4642
S. Arai et al. / Tetrahedron 61 (2005) 4639–4642
AgClO4 (12.4 mg, 0.06 mmol, 3 mol%), nitromethane
2.0 mL) was added under argon atmosphere and then
mixture was stirred for 10 min at room temperature. Then
Matsumoto, T.; Morooka, M.; Ohba, S.; Suzuki, K. Synlett
1992, 340–342.
(
4. Arai, S.; Sudo, Y.; Nishida, A. Synlett 2004, 1104–1106.
5. For a review of the Friedel–Crafts reaction, see: (a) Olah,
G. A.; Friedel-Crafts Chemistry; Wiley-Interscience: London,
1973. (b) Heaney, H. In Comprehensive Organic Synthesis;
Trost, B. M., Fleming, I., Eds.; Pergamon: Oxford, 1991;
p 733.
1
a (0.24 mL, 2.0 mmol) and acetic anhydride (0.28 mL,
.0 mmol) were added at room temperature. After the
3
mixture was stirred for 1.5 h at 80 8C, the reaction was
quenched with sat. NaHCO (1.0 mL). The mixture was
3
extracted with CH Cl (5 mL, 3 times), washed with brine,
2
2
dried over Na SO and concentrated in vacuo. Purification
2
by flash column chromatography on silica gel (hexane:
AcOEtZ2:1) gave 2a as a colorless oil (326.6 mg,
6. Catalytic Friedel–Crafts acylations using less reactive sub-
strates are reported. See: (a) Kobayashi, S.; Iwamoto, S.
Tetrahedron Lett. 1998, 39, 4697–4700. (b) Earle, M. J.;
Hakala, U.; McAuley, B. J.; Nieuwenhuyzen, M.; Ramani, A.;
Seddon, K. R. Chem. Commun. 2004, 1368–1369.
4
1
.81 mmol, 91%).
3
.2. Typical experimental procedure for Sakurai–
(
c) Desmurs, J. R.; Labrouill e` re, M.; Roux, C. L.; Gaspard,
H.; Laporterie, A.; Dubac, L. J. Tetrahedron Lett. 1997, 38,
871–8874. (d) Singh, R. P.; Kamble, R. M.; Chandra, K. L.;
Saravanan, C. P.; Singh, V. K. Tetrahedron 2001, 57,
41–247. (e) Hwang, J. P.; Prakash, G. K. S.; Olah, G. A.
Hosomi reaction of acetal 4, synthesis of 6a (Table 3,
entry 3)
8
To a mixture of NbCl (1.4 mg, 0.005 mmol, 0.5 mol%) and
5
AgClO4 (1.0 mg, 0.005 mmol, 0.5 mol%) in CH Cl2
2
2
Tetrahedron Lett. 2000, 56, 7199–7203. (f) Chapman, C. J.;
Frost, C. G.; Hartley, J. P.; Whittle, A. J. Tetrahedron Lett.
(
(
1.0 mL) was added 4a (150 mL, 1.0 mmol) and 5
191 mL, 1.2 mmol) at 0 8C. After stirring for 10 min, the
2
001, 42, 773–775. (g) Matsuo, J.-I.; Odashima, K.;
reaction was quenched by addition of saturated NaHCO3
1.0 mL) and the resulting mixture was extracted with
CH Cl (5 mL three times). The combined organic layers
Kobayashi, S. Synlett 2000, 403–405. (h) Hachiya, I.;
Moriwaki, M.; Kobayashi, S. Bull. Chem. Soc. Jpn. 1995,
(
2
2
6
8, 2053–2060.
were washed with brine, dried over Na SO and concen-
4
trated under reduced pressure. The obtained crude residue
was purified by the following flash column chromatography
2
7
. Rare earth metal triflates are also efficient catalyst in Friedel–
Crafts acylation, see: Kawada, A.; Mitamura, S.; Matsuo, J.-I.;
Tsuchiya, T.; Kobayashi, S. Bull. Chem. Soc. Jpn. 2000, 73,
(
hexane:Et OZ10:1) to give 6a as a colorless oil (141.2 mg,
2
2
325–2333 and references cited therein.
. For examples of the NbCl -promoted Friedel–Crafts reaction,
see: Segi, M.; Nakajima, T.; Suga, S. Bull. Chem. Soc. Jpn.
