Synthesis And Characterization Of New Organic Non-ionic Superbases

Organic non-ionic superbases have received great attention due to their good solubility in organic solvents and high catalytic efficiency in modern organic transformations. Proazaphosphatranes, also known as Verkade Base (a kind of strong nonionic phosphorus-bases), features a structure of bicyclic rings with N-P atom as the bridge. Phosphorus atom is the center to provide electrons for the basicity. Organic reactions mediated by proazaphosphatranes are homogeneous and generally goes smoothly without significant side reactions, which is often problematic for an ionic bases-mediated reaction.This thesis includes the following parts: Chapter1, Introduction; Chapter 2, Synthesis of tetramines; Chapter 3, Synthesis of N-substituted tetramines; Chapter 4, Synthesis of novel non-ionic superbases. The target products and intermediate products were characterized by elemental analysis,IR,1H NMR,13C NMR and 31P NMR, etc.Various protocols were devoleped in this thesis for the synthesis of tetramines, their derivatives and superbases. Such as:1) Under reflux condition, the primary end amino groups were first protected by acetyl groups, through the reaction of amine with ethyl acetate(molar ratio was 1:4). The secondary amino group reacted with acrylonitrile to form the nitrile intermediate. The nitrile group of the intermediate was reduced by hydrazine in the presence of Raney Ni,then the acetyl groups were hydrolyzed, the first tripodal tetramine bis(2-aminoethyl)-(3-aminopropyl) amine was obtained.2) The second tripodal tetramine bis(3-aminopropyl)-(2-aminoethyl) amine was synthesized starting from N-acetylethylenediamine, through addition reaction with acrylonitrile, followed by hydrogenation and amidohydrolysis.3) Tri (3-aminopropyl) amine was prepared by the addition of ammonia with acrylonitrile, followed by hydrogenation.4) Two triisobutyl-substituted tetramine were obtained through the addition/reduction of excess isobutyraldehyde with bis(2-aminoethyl)-(3-aminopropyl) amine, tri(3-aminopropyl) -(2-aminoethyl) amine, respectively.To synthesize the superbase, the aforementioned disubstituted and trisubstituted tetramines recacted with phosphorus trichloride and P(NEt2)3 (HEPT) in acetonitrile, affording the corresponding superbase salts,which then were converted to the corresponding superbases by dehydrohalogenation.It was also found that the tetramine tri (3-aminopropyl) amine (trpn) could be reacted with phosphorus trichloride and HEPT to generate super-base salt directly, although its free base is not stable enough to be isolated.