SPATIALLY FIXED OLIGOAMINES .4. FLEXIBILITY AND PROTONATION OF MEANDER-TYPE OCTAMINES

Meander-type octamines 6a and 6b possessing three piperazine units, tw o bicyclo[3.1.0]hexyl- and two azabicyclo[3.1.0]hexyl systems as build ing blocks, could be obtained by reductive amination of di(oxobicycloh exyl) piperazine 2 with piperazinyl-3-azabicyclohexane derivatives 5a/ b, respectively. The latter were synthesized from N-benzylchloroenamin e 11 and sodium borohydride and subsequent removal of the benzylic pro tection group. Conformation and molecular flexibility of the new oligo amines 6a and 6b were studied. Di- and tetraammonium species with defi nite location of the protons were generated from octamine 6b, X-Ray st ructural analysis of diammonium salt 14 .. 2 TFA was used to give an i nsight into the molecular arrangement of an (azoniabicyclohexyl)pipera zine trifluoromethane sulfonate unit.