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groups by hydrogenation, was removed under reduced pressure. A
chemical purity of at least 95%, as determined by HPLC, was routinely
achieved for the final product 2 (Figure 1). Mass yield and radioactivity
recoveries were 90 and 93%, respectively. As unlabeled glucose was
added at the outset of the synthesis as a diluent, the specific radioactivity
of the final product was 1:19 mCi=mmol, starting with 1 mCi of d-
½U-14Cꢀglucopyranose (specific activity 4:68 mCi=mmol).
The overall mass yield and radioactivity recovery were 54 and 51%,
respectively, providing a direct convenient route to the radiolabeled
hydrolyzable tannin 2.
Experimental
½U-14Cꢀ-d-Glucopyranose in an ethanol=H2O solution ð0:1 mCi=ml;
4:68 mCi=mmolÞ was purchased from Perkin-Elmer Life Science, Inc.
(Boston, MA). All other reagents (ACS reagent grade) were purchased
from Aldrich (St. Louis, MO). Before use, 1,2-dichloroethane was
distilled. All other chemicals were used without further purification.
Radioactivity was quantified with a Wallac 1409 liquid scintillation
analyzer (Turku, Finland). UV spectra were taken in acetonitrile
solution with an Agilent 8453 UV-visible spectrometer (Agilent
Technologies, Palo Alto, CA). The Chromatotron (Harrison Research,
CA Model 8924) was equipped with a pump (Model RHSY, Fluid
Metering Inc., NY). A Hewlett-Packard 1050 HPLC system with two
pumps, an autosampler and UV-detector was equipped with a C-18
(
column (Adsorbosphere XL C18 90 A, 3 mm, 100 ꢁ 4:6 mm, Alltech,
Deerfield, IL). Mobile phase A was water containing 0.1% acetic acid
(v/v) and mobile phase B was acetonitrile containing 0.1% acetic acid
(v/v). The flow rate was 1 ml=min. The UV detector was set at 220 nm.
The gradient started at 5% B, increased to 100% B in 3 min, then
returned to 5% B in 3 min, and the column was re-equilibrated for
7 min.
The reaction conditions were optimized using unlabeled reagents.
Identities and purities of natural abundance intermediates and products
1
1
were determined by H and 13Cf Hg NMR spectroscopy (Bruker 200
MHz Avance spectrometer), electrospray mass spectrometry (Campus
Chemical Instrumentation Laboratory, Department of Chemistry, The
Ohio State University), and UV}visible spectra (Figure 2), and were
in agreement with previously reported data.9 The identities of the
Copyright # 2002 John Wiley & Sons, Ltd.
J Label Compd Radiopharm 2003; 46: 99–105