On the mechanism of the Fe(CO)5-catalyzed Kharasch reaction

Regioselectivity and diastereoselectivity of the addition of BrCCl₃ to (R)-3-(E)-cinnamoyl-4-phenyloxazolidin-2-one (1) and (R)-3-(E)-acryloyl-4-phenyloxazolidin-2-one (2) catalyzed by Fe(CO)₅ or initiated with benzoyl peroxide were investigated. Stereochemistry of the reaction of BrCCl₃ with the a-complexes (4R,S,S)-²-(3-(E)-cinnamoyl-4-phenyl-oxazolidin-2-one)irontetracarbonyl (3a) and (4R,R)-²-(3-acryloyl-4-phenyloxazolidin-2-one)irontetracarbonyl (4b) was also studied. The results obtained allow the following conclusions to be drawn: (1) the thermal Kharasch reaction catalyzed by Fe(CO)₅ proceeds by a redox catalysis mechanism; (2) iron (in any of its oxidation states) is not coordinated to olefins in the transition state of the reaction; (3) the transfer of the halogen atom on the radical adduct probably occurs inside a radical-iron cation pair.Yu. T. Struchkov is deceasedTranslated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 640–648, March, 1996.