Chemistry Letters Vol.32, No.8 (2003)
731
less colorless sticky liquid with the dynamic viscosity
m ¼ 160 cP (0.01 gꢄcmÀ1ꢄsÀ1, on a CV-100 Caulking Visco-
meter at 20 ꢁC, estimated error: ꢅ2%), The liquid solidified
at 16 ꢁC to give 1 as a colorless waxy solid. Anal. Calcd for
C12H30B11N (307.300): C, 46.90; H, 9.84; N, 4.56. Found:
C, 46.83; H, 9.80; N, 4.52%. 1H NMR (CDCl3, ppm): d
8.74 (d, 2H, 2 N-CPy-H), 7.62 (d, 2H, CPy-H), 4.46 (t, 2H,
N-CH2-), 2.41 (s, 3H, CPy-CH3), 1.75 (m, 2H, N-C-CH2-),
0.95 (m, 4H, N-C-C-CH2-CH2-), 0.61 (t, 3H, -CH3), 0.20-
2.20 (m, 12H, 11 BH and CcageH). 13C NMR (CDCl3, ppm):
d 13.78 (C-C-C-C-C-N), 22.05 (C-C-C-C-C-N or CH3-CPy),
22.31 (C-C-C-C-C-N, or CH3-CPy), 28.01 (C-C-C-C-C-N),
29.64 (Ccage), 31.36 (C-C-C-C-C-N), 61.44 (C-C-C-C-C-N),
129.13 (CPy), 143.73 (CPy), 159.33 (CPy). IR (KBr pellet,
cmÀ1): 3416 (br, s), 2955 (s, s), 2927 (s, vs), 2858 (s, s),
2538 (vs, s, ꢀB-H), 1641 (s, s), 1572 (s, w), 1517 (s, m),
1468 (s, s), 1379 (s, w), 1173 (s, m), 1016 (br, m), 946 (s,
w), 826 (s, s), 723 (s, m), 554 (s, w).
arenes mediated with manganese(III) acetate. The superior per-
formance of this system warrants further mechanistic studies,
which are currently underway in our laboratories.
Table 1. Synthesis of arylacetones
O
Mn(OAc)3
O
R
+
Solvent, ((((
R
R
Yielda
/%, total
Time
/h
Product distribution
ortho-/meta-/para-%
Me
A86, B84, 1.5
C93, Db51,
Ac75
A80.4/8.7/10.9 B76.3/6.2/17.5
C84.7/2.8/12.5 Db66.0/19.0/15.0
Ac77.2/11.3/11.5
NO2 A62, B68, 2.0
C77, D23
A83.3/4.8/11.9 B86.0/2.7/11.3
C96.3/1.2/2.5 D73.4/13.6/13.0
A85.7/5.1/9.2 B82.9/6.8/10.3
C94.1/1.8/4.1 Db72.1/6.0/21.9
A71.8/13.7/14.5 B65.7/16.1/18.2
C77.9/8.7/13.4 D68.9/17.4/13.7
Cl
A64, B67, 1.5
C79, Db25
tBu A82, B87, 2.0
11 A. S. Larsen, J. D. Holbrey, F. S. Tham, and C. A. Reed, J.
Am. Chem. Soc., 122, 7264 (2000).
12 Synthesis of arylacetone. In a typical reaction to prepare phe-
nylacetone, a mixture of manganese(III) acetate dihydrate
(0.80 g, 2.87 mmol), benzene (3.5 mL), acetone (3.5 mL) and
ionic liquid 10.0 mL was irradiated with by ultrasound (ultra-
sonic frequency 50 kHz) for 1.5 h with continuous stirring un-
der argon atmosphere. The dark brown color of manganese
(III) acetate changed to the pale pink of manganese(II) acetate
smoothly. At the end of this time, 2.0 mL methanol was added
to the vessel to trapthe reaction. The reaction mixture was
fractionatedly distilled at 1 atmospheric pressure to recover
unreacted benzene and the residue was extracted with dry di-
ethyl ether (2 ꢆ 20 mL). The ether layer was separated and
washed with 20.0 mL Na2CO3 to remove any trace of acetic
acid (this process only for the case of acetic acid solvent
was used). The ether was then dried over anhydrous MgSO4
and the solvent was evaporated in vacuum. The residue was
subjected to high vacuum distillation to remove any trace of
ionic liquid solvent, the 86-87 ꢁC/6.0 mmHg fraction was col-
lected for phenylacetone to give the 1H NMR pure phenylace-
tone 0.16 g (83% yield) when [PPI][CB11H12] was used as sol-
vent. In [BMIM][PF6] and [OMIM][BF4], the yield was 73%
and 79%, respectively. For substituted arylacetones, the re-
sulting clear product mixture after high vacuum distillation
process was subjected to HPLC-MS to determine the product
yield and distribution. The detail HPLC conditions are: col-
umn ZORBAX SB-C18, 25 cm ꢆ 0:46 cm ꢆ 3:5 mm, flow rate
1.0 mL/min, temperature 25 ꢁC, pressure 1680 psi, mobile
phase acetonitrile/methanol (v/v = 9/1). The peak identity
was confirmed by HPLC-MS and internal standard. Retention
time (mins) and main MS peaks (m=z, abundance) of substitut-
C91, D53
aA = in [BMIM][PF6], B = in [OMIM][BF4], C = in
[PPI][CB11H12], D = in acetic acid. The product distribution
was measured with HPLC-MS (in a ZORBAX SB-C18 column)
as well as 1H NMR. bRef. 2 results. cIn A without ultrasonic ir-
radiation.
