1238
D. Wilcke et al.
CLUSTER
with benzylic alcohol 3 (21.0 mg, 100 mmol) and indole
(2) (a) Catalytic Asymmetric Friedel–Crafts Alkylations;
Bandini, M.; Umani-Ronchi, A., Eds.; Wiley-VCH:
Weinheim, 2009. (b) Rueping, M.; Nachtsheim, B. J.
Beilstein J. Org. Chem. 2010, 6, No. 6. (c) Terrasson, V.;
Marcia de Figueiredo, R.; Campagne, J. M. Eur. J. Org.
Chem. 2010, 2635. (d) Poulsen, T. B.; Jørgensen, K. A.
Chem. Rev. 2008, 108, 2903.
(3) (a) Mühlthau, F.; Schuster, O.; Bach, T. J. Am. Chem. Soc.
2005, 127, 9348. (b) Mühlthau, F.; Bach, T. Synthesis 2005,
3428. (c) Stadler, D.; Mühlthau, F.; Rubenbauer, P.;
Herdtweck, E.; Bach, T. Synlett 2006, 2573. (d) Stadler, D.;
Bach, T. Chem. Asian J. 2008, 3, 272. (e) Stadler, D.; Bach,
T. Angew. Chem. Int. Ed. 2008, 47, 7557.
(4) (a) Mühlthau, F.; Stadler, D.; Goeppert, A.; Olah, G. A.;
Prakash, G. K. S.; Bach, T. J. Am. Chem. Soc. 2006, 128,
9668. (b) Stadler, D.; Goeppert, A.; Rasul, G.; Olah, G. A.;
Prakash, G. K. S.; Bach, T. J. Org. Chem. 2009, 74, 312.
(5) Reviews: (a) Terada, M. Synthesis 2010, 1929. (b) You,
S.-L.; Cai, Q.; Zeng, M. Chem. Soc. Rev. 2009, 38, 2190.
(c) Terada, M. Chem. Commun. 2008, 4097. (d) Akiyama,
T. Chem. Rev. 2007, 107, 5744. (e) Zamfir, A.; Schenker,
S.; Freund, M.; Tsogoeva, S. B. Org. Biomol. Chem. 2010,
8, 5262.
(46.9 mg, 400 mmol) in dry trifluorotoluene (1.5 mL).
Catalyst 7g (7.53 mg, 10 mmol) was added, and the resulting
mixture was stirred at r.t. until the starting material was
completely consumed (monitored by TLC). The crude
reaction mixture was purified directly by flash column
chromatography on silica gel (eluent: pentane–Et2O = 4:1 to
2:1) yielding compound 8 (30.9 mg, 100 mmol, quant., 50%
ee) as a light-brown solid. 1H NMR (360 MHz, CDCl3): d =
1.15 (s, 9 H), 3.71 (s, 3 H), 4.51 (s, 1 H), 5.30 (s, 1 H), 6.28
(d, 4J = 2.3 Hz, 1 H), 6.44 (dd, 3J = 8.5 Hz, 4J = 2.3 Hz, 1 H),
7.04 (virt. t, 3J = ca. 7.5 Hz, 1 H), 7.15 (virt. t, 3J = ca. 7.6
Hz, 1 H), 7.26 (d, 3J = 8.5 Hz, 1 H), 7.29 (d, 3J = 8.1 Hz, 1
H), 7.36 (d, 3J = 1.9 Hz, 1 H), 7.52 (d, 3J = 8.0 Hz, 1 H), 8.02
(br s, 1 H) ppm. 13C NMR (90.6 MHz, CDCl3): d = 28.9,
35.8, 45.4, 55.1, 101.6, 105.8, 110.8, 117.3, 119.4, 119.5,
121.2, 121.5, 122.2, 128.7, 132.1, 135.5, 154.9, 158.6 ppm.
HRMS: m/z calcd for C20H23NO2: 309.1723; found:
309.1724.
(20) An analysis of the absolute structure based on Bayesian
statistics and Friedel pairs with a coverage of 99% resulted
in a probability of 1.00.
Crystal Data
(6) Uraguchi, T.; Terada, M. J. Am. Chem. Soc. 2004, 126, 5356.
(7) Akiyama, T.; Itoh, J.; Yokota, K.; Fuchibe, K. Angew. Chem.
Int. Ed. 2004, 43, 1566.
(8) (a) Sun, F.-L.; Zeng, M.; Gu, Q.; You, S.-L. Chem. Eur.
J. 2009, 15, 8709. (b) Sun, F.-L.; Zheng, X.-J.; Gu, Q.; He,
Q.-L.; You, S.-L. Eur. J. Org. Chem. 2010, 47. (c) See also:
Rueping, M.; Nachtsheim, B. J.; Moreth, S. A.; Bolte, M.
Angew. Chem. Int. Ed. 2008, 47, 593.
