Schmidt reaction of 4-substituted adamantanones

The Schmidt reaction of various 4^a - and 4^e -substituted adamantanones has been investigated. It is shown that the direction of the nitrogen insertion is not dominated by inductive substituent influences. The main reaction pathway involves the diazoiminium ion 3 and the intermediates 4 and 5 which prefer different reactions: 4 undergoes mainly fragmentation (8 and 9) whereas 5 gives mainly water addition products (7). The recyclisation of 8 and 9 is highly regloselective. The structure determinations of the products are based on their ¹H and ¹³C NMR data.