This research was supported by a grant in the Institute of
Chemical and Engineering Sciences Ltd, Singapore.
References and Notes
1
2
A. Allen and T. S. Cantrell, Forensic Sci. Int., 42, 183 (1989).
M. E. Kurz, V. Baru, and P.-N. Nguyen, J. Org. Chem., 49,
1603 (1984).
3
a) Y. Zhu, C. Chibun, K. Carpenter, X. Rong, S. Selvaratnam,
N. S. Hosmane, and J. A. Maguire, Appl. Organomet. Chem.,
17, 346 (2003). b) Z. Yinghuai, S. Bahnmueller, C. Chilbin,
K. Carpenter, N. S. Hosmane, and J. A. Maguire, Tetrahedron
Lett., 44, 5473 (2003).
4
5
T. Welton, Chem. Rev., 99, 2071 (1999).
P. Wasserscheid and W. Keim, Angew. Chem., Int. Ed. Engl.,
39, 3772 (2000).
6
H. Yorimitsu and K. Oshima, Bull. Chem. Soc. Jpn., 75, 853
(2002).
7
8
C. A. Reed, Acc. Chem. Res., 31, 133 (1998).
F. Neve, A. Crispini, S. Armentano, and O. Francescangeli,
Chem. Mater., 10, 1904 (1998).
9
a) A. Franken, B. T. King, J. Rudolph, P. Rao, B. C. Noll, and
J. Michl, Collect. Czech. Chem. Commun., 66, 1238 (2001). b)
J. Plesek, T. Jelinek, E. Drdakova, S. Hermanek, and B. Stibr,
Collect. Czech. Chem. Commun., 49, 1559 (1984).
ed phenylacetone as follow: (1) Methylphenylacetone, tortho
=
13.8, tmeta = 16.1, tpara = 18.8, m=z = 148.0 (9), 105.0 (31),
43.0 (100), 15.0 (17), (2) Nitrophenylacetone, tortho = 7.3,
tmeta = 11.2, tpara = 14.6, m=z = 179.0 (100), 136.0 (42),
91.0 (41), 77.0 (8), 43.0 (87), 30.0 (17), (3) Chlorophenylace-
tone, tortho = 9.2, tmeta = 13.4, tpara = 16.4, m=z = 170.0 (11),
168.0 (35), 127.0 (15), 125.0 (46), 91.0 (18), 43.0 (100), (4)
10 All synthetic procedures were carried out in argon atmosphere
with standard Schlenk techniques. A 1.30 g (5.32 mmol) 2 dis-
solved in dry CH2Cl2 (24.0 mL) was added to a stirred solu-
tion of Cs[CB11H12] (1.50 g, 5.44 mmol) in 110.0 mL dry
methanol. The mixture was stirred at room temperature for
24 h and then all solvents were evaporated under reduced pres-
sure. The resulting viscous residue was dissolved in CH2Cl2
and purified by column chromatograph (SiO2), CH2Cl2/Di-
ethyl ether (v/v = 4/1) as the movable phase. Removal of
the solvent under reduced pressure and drying under high vac-
uum for 2.5 days resulted in 1.54 g (94% yield) of [N-n-Pen-
tyl-4-picolinium]þ[closo-CB11H12]À (1) isolated as a color-
tert-Butylphenylacetone, tortho = 12.4, tmeta = 14.7, tpara
17.3, m=z = 190.0 (7), 147.0 (11), 43.0 (100), 15.0 (18).
13 K. W. Jr. Street, J. Liq. Chromatogr., 10, 655 (1987).
=
14 P. Strazzolini, A. G. Giumanini, and A. Runcio, Tetrahedron
Lett., 42, 1387 (2001).
15 G. Midgley and C. B. Thomas, J. Chem. Soc., Perkin Trans. 2,
1984, 1537.
Published on the web (Advance View) July 14, 2003; DOI 10.1246/cl.2003.730