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Ph
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N
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N
References and notes
O
O
Ph
O
N
N
N
O
a
HO
O
HO
1. (a) Chiral Auxiliaries and Ligands in Asymmetric Synthesis; Seyden-Penne, J., Ed.;
Wiley Interscience: New York, 1995; (b) Comprehensive Asymmetric Catalysis;
Jacobsen, E. N., Pfaltz, A., Yamamoto, H., Eds.; Springer: Berlin, 1999; Vol. I–III,
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N
N
Pd
P
Ph
Cl
Ph
PPh2
16
8
3. (a) Bertelsen, B.; Jorgensen, K. A. Chem. Soc. Rev. 2009, 38, 2178; (b) Melchiore,
P.; Marigo, M.; Carlone, A.; Bartoli, G. Angew. Chem., Int. Ed. 2008, 47, 6138; (c)
Dondoni, A.; Massi, A. Angew. Chem., Int. Ed. 2008, 47, 4638.
Scheme 4. Synthesis of Pd(II) complex 16. Reagents and conditions: (a)
[PdCl2(CH3CN)2], CH2Cl2, 80%.
4. (a) Boysen, M. M. K. Chem. Eur J. 2007, 13, 8648; (b) Castillon, S.; Claver, C.; Diaz,
Y. Chem Soc. Rev. 2005, 34, 702; (c) Dieguez, M.; Pamiés, O. P.; Claver, C. Chem.
Rev. 2004, 104, 3189; (d) Wang, Y. D.; Wang, F.; Miao, Z. W.; Chen, R. Y. Prog.
Chem. 2008, 20, 1923.
The structure of the complex 16 was determined by NMR anal-
ysis, as we could not get adequate crystal for X-ray analysis. The
most significant characteristics of the Pd(II) complex are the down-
field chemical shifts of the anomeric proton (from 5.7 ppm to
6.9 ppm), and the H-2 proton (from 3.8 ppm to 5.5 ppm). Beside
the downfield chemical shift (from 8.6 pp to 9.2 ppm), the imine
proton appears as a singlet in the complex instead of a doublet
as in the free ligand. These data are indicative of a Pd-coordination
through the nitrogen atom of the imine. On the other hand the
31PNMR analysis of the complex shows that the phosphorus atom
registers a 46 ppm downfield chemical shift, and appears at
35 ppm instead of ꢀ11 ppm as in the free ligands (see Supplemen-
tary data). All these data indicate that ligand 8 acts as a mixed P,N
ligand and coordinates the palladium through an enantioselective
chelate (similar to pathway C).
In conclusion, 4,6-benzylidene-2-deoxy-2-amino-b-glucopyr-
anosyl azide 1, with three orthogonal functional groups is an inter-
esting scaffold for the synthesis of chiral structurally diverse
ligands. Using click chemistry as key step of the approach, allows
the synthesis of triazol based ligands which are potential catalyst
precursors both in metal promoted and organic catalyses. The pre-
liminary results reported in this Letter illustrate the potential of
the approximation as a new P/N ligand for Pd(0) allylic alkylation
has been discovered. Other ligands, such as bifunctional organocat-
alyst with a phosphine and a thiourea moieties are easily obtained
from the developed method. These ligands are of interest as organ-
ocatalysts for processes such as the Morita–Baylis–Hillmann reac-
tion, Aza Baylis–Hillmann reaction, and intramolecular Ruhut–
Currier reaction. Work along these lines is actually under active
investigation in our group.
5. Laine, R. A. Pure Appl. Chem. 1997, 69, 1867.
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19. Data of compound 1: white solid. mp: 158–161 °C. ½a D20
ꢁ
ꢀ40.2 (c 1.0, CHCl3). 1
H
NMR (500 MHz, CDCl3): d = 7.55–7.50 (m, 2H), 7.45–7.35 (m, 3H), 5.56 (s, 1H),
4.52 (d, 1H, J = 8.8 Hz), 4.37 (dd, 1H, J = 10.5, 4.4 Hz), 3.79 (t, 1H, J = 10.0 Hz),
3.61–3.47 (m, 3H), 2.70 (t, 1H, J = 9.0 Hz), 2.25 (br, 2H, NH2). 13CNMR
(125 MHz): d = 136.9, 129.4, 128.4, 126.2, 110.3, 102.0, 92.1, 81.0, 73.1, 68.5,
68.4, 57.5. Anal. Calcd for C13H16N4O4: C, 53.42; H, 5.52; N, 19.17. Found: C,
53.42; H, 5.52; N, 19.05.
Acknowledgments
20. Data of compound 8: colorless oil. ½a D20
ꢁ
ꢀ32.7 (c 1.0, CHCl3). 1H NMR (500 MHz,
This work was supported by the Ministerio de Ciencia e Innova-
ción (Grant No. CTQ2010-21755-CO2-00), and the Junta de
Andalucía (P07-FQM-2774).
CDCl3): d = 8.58 (d, 1H, J = 3.8 Hz), 7.82–7.81 (m, 2H), 7.63–7.17 (m, 22H), 6.87–
6.84 (m, 1H), 5.64 (s, 1H), 5.60 (d, 1H, J = 8.5 Hz), 4.38 (m, 1H), 4.13–4.04 (m,
2H), 3.89–3.85 (m, 2H), 3.80–3.74 (m, 1H). 13C NMR (125 MHz, CDCl3):
d = 164.9, 164.8, 147.3, 138.7, 138.5, 138.4, 138.3, 137.7, 137.6, 136.9, 134.2
134.1, 133.7, 133.5, 130.6, 130.2, 129.3, 128.8, 128.7, 128.6, 128.5, 128.5, 128.4,
128.3, 126.3, 125.8, 119.7, 102.1, 87.2, 79.8, 72.4, 69.8, 68.3. 31P NMR
(121.4 MHz, CDCl3): d = 10.69. HMRS: calcd for C40H36N4O4P: 667.24770,
found: 667.24770.
Supplementary data
Supplementary data associated with this article can be found, in
21. Hayashi, T.; Yamamoto, A.; Hagihara, T.; Ito, Y. Tetrahedron Lett. 1986, 27, 191.