Captodative substituent effects. XXI: Synthesis of selenenylated captodative olefins via selenenyl halide addition to olefins bearing electron-withdrawing substituents

摘要: Abstract Addition of methane- and benzeneselenenyl bromide or chloride benzene sulfenyl to carbon-carbon double bonds substituted by electronwithdrawing groups is achieved in solvents different polarity. Two regioisomeric adducts 6 7 8 9 are generally formed, which can be interconverted equilibration refluxing acetonitrile. It mechanistic interest that the regioisomers may also derive from selenenyltrihalide adducts. In comparison acrylic esters, propiolic ester reacts more slowly, producing mainly α-selenenyl adduct. Dehydrohalogenation provides a general valuable method for preparation olefins carrying methyl phenylselenenyl α-position electron-withdrawing substituents.