2Si or 2Ge to the isolated species 3Si and 3Ge, respectively, were observed. This transformation witnesses a dearomative 1,4-addition of tetryl radical species to the phenyl scaffold in a stereoselective anti-fashion. Ylide-functionalised radicals: Tetryl radicals 2Si and 2Ge can be generated by reduction of suitable ylide-functionalised precursors and undergo instant cyclization reaction with a phenyl moiety, which is rarely found in the case of germyl radicals.