Premium
In Pursuit of cis , cis , cis ‐Cyclonona‐2,5,8‐triene‐1,4,7‐trione – An Adventure in Medium‐Sized Ring Chemistry
Author(s) -
Pleschke Axel,
Geier Jens,
Keller Manfred,
Wörth Jürgen,
Knothe Lothar,
Prinzbach Horst
Publication year - 2007
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/ejoc.200700397
Subject(s) - chemistry , protonation , ring (chemistry) , bromine , electron ionization , molecule , fragmentation (computing) , ion , medicinal chemistry , stereochemistry , ionization , organic chemistry , computer science , operating system
Attempts to synthesize the long soughtafter tris‐π‐homobenzene cis , cis , cis ‐2,5,8‐cyclononatriene‐1,4,7‐trione, via the newly prepared cyclononane‐1,4,7‐trione (C 9 H 6 O 3 ), through base‐catalysed threefold HBr elimination from an efficiently prepared and stereochemically uniform tribromo derivative, failed due to typical medium‐ring complications, transannular reactions and an exceptional ease of polymerization. In the cations generated in the vapour phase through electron‐impact ionization (MS), the threefold elimination of (H)Br, competing with the elimination of CO, led to C 9 H 7 O 3 + ions, whereas the impressively neat anionic three‐step fragmentation pathway resulted in C 9 H 6 O 3 – ion(s). Whilst the compositions of these bromine‐free ions, which were in part computationally approached {B3LYP/6‐31+G(d,p)}, and their assignments appeared compatible with the protonated and anionic target molecules, their true natures remain open. X‐ray structural analyses for several (bridged) nine‐membered ring compounds are provided. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)