Formula: C20H23NO2·C4H10O; Mr = 383.51; crystal color
and shape: colorless fragment, crystal dimensions: 0.13 ×
0.23 × 0.69 mm; crystal system: monoclinic; space group:
P21 (no. 4); a = 10.2950 (4), b = 7.7382 (3), c = 15.1602 (5)
Å, b = 104.737 (2)°; V = 1168.00(8) Å3; Z = 2;
m
MoKa = 0.071 mm–1; rcalcd = 1.090 g cm–3; q range = 1.39–
25.33°; data collected: 27134; independent data [Io > 2s (Io)/
all data/Rint]: 3857/4255/0.027; data/restraints/parameters:
4255/1/267; R1 [Io > 2s (Io)/all data]: 0.0376/0.0419; wR2
[Io > 2s (Io)/all data]: 0.1086/0.1119; GOF = 1.089; Drmax/
min: 0.11/–0.13 e Å–3; Flack parameter; x = –0.6 (13); ‘Flack
Equivalent’ Hooft parameter y = –0.3 (3). For detailed
information see Supporting Information. CCDC 808871
[(–)-8] contains the supplementary crystallographic data for
this compound. This data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via
(9) Guo, Q.-X.; Peng, Y.-G.; Zhang, J.-W.; Song, L.; Feng, Z.;
Gong, L.-Z. Org. Lett. 2009, 11, 4620.
(10) Liang, T.; Zhang, Z.; Antilla, J. C. Angew. Chem. Int. Ed.
2010, 49, 9734.
(11) For recent work on ion pairs with onium and iminium ions,
see: (a) Čorić, I.; Müller, S.; List, B. J. Am. Chem. Soc. 2010,
132, 17370. (b) Yu, X.; Lu, A.; Wang, Y.; Wu, G.; Song, H.;
Zhou, Z.; Tang, C. Eur. J. Org. Chem. 2011, 892; and
references cited therein.
(12) Nakashima, D.; Yamamoto, H. J. Am. Chem. Soc. 2006, 128,
9626.
(13) Specht, D. P.; Martic, P. A.; Farid, S. Tetrahedron 1982, 38,
1203.
(21) First example of a kinetic resolution with chiral phosphoric
acids: Enders, D.; Narine, A. A.; Toulgoat, F.; Bisschops, T.
Angew. Chem. Int. Ed. 2008, 47, 5661.
(22) Crystal Data
(14) Katritzky, A. R.; Ji, Y.; Fang, Y.; Prakash, I. J. Org. Chem.
2001, 66, 5613.
(15) Baciocchi, E.; Bietti, M.; Putignani, L.; Steenken, S. J. Am.
Chem. Soc. 1996, 118, 5952.
(16) (a) Wu, T. R.; Shen, L.; Chong, J. M. Org. Lett. 2004, 6,
2701. (b) Jacques, J.; Fouquey, C. Org. Synth. 1989, 67, 1.
(c) Storer, R. I.; Carrera, D. E.; Ni, Y.; MacMillan, D. W. C.
J. Am. Chem. Soc. 2006, 128, 84.
(17) Klussmann, M.; Ratjen, L.; Hoffmann, S.; Wakchaure, V.;
Goddard, R.; List, B. Synlett 2010, 2189.
(18) Relevant reviews: (a) Bandini, M.; Melloni, A.; Tommasi,
S.; Umani-Ronchi, A. Synlett 2005, 1199. (b) Bandini, M.;
Eichholzer, A. Angew. Chem. Int. Ed. 2009, 48, 9608.
(c) Zeng, M.; You, S.-L. Synlett 2010, 1289. (d) Bartoli, G.;
Bencivenni, G.; Dalpozzo, R. Chem. Soc. Rev. 2010, 39,
4449.
Formula: C12H18O3; Mr = 210.26; crystal color and shape:
colorless fragment, crystal dimensions: 0.46 × 0.51 × 0.61
mm; crystal system: orthorhombic; space group: P212121
(no. 19); a = 6.6950 (1), b = 9.1455 (2), c = 19.2531 (4) Å;
V = 1178.85 (4) Å3; Z = 4; mCuKa = 0.680 mm–1;
r
calcd = 1.185 g cm–3; q range = 4.59–66.30°; data collected:
27197; independent data [Io > 2s (Io)/all data/Rint]: 1984/
1995/0.027; data/restraints/parameters: 1995/0/209; R1 [Io >
2s (Io)/all data]: 0.0215/0.0216; wR2 [Io > 2s (Io)/all data]:
0.0582/0.0582; GOF = 1.111; Drmax/min: 0.13/–0.12 e Å–3;
Flack parameter; x = 0.03 (15); ‘Flack Equivalent’ Hooft
parameter y = 0.05 (3). For detailed information see
Supporting Information. CCDC 808870 [(+)-3)] contains the
supplementary crystallographic data for this compound.
This data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via
(19) Representative Procedure (8)
A Schlenk flask containing 250 mg of 4 Å MS was charged
Synlett 2011, No. 9, 1235–1238 © Thieme Stuttgart · New York