Synthesis of <i>N</i>,<i>N</i>′-Unsymmetrical 9-Amino-5,7-dimethyl-bispidines

A new approach to the preparation of N,N′-unsymmetrically substituted 9-aminobispidines through aminal bridge removal reaction has been developed, the principal feature of which is the ability to selectively functionalize all three nitrogen atoms. The intermediates of 1,3-diazaadamantane’s aminal bridge removal reaction are characterized, and the mechanism of this reaction is proposed based on the analysis of their structures. Representatives of the previously unknown saturated heterocyclic 1,5,9-triazatricyclo[5.3.1.03,8]undecane system were obtained and structurally characterized. Thus, it was possible for the first time to obtain 3,7,9-trisubstituted bispidines containing acetyl, Boc, and benzyl groups at nitrogen atoms, which can be independently removed (orthogonal protective groups).