First efficient preparation of enantiopure 10-bromofenchone: the key intermediate to C10-substituted fenchone-derived chiral sources

The first efficient preparation of enantiopure 10-bromofenchone from commercially available fenchone is described. The synthetic procedure is based on two consecutive Wagner–Meerwein rearrangements of the fenchone skeleton, taking place straightforwardly in only three individual steps with a high overall yield. The ability of the bromine atom to be substituted by other functional groups makes 10-bromofenchone a key intermediate for the preparation of interesting C10-substituted fenchone-derived chiral sources, which are topologically different and analogous to well-known C10-substituted camphor-derived chiral tools.