I. Maya et al. / Tetrahedron Letters 42 (2001) 5413–5416
5415
In conclusion, a rapid and practical two-step one-pot
procedure for the synthesis of O-unprotected N-
glycopyranosyl, N%-substituted thioureas from 1,2-trans
arranged glycopyranosyl amines has been developed.
This represents a better alternative to the currently used
O/N protection–deprotection steps in the synthesis of
glycosyl thioureas and thiourea-tethered pseudooligo-
saccarides30 and bolaamphiphiles.31
However, these compounds were later shown to
undergo fast decomposition under physiological
conditions20 and no further chemistry has been
described. b- -Glucopyranosyl isothiocyanate (3) was
D
prepared in low yield (22%) and this compound was
spectroscopically characterised only by an IR absorp-
tion, and no reactions of the NCS group were
described.17
We have investigated various approaches for the syn-
Acknowledgements
thesis of 3 and obtained the most convenient results by
reacting b-
-glucopyranosyl amine21 (1) with thiophos-
D
gene (Scheme 1) in a buffered medium (NaHCO3/CO2,
pH 8). After standard workup and purification proce-
dure, a mixture of 3 and the corresponding 1,2-cyclic
thiocarbamate 5 was obtained (64%);22 the 3:5 ratio
We thank the Direccio´n General de Investigacio´n Cien-
t´ıfica y Te´cnica (Grant no PB 97/0730) and the Junta de
Andalucia (FQM134) for financial support. O.L.
thanks the Ministerio de Educacio´n y Cultura for a
fellowship. This work is part of the European Pro-
gramme COST D13/0001/98.
1
measured by integration of H NMR signals was 1:5 in
(CD3)2SO and 3:2 in D2O, showing that 3 and 5 are in
a solvent dependent equilibrium. This mixture could be
transformed into thioureas (Table 1) by adding alkyl or
aryl amines 7a–c, diethylamine 7d,23 the aminoacids
glycine or taurine 7e,f, or O-unprotected glycosyl-
amines 7g,h to the same flask where 3/5 were formed.
Similarly, bolaamphiphiles24 8i and 8j were prepared
using a,v-polymethylenediamines 7i and 7j.
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1
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.