CATALYTIC PREPARATION OF AZIRIDINES WITH AN IRON LEWIS-ACID

The iron Lewis acid, [(eta(5)-C5H5)Fe(CO)(2)(THF)](+)[BF4](-), was fou nd to be an effective catalyst for the preparation of aziridines. This new method provides a facile, one-step route to predominantly cis-azi ridines, with yields up to 95%, from compounds with a diazo functional ity and a variety of substituted N-benzylidene imines with N-aryl or N -alkyl groups. The reaction mechanism is believed to proceed through a n electrophilic iminium ion intermediate. To support this idea, the ir on Lewis acid-imine complex [(eta(5)-C5H5)Fe(CO)(2)(PhCH=NPh)](+)[BF4] (-) was prepared, characterized, and reacted with different diazo comp ounds to provide the resultant cis-aziridines. Alternatively, it may b e possible that the aziridines were derived from an electrophilic carb enoid intermediate, as is often proposed. Thus, the iron carbene [(eta (5)-C5H5)Fe(CO)(2)(CHPh)](+)[SO3CF3](-) was prepared and treated with N-benzylideneaniline; however, the resultant aziridine was not formed.