Anomeric Effect of the Nitrogen Atom in the Isocyano and Urea Groups
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X. Li, S. J. Danishefsky, J. Am. Chem. Soc. 2008, 130, 5446–
an argon atmosphere was added iodine (2.0 mg, 0.0070 mmol). Af-
ter stirring at room temperature for 15 min, pyrrolidine (0.026 mL,
0.32 mmol) was added. The resulting reaction mixture was stirred
at room temperature for 30 min and then filtered. The filtrate was
poured into saturated aqueous NaHSO3 solution, and the aqueous
layer was extracted with Et2O. The combined organic layers were
washed with brine, dried (Na2SO4), and then concentrated under
reduced pressure. The resulting residue was purified by silica gel
5448.
[8]
a) C. V. Holland, D. Horton, J. S. Jewell, J. Org. Chem. 1967,
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1
Signal assignments were made based on the results of 2D H–
chromatography (AcOEt/hexane, 3:1) to afford β-urea 11 (31 mg,
1H COSY analysis. See the Supporting Information.
79%) as a white gum. [α]2D1 = –7.4 (c = 1.00, CHCl ). IR (KBr): ν
˜
3
[12]
[13]
= 3389, 2955, 2876, 1746 cm–1. H NMR (400 MHz, CDCl3): δ =
1
E. L. Eliel, S. H. Wilen, L. N. Mander in Stereochemistry of
Organic Compounds, Wiley, 1994, pp. 690–700.
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1.90 (br. s, 4 H, -NCH2-CH2-), 2.04 (s, 3 H, OAc), 2.05 (s, 3 H,
OAc), 2.06 (s, 3 H, OAc), 3.32 (br. s, 4 H, -NCH2-), 3.46 (dd, J =
11.7, 10.7 Hz, 1 H, 5Ј-H), 4.06 (dd, J = 11.7, 5.6 Hz, 1 H, 5-H),
4.88 (t, J = 9.5 Hz, 1 H, 2-H), 4.99 (ddd, J = 10.7, 9.5, 5.6 Hz, 1
H, 4-H), 5.10 (dd, J = 9.5, 9.3 Hz, 1 H, 1-H), 5.32 (d, J = 9.3 Hz,
1 H, NH), 5.33 (t, J = 9.5 Hz, 1 H, 3-H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 20.63, 20.66, 20.83, 25.35, 45.40, 64.07,
69.31, 70.87, 72.32, 80.78, 154.78, 169.79, 169.90, 171.50 ppm.
C16H24N2O8 (372.15): calcd. C 51.61, H 6.50, N 7.52; found C
51.37, H 6.49, N 7.26.
[14]
[15]
A similar phenomenon was observed in the case of 2,3,4-tri-
1
O-acetyl-β--xylopyranosyl chloride 2, which exists in the C4
conformation preferentially in chloroform solution, but adopts
the 4C1 conformation in the solid state. Moreover, X-ray analy-
sis showed that the C1–O6 bond is not shortened and the C1–
chlorine bond is not lengthened. See: a) G. Kothe, P. Luger, H.
Paulsen, Carbohydr. Res. 1974, 37, 283–292; b) H. Paulsen, P.
Luger, F. R. Heiker in Anomeric Effect: Origin and Conse-
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Horton), American Chemical Society, Washington, DC, 1979,
pp. 63–79.
CCDC-756982 (for 7) and -7569783 (for 8) contain the supplemen-
tary crystallographic data for this paper. These data can be ob-
tained free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
Supporting Information (see footnote on the first page of this arti-
cle): Spectral data for all relevant compounds, 2D 1H–1H COSY,
spin decoupling experiments, and spin simulation.
[16]
A similar tendency in the valence bond angles was reported by
Jeffery and Lemieux, who evaluated the crystallographic data
of O-glycosides. See: a) G. A. Jeffrey in Anomeric Effect: Origin
and Consequences, ACS Symposium Series 87 (Eds.: W. A. Sza-
rek, D. Horton), American Chemical Society, Washington, DC,
1979, pp. 50–62; b) R. U. Lemieux, S. Koto, D. Voisin in Anom-
eric Effect: Origin and Consequences, ACS Symposium Series
87 (Eds.; W. A. Szarek, D. Horton), American Chemical Soci-
ety, Washington, DC, 1979, pp. 17–29.
Acknowledgments
Financial support from the Sumitomo Foundation and the Kochi
University President’s Discretionary Grant is greatly appreciated.
Taihei Nishiyama and Professor Minoru Isobe (Nagoya University)
are acknowledged for their contributions to the early stage of this
work.
[17]
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M. Benn, A. S. Jones, J. Chem. Soc. 1960, 3837–3841.
Exchangeable protons on the nitrogen atoms in ureas appear
1
at variable chemical shifts in CDCl3 and interfere with the H
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NMR spectroscopic analysis. Accordingly, we employed a sec-
ondary amine (pyrrolidine) as a component of the xylopyr-
anosyl ureas, which minimizes the urea protons.
For details on the assignment of the signals and spin decoup-
ling experiments, see the Supporting Information.
F. A. Bovey, L. Jelinski, P. A. Mirau in Nuclear Magnetic Reso-
nance Spectroscopy, Academic Press, 1988.
For spin simulation, we employed the program “Let’s Spin,
Version 2.01” produced by Osamu Yamamoto. For details, see
the Supporting Information.
P. L. Durette, D. Horton, J. Org. Chem. 1971, 36, 2658–2669.
R. U. Lemieux, R. M. Ratclifee, Can. J. Chem. 1979, 57, 1244–
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C. L. Perrin, Tetrahedron 1995, 51, 11901–11935.
Received: July 5, 2010
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Published Online: October 4, 2010
Eur. J. Org. Chem. 2010, 6331–6337
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
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