Synthesis and characterisation of unusual tetraaminoalkenes (enetetramines)

Two general routes are described for the synthesis of the title compounds from the reaction of either (A) the dimethyl acetal of N,N-dimethylformamide and an appropriate N,N′-bis(secondary amine), or (B) sodium hydride and a 4,5-dihydroimidazolium or tetrahydropyrimidinium salt. The following new compounds have been made: trans-R[graphic omitted][graphic omitted]R [R = Et and R′= Me (1a) or CH2Ph (1b)] and R[graphic omitted][graphic omitted]R [n=m= 2 and R= Me (2a) or CH2Ph (2b); n= 3, m= 2, and R= CH2Ph (3); or n= 2, m= 3, and R= CH2Ph (4)].X-Ray data on crystalline [graphic omitted]R]2(R = CH2Ph) and (2b)[data in parentheses] show a short CC bond, 1.319(8)Å[1.329(5)Å], long Csp2–N bonds, av. 1.437(11)Å[1.424(4)Å], with each of the four nitrogen atoms in a pyramidal sp3 environment.