The first synthesis of an anti-Bredt bicyclic hydantoin containing an imide bridghead nitrogen was accomplished. In this procedure 3-bromo-e-caprolactam (14) was converted to 3-cyano-ecaprolactam (15). A key reaction was the phenylation of 15 using Ph5Bi to provide 3-cyano-3-phenyl-e-caprolactam (18), although limitations of this procedure were revealed by unsuccessful efforts with closely related structures. Nitrile 18 was hydrolyzed to the 3-carboxamide 20, which underwent a Hofmann rearrangement in the presence of Pb(OAc)4and 2,6-lutidine. The rearrangement of 20 was accompanied by intramolecular attack of the lactam nitrogen on the intermediate isocyanate to give the final product, l,7-diaza-8,9-dioxo-6-phenylbicyclo[4.2.1]nonane (5). Thus 5 was formed from 14 in five steps and an overall yield of 17%. The structural assignment of 5 was supported by an 15N NMR study. © 1990, American Chemical Society. All rights reserved.