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Cyclic Trimers and Tetramers with Piperazine and 2‐Butyne as Building Blocks
Author(s) -
Gleiter Rolf,
Hövermann Kirstin,
Rominger Frank,
Oeser Thomas
Publication year - 2001
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200102)2001:4<725::aid-ejoc725>3.0.co;2-i
Subject(s) - piperazine , chemistry , trimer , tetramer , ring flip , crystallography , ring (chemistry) , stereochemistry , dimer , organic chemistry , enzyme
The reaction of piperazine with 2‐butyne‐1,4‐ditosylate in a 1:1 ratio yields the cyclic trimer 7 and the cyclic tetramer 8 . 1 H NMR investigations on 7 and 8 reveal a dynamic process with Δ G ‡ = 13 kcal/mol. This process is attributed to an inversion of the piperazine rings. Single crystals of 7· CH 3 OH, 7· 2 CF 3 COOH·H 2 O and 8 have been isolated and investigated by X‐ray diffraction. In the first two cases methanol, or water and CF 3 CO 2 − , were included in the interior of the ring.