Table 2 Intramolecular Ir-catalysed allylic alkylations of carbonates
6 and 7 according to Scheme 3a
Notes and references
1 (a) B. M. Trost and C. Lee, in Catalytic Asymmetric Synthesis, ed.
I. Ojima, Wiley, New York, 2000, 2nd edn., p. 593; (b) A. Pfaltz and
M. Lautens, in Comprehensive Asymmetric Catalysis I–III, ed.
E. N. Jacobsen, A. Pfaltz and H. Yamamoto, Springer, Berlin, 1999,
p. 833; (c) B. M. Trost and M. L. Crawley, Chem. Rev., 2003, 103, 2921.
2 (a) B. Bartels and G. Helmchen, Chem. Commun., 1999, 741; (b)
B. Bartels, C. Garcia-Yebra, F. Rominger and G. Helmchen, Eur.
J. Inorg. Chem., 2002, 2569; (c) G. Lipowsky, N. Miller and
G. Helmchen, Angew. Chem., Int. Ed., 2004, 43, 4595; (d)
G. Lipowsky and G. Helmchen, Chem. Commun., 2004, 116; (e)
A. Alexakis and D. Polet, Org. Lett., 2004, 6, 3529; (f) K. Tissot-Croset,
D. Polet and A. Alexakis, Angew. Chem., Int. Ed., 2004, 43, 2426.
3 (a) C. Welter, O. Koch, G. Lipowsky and G. Helmchen, Chem.
Commun., 2004, 896; (b) A. Leitner, C. Shu and J. F. Hartwig, Proc.
Natl. Acad. Sci. USA, 2004, 101, 5930; (c) C. Shu, A. Leitner and
J. F. Hartwig, Angew. Chem., Int. Ed., 2004, 43, 4797.
Yieldb Ee (%)c
Entry Substrate Ligand Product
(%)
(Abs. Conf.)
1
2
3
4
5
6
L1
L2
L3
L4
L5
68
77
81
74
78
85 (R)
96 (R)
93 (R)
91 (R)
86 (R)
6
7
8
9
10
7
L1
L2
L3
L4
L5
71
79
83
73
67
89 (R)
97 (R)
95 (R)
95 (R)
87 (R)
4 (a) F. Lopez, T. Ohmura and J. F. Hartwig, J. Am. Chem. Soc., 2003,
125, 3426; (b) Kinetic resolution: C. Fischer, C. Defieber, T. Suzuki and
E. M. Carreira, J. Am. Chem. Soc., 2004, 126, 1628.
5 The world market prices per ounce (October 2003) are: rhodium $500,
palladium $199, iridium $90.
6 Survey: B. L. Feringa, Acc. Chem. Res., 2000, 33, 346.
7 B. Bartels, C. Garcia-Yebra and G. Helmchen, Eur. J. Org. Chem.,
2003, 1097.
a
All reactions were carried out on a 0.5 mmol scale using conditions C
with 2 mol% of [Ir(COD)Cl]2, 4 mol% of ligand and 2 h of activation
with TBD (8 mol%). See ESI for experimental procedures. Yield of
b
c
isolated product.
b-cyclodextrin, Cp-Cyclodextrin-B-236-M-19 (25
120 uC isothermal, injection temp. 200 uC, tR[(S)-8] 5 11.2 min,
tR[(R)-8] 5 11.5 min, tR[(S)-9] 5 18.5 min, tR[(R)-9] 5 19.2 min).
Determined by GC (Chrompack permethyl
0.25 mm),
m 6
8 Other ligands probed have been phosphites (cf. N. Kinoshita,
K. H. Marx, K. Tanaka, K. Tsubaki, T. Kawabata, N. Yoshikai,
E. Nakamura and K. Fuji, J. Org. Chem., 2004, 69, 7960 and literature
cited therein); phosphinooxazolines (ref. 3a) and Pybox (H. Miyabe,
A. Matsumura, K. Moriyama and Y. Takemoto, Org. Lett., 2004, 6,
4631).
9 TBD: 1,5,7-triazabicyclo[4.4.0]dec-5-ene; DABCO: 1,4-diazabicyclo-
[2.2.2]octane.
10 C. A. Kiener, C. Shu, C. Incarvito and J. F. Hartwig, J. Am. Chem.
Soc., 2003, 125, 14272.
11 P. A. Evans et al. have reported a similar regioselective but not
enantioselective Rh-catalysed allylic alkylation, using alkenylmalonates
as nucleophiles, followed by RCM to furnish monocyclic carbocycles:
(a) P. A. Evans and L. J. Kennedy, Tetrahedron Lett., 2001, 42, 7015; see
also B. M. Trost and C. Jiang, Org. Lett., 2003, 5, 1563. An asymmetric
Cu-catalysed allylic substitution/RCM sequence was reported by the
Alexakis group: K. Tisot-Croset, D. Polet, S. Gille, C. Hawner and
A. Alexakis, Synthesis, 2004, 2586.
12 Cl2(PCy3)2RuLCHPh, cf. P. Schwab, M. B. France, J. W. Ziller and
R. H. Grubbs, Angew. Chem., Int. Ed. Engl., 1995, 34, 2039.
13 In this case, use of procedure D did not lead to improvement.
14 C. Welter, A. Dahnz, B. Brunner, S. Streiff, P. Du¨bon and G. Helmchen,
Org. Lett., 2005, 7, 1239.
In conclusion, improved reaction conditions for Ir-catalysed
allylic alkylations based on the use of known and new phosphorus
amidite ligands derived from 1-(2-methoxyphenyl)ethylamine were
developed. Unsaturated carbocycles were prepared via allylic
alkylation with sodioalkenylmalonates followed by ring closing
metathesis. In addition, the first Ir-catalysed intramolecular allylic
alkylations are reported.
This
work
was
supported
by
the
Deutsche
Forschungsgemeinschaft (SFB 623), the Degussa-Stiftung and
the Fonds der Chemischen Industrie. We thank Markus Krauter
for competent experimental assistance, Degussa AG for iridium
salts, Dr G. Egri (Reuter Chemischer Apparatebau KG) for
(S)-BINOL and Dr K. Ditrich (BASF AG) for enantiomerically
pure 2-arylethylamines.
Stephane Streiff, Carolin Welter, Mathias Schelwies, Gunter Lipowsky,
Nicole Miller and Gu¨nter Helmchen*
Organisch-Chemisches Institut der Ruprecht-Karls-Universita¨t
Heidelberg, Im Neuenheimer Feld 270, 69207, Heidelberg, Germany.
E-mail: g.helmchen@urz.uni-heidelberg.de; Fax: +49 6221 544205;
Tel: +49 6221 548401
15 G. Helmchen and A. Pfaltz, Acc. Chem. Res., 2000, 6, 336.
16 8: G. Koch and A. Pfaltz, Tetrahedron: Asymmetry, 1996, 7, 2213; 9:
M. Peer, Dissertation, Universita¨t Heidelberg, Heidelberg, Germany,
1996.
This journal is ß The Royal Society of Chemistry 2005
Chem. Commun., 2005, 2957–2959 | 2959