980, 53, 1465–1466. Ref. 4.
. According to Mukaiyama’s report, GaCl
0
.87 mmol, 87%).
8
5
1
Acknowledgements
9
3
with a silver salt was
one of the most efficient systems in catalytic Friedel–Crafts
acylation. See: (a) Mukaiyama, T.; Ohno, T.; Nishimura, T.;
Suda, S.; Kobayashi, S. Chem. Lett. 1991, 1059–1062. Various
metals with silver salts catalyzed Friedel–Crafts acylation, see:
S.A. is grateful to Chugai Award in Synthetic Chemistry,
Japan for providing financial support.
(
b) Harada, T.; Ohno, T.; Kobayashi, S.; Mukaiyama, T.
Synthesis 1991, 1216–1220. (c) Suzuki, K.; Kitagawa, H.;
Mukaiyama, T. Bull. Chem. Soc. 1993, 66, 3729–3734.
References and notes
(
d) Fulstner, A.; Voigtl a¨ nder, D.; Schrander, W.; Giebel, D.;
1
. (a) Maeta, H.; Nagasawa, T.; Handa, Y.; Takei, T.; Osamura,
Y.; Suzuki, K. Tetrahedron Lett. 1995, 36, 899–902.
Reetz, M. T. Org. Lett. 2001, 3, 417–420.
1
0. (a) Ishihara, K.; Kubota, M.; Kurihara, H.; Yamamoto, H.
J. Org. Chem. 1996, 61, 4560–4567. Other examples of direct
use of carboxylic acids in Friedel–Crafts acylation. See:
(
b) Yamamoto, M.; Nakazawa, M.; Kishikawa, K.; Kohmoto,
S. Chem. Commun. 1996, 2353–2354. (c) Howarth, J.;
Gillespie, K. Tetrahedron Lett. 1996, 37, 6011–6012.
(
b) Kawamura, M.; Cui, D.-M.; Hayashi, T.; Shimada, S.
(
d) Andrade, C. K. Z.; Azevedo, N. R. Tetrahedron Lett.
001, 42, 6473–6476. (e) Andrade, C. K. Z.; Motos, R. A. F.
Tetrahedron Lett. 2003, 44, 7715–7717. (c) Firouzabadi, H.;
Iranpoor, N.; Nowrouzi, F. Tetrahedron Lett. 2003, 44,
2
Synlett 2003, 1189–1191. (f) Ortiz, A.; Quintero, L.;
Hern a´ ndez, H.; Maldonado, S.; Mendoza, G.; Bern e` s, S.
Tetrahedron Lett. 2003, 44, 1129–1132.
5
343–5345. (d) Chiche, B.; Finiels, A.; Gauthier, C.; Geneste,
P.; Graille, J.; Pioch, D. J. Org. Chem. 1986, 51, 2128–2130
and Refs. 1b and 9c.
2
. (a) Guo, Q.; Miyaji, T.; Hara, R.; Shen, B.; Takahashi, T.
Tetrahedron 2002, 58, 7327–7334. (b) Quite recently.
Kobayashi and co-workers reported a successful example of
catalytic asymmetric carbon–carbon bond-forming reaction
using a chiral Nb(V) alkoxide, see: Kobayashi, S.; Arai, K.;
Shimizu, H.; Ihori, Y.; Ishitani, H.; Yamashita, Y. Angew.
Chem., Int. Ed. 2005, 43, 761–764.
1
1. For recent examples of the metal-catalyzed Sakurai–Hosomi
reaction using acetals, see: (a) Watahiki, T.; Akabane, Y.;
Mori, S.; Oriyama, T. Org. Lett. 2003, 5, 3045–3048.
(b) Wieland, L. C.; Zerth, H. M.; Mohan, R. S. Tetrahedron
Lett. 2002, 43, 4597–4600. (c) Yadav, J. S.; Subba, B. V.;
Srihari, P. Synlett 2001, 673–675.
3
. (a) Suzuki, K.; Hashimoto, T.; Maeta, H.; Matsumoto, T.
Synlett 1992, 125–128. (b) Hashimoto, T.; Maeta, H.;
12. For the stoichiometric reaction of 5 with benzaldehyde
promoted by NbCl , see Ref. 1a.
5