Synlett 2004(9): 1545-1548  
DOI: 10.1055/s-2004-829078
LETTER
© Georg Thieme Verlag Stuttgart · New York

Fluorous Columns are Superior to Cyclodextrin Columns for Demixing in Fluorous Mixture Synthesis: When and Why to Use Fluorous Silica Gel

Dennis P. Curran*, Sivaraman Dandapani, Stefan Werner, Masato Matsugi
Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
Fax: +1(412)6249861; e-Mail: curran@pitt.edu;
Further Information

Publication History

Received 23 March 2004
Publication Date:
29 June 2004 (online)

Abstract

Measurements of retention times of assorted fluorous and non-fluorous compounds on both fluorous (FluoroFlash PF-C8) and cyclodextrin (Sumichiral OA 7500) columns show that the fluo­rous column is superior to the cyclodextrin column for separating fluorous compounds. Guidelines for when and why to use fluorous columns are suggested.

5

The fluorous esters (1c, 1d, and 1e) have been already reported by Mikami (ref. 4). The fluorous anilides 3a and 3b are commercially available from Akos or Ambinter. Selected data for the new compounds follow:
3c: colorless oil. 1H NMR: δ = 7.29 (1 H, t), 7.42 (2 H, t), 7.58 (2 H, d), 7.9 (1 H, br s). 19F NMR: -124.9 (2 F), -121.5 (2 F), -121.0 (2 F), -120.4 (10 F), -118.0 (2 F), -79.5 (3 F).
6by: colorless oil. 1H NMR: δ = 0.88 (3 H, t, J = 6.6 Hz), 1.31-1.65 (8 H, m), 2.68 (2 H, t, J = 7.5 Hz), 4.82 (2 H, t, J = 13.3 Hz), 7.32 (2 H, d, J = 8.2 Hz), 7.98 (2 H, d, J = 8.1 Hz). 19F NMR: -124.9 (2 F), -122.0 (2 F), -121.5 (2 F),
-120.8 (4 F), -118.0 (2 F), -79.5 (3 F). HRMS: Calcd for C21H19F15O2: 588.1127. Found: 588.1146.
6cz: colorless oil. 1H NMR: δ = 1.25-1.89 (10 H, m), 2.59 (1 H, br s), 4.80 (2 H, t, J = 13.2 Hz), 7.32 (2 H, d, J = 8.3 Hz), 7.98 (2 H, d, J = 8.2 Hz). 19F NMR: -124.9 (2 F), -122.0 (2 F), -121.5 (2 F), 120.6 (8 F), -118.0 (2 F), -79.5 (3 F) ppm. HRMS: Calcd for C23H17F19O2: 686.0921. Found: 686.0925.
6az: colorless oil. 1H NMR: δ = 1.25-1.89 (10 H, m), 2.59 (1 H, br s), 4.80 (2 H, t, J = 13.2 Hz), 7.32 (2 H, d, J = 8.3 Hz), 7.98 (2 H, d, J = 8.3 Hz) ppm. 19F NMR: -126.4 (2 F),
-119.1 (2 F), -79.6 (3 F) ppm. HRMS: Calcd for C17H17F7O2: 386.1129. Found: 386.1117.