Mannich bases exchange reactions in the synthesis of condensed dihydro-1, 5-benzodiazepines

Abstract EN

The reactions of the bis-Mannich bases (4a-d), the bis Mannich jbases.

(19a-d) and the mono-Mannich base (18) with o-phenylenediamine afford the condensed dihydro-1, 5 benzodiazepines (Wa-d), (21a-d) and (20) respectively.

The expected quinoxalines are not formed.

The reaction of the bis-Mannich bases (23a and 23b) - obtained from cyclohexane-1, 2-dione - with o-phenylenediamine neither gave quinoxalines nor dihydro-1, 5-benzodiazepines instead the tricyclic compound (6) was obtained.

The Mannich reactions of these cyclopentanes and cyclohexanes followed second order kinetics.