Chemo-Enzymatic Synthesis of Amino Acids in Water
FULL PAPERS
(
40 mL) was added and the resulting suspension stirred for 3 h. Acknowledgements
The solid was collected by filtration and washed thoroughly
with portions of 30 mL 2-propanol until the washings were col-
ourless (approx. 5 times). Finally, the catalyst was dried at 558C
under vacuum for 2 h. Rh loading was determined by INAA:
C. S. gratefully acknowledges the Dutch National Research
School Combination Catalysis (NRSC-Catalysis) for financial
support. U. H. thanks the Royal Netherlands Academy of Arts
and Sciences (KNAW) for a fellowship. Adriaan J. Minnaard
is gratefully acknowledged for fruitful discussions.
1
1 mg Rh/g support, which corresponds to an Altetrahedral/Rh ra-
tio of approximately 10.
References
Hydrogenation Reaction of Cascade
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All hydrogenation experiments were performed with 0.1 g of
immobilized catalyst (~1 wt % Rh). 1-AlTUD-1 (0.1 g) was
transferred to the autoclave under a nitrogen atmosphere, fol-
lowed by substrate solution (50 mL water, 0.05 M 2). The
sealed autoclave was purged with hydrogen by pressurising
to 7 bars while stirring at 300 rpm, followed by release of pres-
sure. This cycle was repeated 5 times and finally the desired
pressure was applied and the stirring speed was increased to
[
[
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1
000 rpm. After 1 h the remaining hydrogen pressure was re-
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1
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(
50 mL), phosphate buffer (5 mL, pH 7.5, 1.1 M) was added
followed by AM (205 mg, 175 U) or PK (90 mg, 700 U). This
mixture was shaken for 24 h during which samples were ob-
tained. The samples were adjusted to pH 5 with 1 M HCl, heat-
ed to 608C with Norit, filtered over Celite and lyophilised.
1
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þ
DOWEX-50 (H ) column, which was rinsed with water until
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again lyophilised.
[
[
[
[
[
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One-Pot Procedure
1
-AlTUD-1 (0.1 g) and acylase I from Aspergillus melleus
(
82 mg) were transferred to the autoclave under a nitrogen at-
mosphere, followed by substrate solution [50 mL, 0.05 M in
phosphate buffer (pH 7.5, 0.1 M) for the one-pot or in water
for the modified one-pot protocol, respectively]. The sealed
autoclave was purged with hydrogen by pressurising to 7 bars
while stirring at 300 rpm, followed by release of pressure.
This cycle was repeated 5 times and finally the desired pressure
was applied and the stirring speed was increased to 1000 rpm.
After 24 h the remaining hydrogen pressure was released and
the autoclave was purged three times with nitrogen.
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1
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Adv. Synth. Catal. 2006, 348, 471 – 475
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