Greener fluorous chemistry: Convenient preparation of new types of 'CF 3-rich' secondary alkyl mesylates and their use for the synthesis of azides, amines, imidazoles and imidazolium salts

Anikó Nemes, László Tölgyesi, Andrea Bodor, József Rábai, Dénes Szabó

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

2,2,2-Trifluoroethanol, 1,1,1,3,3,3-hexafluoro-2-propanol, and nonafluoro-tert-butyl alcohol were used as precursors for the preparation of the appropriate bis(polyfluoroalkoxymethyl)carbinols [(RFHOCH 2)2CHOH, 1a-c, RFH = (a) CF3CH 2, (b) (CF3)2CH, and (c) (CF3) 3C] and the corresponding mesylates [(RFHOCH 2)2CHOSO2CH3, 2a-c]. This novel design paradigm is introduced to eliminate the persistence and bioaccumulation problems of fluorous chemistry, which are associated with the use of longer linear perfluoroalkyl groups (e.g. Rfn ≥ n-C8F 17, n-C7F15). Secondary mesylates 2a,b and the primary tosylate [(CF3)3COCH2CH2OTs, 2d] displayed acceptable reactivity towards azide and imidazole nucleophiles to allow the syntheses of novel fluorous azides, which on hydrogenolysis with H2/Pd-C offered fluorous amines [(RFHOCH2) 2CHNH2, 8a,b], and 1-(polyfluoroalkyl)imidazoles (5a,b,d), respectively, while 2c showed no reactivity due to steric hindrance. The reaction of 8a,b with formaline, glyoxal and hydrochloric acid gave symmetrical 1,3-dialkylated imidazolium chlorides (9a,b), while 5a,b,d were effectively alkylated using n-C8F17(CH2)3I, methyl iodide, 2-bromoethanol, and 2d to yield the corresponding 1,3-dialkylimidazolium iodides, bromides, and tosylates (7aa-ec). Some physical properties of new compounds including mp, bp and solubility patterns were also analyzed; and the fluorophilicity values of 1a-c, and 2a-c were experimentally determined by GC and/or 19F NMR spectroscopy.

Original languageEnglish
Pages (from-to)1368-1376
Number of pages9
JournalJournal of Fluorine Chemistry
Volume131
Issue number12
DOIs
Publication statusPublished - Dec 1 2010

Keywords

  • Alkylation
  • Fluorous imidazolium salts
  • Fluorous secondary carbinols
  • Fluorous secondary mesylates

ASJC Scopus subject areas

  • Biochemistry
  • Environmental Chemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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