4th EucheMs chemistry congress

Poster Session 2
s1275
chem. Listy 106, s257–s1425 (2012)
Poster session 2 - organic chemistry
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BindinG Mode infLuenCe on GAS-PhASe
frAGMentAtion of AdAMAntyLAted
BiSiMidAzoLiuM@CuCurBit[7]uriL CoMPLexeS
P. BrAnná 1 , M. rouChAL 1 , J. CernoChová 1 ,
r. víChA 1
1 Tomas Bata University in Zlin Faculty of Technology,
Department of Chemistry, Zlin, Czech Republic
Within two past decades, the host-guest chemistry of
cucurbit[n]urils (CBs) and various guests has been extensively
studied in solution as well as in the gas phase. We prepared new
adamantylated bisimidazolium (BIM) salts and examined their
binding behavior towards CB7 in the gas phase using an ion trap
instrument equipped with electrospray ion source. Two distinct
binding modes may be supposed for our systems. In the first class
of complexes, the adamantane moiety is arranged inside the
interior cavity of CB7 and only one CB7 carbonyl portal is
occupied by positively charged imidazolium ring. If it is sterically
allowed, the CB7 unit may slip over the BIM scaffold to form the
complex of the second class with both CB7 carbonyl portals
occupied by imidazolium rings. Sole BIM dications decomposed
in concert with electrostatic repulsion to produce two singly
charged fragments upon collision induced dissociation (CID)
conditions. Similarly, the complexes of BIM bearing bulky
substituents dissociated to singly charged axel residue and
aggregate of 1-adamantylmethyl cation with CB7. In contrast,
some BIMs complexed to CB7 released neutral fragment
(1-adamantylcarbene) to form doubly charged aggregate of CB7
and axel residue. Furthermore, the subsequent releasing of the
second 1-adamantylcarbene was observed. This unexpected
fragmentation occurred only when the slippage of CB7 unit over
the BIM axel is sterically allowed. This phenomenon may be
employed as an efficient tool for binding mode clarification using
mass spectrometry.
Acknowledgement: The financial support of this work by the
Internal Founding Agency of Tomas Bata University in Zlin
(project No. IGA/FT/2012/016) is gratefully acknowledged.
Keywords: gas-phase reactions; host-guest system;
4 th EucheMs chemistry congress
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trACeLeSS toSyLhydrAzone-BASed triAzoLe
forMAtion: towArdS A viABLe And roBuSt
ALternAtive for the CovALent LABeLinG of
vAriouS BioMoLeCuLeS
S. BrAuCh 1 , S. S. vAn BerKeL 2 , B. weSterMAnn 1
1 Leibniz Institute of Plant Biochemistry, Department of
Bioorganic Chemistry, Halle (Saale), Germany
2 University of Oxford, Department of Chemistry, Oxford, United
Kingdom
Traceless Tosylhydrazone-based Triazole formation (Sakai
reaction) can be readily achieved by reacting primary amines with
functional α,α-dichlorotosylhydrazones under ambient conditions.
This fast and efficient alternative to the copper-assisted azidealkyne
cycloaddition (CUAAC) and strain-promoted azide-alkyne
cycloaddition (SPAAC) affords, exclusively, 1,4-substituted
triazole “click-products” with high stereoretention. Moreover the
observed versatility and chemoselectivity of the here presented
metal-free triazole formation methodology led us to the
conclusion that primary amines, inherent to many natural products
and biomolecules, should be applicable as functional handles
for further modifications (e.g. fluorescent labeling,
biotinylation). Besides the synthesis of various functional
α,α-dichlorotosylhydrazones, first attempts regarding the
bioapplicability of the Sakai reaction will be discussed.
references:
1. K. Sakai, N. Hida, K. Kondo, Bull. Chem. Soc. Jpn. 1986,
59, 179–183.
2. S. S. van Berkel, S. Brauch, L. Gabriel, M. Henze,
S. Stark, D. Vasilev, L. A. Wessjohann, M. Abbas
B. Westermann, Angew. Chem. Int. Ed. 2012, in press,
DOI: 10.1002/anie.201108850.
Keywords: Click Chemistry; Heterocycles; Hydrazones;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc