2
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M. Taifur Rahman et al.
LETTER
(7) Typical Experimental Procedure for Bromination of
References
Acetophenones.
(1) (a) Gladysz, J. A.; Curran, D. P.; Horváth, I. T. In Handbook
of Fluorous Chemistry; Wiley-VCH: Weinheim, 2004.
®
Galden HT 135 (1.5 mL) was placed in a test tube, and then
bromine (320.0 mg, 2.0 mmol) was introduced slowly by
using a glass pipette. Since bromine is more dense than the
fluorous phase, bromine sank to the bottom, forming two
(
(
(
b) Horváth, I. T. Acc. Chem. Res. 1998, 31, 641.
c) Curran, D. P. Angew. Chem. Int. Ed. 1998, 37, 1175.
d) Symposium-in-Print on fluorous chemistry: Gladysz, J.
A.; Curran, D. P. Tetrahedron 2002, 58, 3823; and
succeeding papers. (e) Zhang, W. Chem. Rev. 2004, 104,
layers. A CHCl solution (1.5 mL) of 4-chloroacetophenone
3
(309.0 mg, 2.0 mmol; Table 1, run 4) was then slowly added,
which made the third layer. Then, 1.0 mL of 1 M aq solution
of K CO was added on the top, forming a four-phasic
2
531.
2
3
(2) (a) Ryu, I.; Matsubara, H.; Yasuda, S.; Nakamura, H.;
system. Then the test tube was covered with aluminum foil
to protect from light and left overnight without stirring at r.t.
After the bromine layer had disappeared and the fluorous
phase became colorless, the upper two phases (aqueous and
organic) were decanted. The organic phase was separated,
washed with aqueous solution of Na SO , dried over MgSO
4
Curran, D. P. J. Am. Chem. Soc. 2002, 124, 12964.
b) Matsubara, H.; Yasuda, S.; Ryu, I. Synlett 2003, 247.
c) Nakamura, H.; Usui, T.; Kuroda, H.; Matsubara, H.;
Yasuda, S.; Ryu, I.; Curran, D. P. Org. Lett. 2003, 5, 1167.
d) Iskra, J.; Staver, S.; Zupan, M. Chem. Commun. 2003,
(
(
(
2
3
2
3
496. (e) Jana, N. K.; Verkade, J. G. Org. Lett. 2003, 5,
787. (f) Curran, D. P.; Werner, S. Org. Lett. 2004, 6, 1021.
and concentrated. The residue was purified by a short
column chromatography (silica gel, eluted with hexane–
EtOAc) to give 420.4 mg (yield 90%) of 2-bromo-1-(4-
chlorophenyl)ethanone as colorless microcrystals.
8) In a triphasic system (aqueous phase being omitted)
bromination of acetophenone derivatives proceeded,
however, pungent HBr gas evolved from the top layer.
(3) House, H. O. In Modern Synthetic Reaction, 2nd ed.;
Benjamin, W. A., Ed.; New York, 1977, 459.
(
4) (a) Cowper, R. M.; Davidson, L. H. Org. Synth. Coll. Vol. II;
Wiley & Sons: New York, 1943, 480. (b) Garbisch, F. W.
Jr. J. Org. Chem. 1965, 30, 2109. (c) Hulme, A. N.; Henry,
S. S.; Meyers, A. J. J. Org. Chem. 1995, 60, 1265. (d) Teo,
K. E.; Warnhoff, E. W. J. Am. Chem. Soc. 1973, 95, 2728.
(
(
9) Pernía, G. J.; Kilburn, J. D.; Essex, J. W.; Mortishire-Smith,
R. J.; Rowley, M. J. Am. Chem. Soc. 1996, 118, 10220.
(
2
e) Givens, R. S.; Park, C.-H. J. Am. Chem. Soc. 1997, 119,
453.
(
10) With 1.0 equiv of Br , 44% of the dibromo-substituted arene
2
was obtained along with 43% recovery of the starting
material.
11) Barhate, N. B.; Gajare, R. D.; Wakharkar, R. D.; Bedekar, A.
V. Tetrahedron Lett. 1998, 39, 6349.
(
(
5) Yadav, J. S.; Reddy, B. V. S.; Reddy, P. S. R.; Basak, A. K.;
Narsaiah, A. V. Adv. Synth. Catal. 2004, 346, 77.
(
®
6) Galden HT135 is a polyether-type perfluorinated solvent,
which is commercially available as a heat transfer liquid
(
12) Harrison, G. C.; Diehl, H. Org. Synth. Coll. Vol. III; Wiley
(
°
Solvay Solexis Inc.). Bp 135 °C, density = 1.72 g/mL at 25
C, average molecular weight = 610. The general structure is
shown in Figure 2.
&
Sons: New York, 1955, 370.
F
F
F
F
F
O
F3C
O
OCF3
m
CF3
n
®
Galden HT135
Figure 2
Synlett 2005, No. 17, 2664–2666 © Thieme Stuttgart · New York