3348
S. Götze et al.
LETTER
(9) (a) Schmidt, R. R.; Michel, J. Angew. Chem., Int. Ed. Engl.
1980, 19, 731. (b) Kinzy, W.; Schmidt, R. R. Adv.
Carbohydr. Chem. Biochem. 1994, 50, 21.
(10) Vidadala, S. R.; Hotha, S. Chem. Commun. 2009, 2505.
(11) Mensah, E. A.; Azarelli, J. M.; Nguyen, H. M. J. Org. Chem.
2009, 74, 1650.
(12) Zhang, G.; Liu, Q.; Shi, L.; Wang, J. Tetrahedron 2008, 64,
339.
(13) Li, Y.; Tang, P.; Chen, Y.; Yu, B. J. Org. Chem. 2008, 73,
4323.
trichloroacetimidates gave glycosides with high diastereo-
selectivity and good yield. The reaction conditions are
convenient (r.t.) and particularly mild. Acid-sensitive
structures, for example the 5,6-isopropylidene group in
10a or the tert-butyl ester in 8d, remain unaffected as well
as groups, for example, the C=C double bonds in farnesyl
(6b) and cholesteryl (8a) glycosides, prone to reactions
with soft electrophiles, for example, required for thiogly-
coside or pentenyl glycoside activation. It is recommend-
ed to carry out the reactions under exclusion of oxygen.
Gold(I) catalyzes oxidations, for example, of benzyl alco-
hol. It is also advisable to conduct the reactions under dry
conditions, however, in the absence of molecular sieves in
order to prevent the formation of the corresponding
orthoester as the major product. Provided attention is paid
to these aspects, the gold(I)-catalyzed activation of glyco-
syl trichloroacetimidates appears useful for the glycosyla-
tion of sensitive glycosyl acceptors.
(14) Liebe, B.; Kunz, H. Helv. Chim. Acta 1997, 80, 1473.
(15) Schmidt, R. R. Angew. Chem., Int. Ed. Engl. 1986, 25, 212.
(16) Analytical Data for Compounds 6, 8, and 10
Compound 6a: [a]D25 –38.2 (c 1, CHCl3). 1H NMR (300
MHz, CDCl3): d = 4.52 (H-1, J1,2 = 7.7 Hz).18
Compound 6b: [a]D25 28.1. 1H NMR (300 MHz, CDCl3): d =
4.51 (H-1, J1,2 = 8.1 Hz).
Compound 8a: [a]D25 –5.1. 1H NMR (300 MHz, CDCl3): d =
4.51 (H-1, J1,2 = 8.1 Hz).19
Compound 8b: [a]D25 –28.0. 1H NMR (300 MHz, CDCl3):
d = 4.48 (H-1, J1,2 = 8.1 Hz).
Compound 8c: [a]D25 4.4. 1H NMR (300 MHz, CDCl3): d =
4.46 (H-1, J1,2 = 7.7 Hz).
References and Notes
Compound 8d: [a]D25 –6.8. 1H NMR (300 MHz, CDCl3): d =
4.47 (H-1, J1,2 = 8.1 Hz).20
(1) Spiro, R. G. Glycobiology 2002, 12, 43.
(2) (a) Dekker, J.; Rosen, J. W. A.; Büller, H. A.; Einerhand,
A. W. C. Trends Biochem. Sci. 2002, 27, 126. (b) Dwek,
R. A. Chem. Rev. 1996, 96, 683.
Compound 8e, b-anomer: [a]D25 11.3. 1H NMR (300 MHz,
CDCl3): d = 4.97 (H-1, J1,2 = 8.1 Hz).
Compound 8e, a-anomer: [a]D25 73.5. 1H NMR (300 MHz,
CDCl3): d = 5.56–5.49 (m, 2 H, H-1, H-2). 13C NMR (75.5
MHz, CDCl3): d = 95.1 (C-1).
(3) Dziadek, S.; Hobel, A.; Schmitt, E.; Kunz, H. Angew. Chem.
Int. Ed. 2005, 44, 7630.
(4) Kuhn, A.; Kunz, H. Angew. Chem. Int. Ed. 2007, 46, 454;
and literature cited therein.
(5) For reviews, see: (a) Zhu, X.; Schmidt, R. R. Angew. Chem.
Int. Ed. 2009, 48, 1900. (b) Codeé, D. C. J.; Litjens, R. E. J.
N.; van den Bos, L. J.; Overkleft, H. S.; van der Marel, G. A.
Chem. Soc. Rev. 2005, 34, 769. (c) Manabe, S.; Ito, Y. Curr.
Bioact. Compd. 2008, 4, 258.
(6) Morales-Serna, A.; Diaz, J.; Matheu, M. I.; Castillon, S. Eur.
J. Org. Chem. 2009, 23, 3849.
Compound 10a: [a]D25 25.6 (c 1, CHCl3). 1H NMR (300
MHz, CDCl3): d = 5.32 (H-1, J1,2 = 3.7 Hz).
Compound 10b: [a]D25 121.5 (c 1, CHCl3). 1H NMR (300
MHz, CDCl3): d = 4.93 (H-1, J1,2 = 3.7 Hz).
(17) Eichler, E.; Jennings, H. J.; Gilbert, M.; Whitfield, D. M.
Carbohydr. Res. 1999, 319, 1.
(18) Fischer, E.; Helferich, B. Liebigs Ann. Chem. 1911, 383, 68.
(19) (a) Iga, D. P.; Iga, S.; Schmidt, R. R.; Buzas, M.-C.
Carbohydr. Res. 2005, 340, 2052. (b) Kulkarni, S. S.;
Gervay-Hague, J. Org. Lett. 2008, 10, 4739.
(20) Pleuss, N.; Kunz, H. Synthesis 2005, 122.
(7) Caputo, R.; Kunz, H.; Mastroianni, D.; Palumbo, G.;
Petadella, S.; Solla, F. Eur. J. Org. Chem. 1999, 3147.
(8) Mensah, E. A.; Nguyen, H. M. J. Am. Chem. Soc. 2009, 131,
8778.
Synlett 2009, No. 20, 3346–3348 © Thieme Stuttgart · New York