Figure 2. Asymmetric diamination of diene 7a with selected
monophosphorus and nitrogen-containing ligands.18
Figure 1. Proposed catalytic cycle for Cu(I)-catalyzed diamination.
commercially available chiral bisphosphine ligands17 were
subsequently studied for the diamination of trans-1-phe-
nylbutadiene (7a) with a 2/1 ratio of CuCl and ligand. It
was found that steric bulkiness on the phosphine atoms had
a large impact on the enantioselectivities (Figure 3). En-
easily prepared chiral monophosphorus and nitrogen-contain-
ing ligands16 and trans-1-phenylbutadiene (7a) as a test
Scheme 2
substrate at room temperature for 6 h (Scheme 2). As shown
in Figure 2, all the reactions went smoothly to give
diamination product 3a with high conversions, but with 0 to
12% ee. To search for more promising ligands, a series of
(7) For Pd(0)-catalyzed intermolecular diamination, see: (a) Du, H.;
Zhao, B.; Shi, Y. J. Am. Chem. Soc. 2007, 129, 762. (b) Xu, L.; Du, H.;
Shi, Y. J. Org. Chem. 2007, 72, 7038. (c) Du, H.; Yuan, W.; Zhao, B.; Shi,
Y. J. Am. Chem. Soc. 2007, 129, 7496.
(8) For Cu(I)-catalyzed intermolecular diamination, see: (a) Yuan, W.;
Du, H.; Zhao, B.; Shi, Y. Org. Lett. 2007, 9, 2589. (b) Zhao, B.; Yuan, W.;
Du, H.; Shi, Y. Org. Lett. 2007, 9, 4943. (c) Zhao, B.; Du, H.; Shi, Y. Org.
Lett. 2008, 10, 1087.
Figure 3. Asymmetric diamination of diene 7a with selected
bisphosphine ligands.19
(9) For leading references on asymmetric diamination using bisimi-
doosmium as reagent, see: (a) Mun˜iz, K.; Nieger, M. Synlett 2003, 211.
(b) Mun˜iz, K.; Nieger, M. Chem. Commun. 2005, 2729.
(10) (a) Du, H.; Yuan, W.; Zhao, B.; Shi, Y. J. Am. Chem. Soc. 2007,
129, 11688. (b) Xu, L.; Shi, Y. J. Org. Chem. 2008, 73, 749. (c) Du, H.;
Zhao, B.; Shi, Y. J. Am. Chem. Soc. 2008, 130, 8590.
couragingly, the diamination of 7a with (R)-DTBM-SEG-
PHOS (L12)17f gave 90% conversion and 56% ee (Figure
3).
To improve the enantioselectivity, the reaction conditions,
including solvent, temperature, and the ratio of ligand and
(11) Greene, F. D.; Stowell, J. C.; Bergmark, W. R. J. Org. Chem. 1969,
34, 2254.
(12) For a leading review on diaziridinone, see: Heine, H. W. In The
Chemistry of Heterocyclic Compounds; Hassner, A., Ed.; John Wiley &
Sons, Inc.: Hoboken, NJ, 1983; p 547.
(13) For a leading review on metal-promoted radical reactions, see: Iqbal,
J.; Bhatia, B.; Nayyar, N. K. Chem. ReV. 1994, 94, 519.
(17) For leading references on L7-L12, see: (a) Kagan, H. B.; Dang,
T.-P. J. Am. Chem. Soc. 1972, 94, 6429. (b) Miyashita, A.; Yasuda, A.;
Takaya, H.; Toriumi, K.; Ito, T.; Souchi, T.; Noyori, R. J. Am. Chem. Soc.
1980, 102, 7932. (c) Mashima, K.; Matsumura, Y.-i.; Kusano, K.-h.;
Kumobayashi, H.; Sayo, N.; Hori, Y.; Ishizaki, T.; Akutagawa, S.; Takaya,
H. J. Chem. Soc., Chem. Commun. 1991, 609. (d) Lipshutz, B. H.; Noson,
K.; Chrisman, W. J. Am. Chem. Soc. 2001, 123, 12917. (e) Hatano, M.;
Terada, M.; Mikami, K. Angew. Chem., Int. Ed. 2001, 40, 249. (f) Lipshutz,
B. H.; Lower, A.; Noson, K. Org. Lett. 2002, 4, 4045.
(14) For leading reviews on CuX-catalyzed atom transfer reactions see:
(a) Patten, T. E.; Matyjaszewski, K. Acc. Chem. Res. 1999, 32, 895. (b)
Clark, A. J. Chem. Soc. ReV. 2002, 31, 1.
(15) For a leading review on nitrogen-centered radicals, see: Stella, L.
In Radicals in Organic Synthesis; Renaud, P., Sibi, M. P., Eds.; Wiley-
VCH: Weinheim, Germany, 2001; Vol. 2, p 407.
(16) For leading references on L1-L6, see: (a) Hattori, T.; Shijo, M.;
Kumagai, S.; Miyano, S. Chem. Express 1991, 6, 335. (b) Ref 10a. (c)
Sewald, N.; Wendisch, V. Tetrahedron: Asymmetry 1998, 9, 1341. (d)
Hayashi, T.; Yamamoto, K.; Kumada, M. Tetrahedron Lett. 1974, 15, 4405.
(e) von Matt, P.; Pfaltz, A. Angew. Chem., Int. Ed. Engl. 1993, 32, 566. (f)
Evans, D. A.; Woerpel, K. A.; Hinman, M. M.; Faul, M. M. J. Am. Chem.
Soc. 1991, 113, 726. (g) Lowenthal, R. E.; Masamune, S. Tetrahedron Lett.
1991, 32, 7373.
(18) The reactions were carried out with trans-1-phenylbutadiene (0.20
mmol), di-tert-butyldiaziridinone (2) (0.30 mmol), CuCl (0.02 mmol), and
ligand L1-L5 (0.02 mmol), except for L6 (0.01 mmol) in benzene-d6 (0.60
mL) at room temperature for 6 h. The conversions were determined by
1
crude H NMR, and the ee’s were determined by chiral HPLC.
(19) The same conditions as ref 18 except for L7-L12 (0.01 mmol).
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