Asymmetric synthesis of L-[4-13C]lysine by alkylation of oxazinone derivative as a chiral glycine equivalent

Article abstract of DOI:10.1002/jlcr.868

L-[4-¹³C]Lysine (2) was synthesized from sodium [2- ¹³C]acetate (3) and Dellaria's oxazinone 1 as a chiral glycine equivalent. Wittig reaction of the glycinal 7 and ¹³C-labeled phosphonium ylide 5, prepared from sodium [2-¹³C]acetate (3), gave the α, β-unsaturated ester 8. The ester 8 was converted to the allylic bromide 10. Alkylation of the oxazinone 1 with 10 proceeded with high diastereoselectivity. Ethanolysis, hydrogenation of the double bond with diimide, removal of the chiral auxiliary, and hydrolysis gave L-[4- ¹³C]lysine (2). Copyright

Full text of DOI:10.1002/jlcr.868

JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS
J Label Compd Radiopharm 2004; 47: 787–795.
Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jlcr.868
Research Article
Asymmetric synthesis of l-[4-13C]lysine by alkylation
of oxazinone derivative as a chiral glycine equivalent
Kazuhiko Takatori, Akira Hayashi and Masahiro Kajiwara*
Department of Medicinal Chemistry, Meiji Pharmaceutical University, 2-522-1 Noshio,
Kiyose-shi, Tokyo 204-8588, Japan
Summary
l-[4-13C]Lysine (2) was synthesized from sodium [2-13C]acetate (3) and Dellaria’s
oxazinone 1 as a chiral glycine equivalent. Wittig reaction of the glycinal 7 and
13C-labeled phosphonium ylide 5, prepared from sodium [2-13C]acetate (3), gave the
a, b-unsaturated ester 8. The ester 8 was converted to the allylic bromide 10.
Alkylation of the oxazinone 1 with 10 proceeded with high diastereoselectivity.
Ethanolysis, hydrogenation of the double bond with diimide, removal of the chiral
auxiliary, and hydrolysis gave l-[4-13C]lysine (2). Copyright # 2004 John Wiley &
Sons, Ltd.
Key Words: l-[4-13C]lysine; labeled amino acid; chiral glycine equivalent; oxazinone
Introduction
Amino acids are the fundamental constituents of proteins and the biosynthetic
starting materials of a large number of biologically important primary and
secondary metabolites. The use of stable isotope-labeled amino acids has
became important for the diagnosis of disease, the study of the biosynthesis
of natural products and other biological studies.1–3 We have reported asymme-
tric syntheses of l-[3-13C]phenylalanine, l-[3-13C]tyrosine,4 l-[2-13C]aspartic
acid5 and l-[3-13C]alanine6 from Dellaria’s oxazinone 17 or its 13C-labeled
form as a chiral optically active glycine equivalent. This method is also
applicable to the synthesis of various amino acids with specific labeling at
other positions. In this paper, we describe an asymmetric synthesis of l-
[4-13C]lysine (2).8–14
*Correspondence to: M. Kajiwara, Department of Medicinal Chemistry, Meiji Pharmaceutical University,
2-522-1 Noshio, Kiyose-shi, Tokyo 204-8588, Japan. E-mail: kajiwara@my-pharm.ac.jp
Contract/grant sponsor: Ministry of Education, Culture, Sports and Technology of Japan
Copyright # 2004 John Wiley & Sons, Ltd.
Received 14 June 2004
Accepted 29 June 2004

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K. TAKATORI ET AL.
In our synthetic plan, the carbons of lysine originate from two molecules of
sodium acetate and one molecule of glycine, both of which are commercially
available as 13C-labeled compounds, suitable for the synthesis of multiply and
specifically labeled lysine.
Results and discussion
The C3-C6 unit of lysine was prepared from sodium [2-13C]acetate (3) and
glycine (4) (Scheme 1). Phosphonium ylide 5 was derived from sodium
[2-13C]acetate (3) via ethyl bromo[2-13C]acetate5,15 by a usual method in 71%
yield from 3.16,17 Benzylation of glycine with 3 eq. of benzyl bromide afforded
N,N-dibenzylglycine benzyl ester (6) in 96% yield. Conversion to the aldehyde
7 was performed sequentially by LiAlH4 reduction to 2-(dibenzylamino)etha-
nol and Swern oxidation of the hydroxyl group, in 85% yield.18 The aldehyde
7 was immediately used in the next step without purification. Wittig reaction
of the 13C-labeled phosphonium ylide 5 and 7 gave the a,b-unsaturated ester 8
in 94% yield from 5. DIBAL reduction of the ester 8 and substitution of the
resulting alcohol 9 with LiBr, methanesulfonyl chloride and triethylamine gave
the 13C-labeled allylic bromide 10 in 62% yield from 8.
Alkylation of Dellaria’s oxazinone 1 (corresponding to the C1-C2 unit of
lysine), which could be prepared in 13C-labeled form, if required, by modifying
our reported method from sodium acetate,5 with the 13C-labeled allylic
bromide 10 was performed by treatment of 1 with lithium bis(trimethylsilyl)
amide (LHMDS) in THF:DME=5:1, followed by addition of HMPA and 10
to the resulting enolate of 1 at À408C to give the allylic oxazinone 11 with high
diastereoselectivity, syn:anti=1:16 (Scheme 2). The ratio was enhanced to
99% de., as determined by HPLC analysis, by crystallization from ethyl
acetate–hexane in 86% yield based on 10. Ethanolysis of the oxazinone ring
and removal of the Boc group of 11 were simultaneously carried out by
Scheme 1. Reagents and conditions: (a) BnCl (3 eq), K2CO3, (1.7 eq.), 96%; (b)
(i) LiAlH4, 85%, (ii) DMSO, (COCl)2, Et3N, quant.; (c) (i) PhCOBr, PhCO2H,
(ii) Br2, (iii) EtOH, (iv) Ph3P, (v) NaOH, 71% from 3; (d) benzene, 94% from 5;
(e) DIBAL, 87%; (f) LiBr, MsCl, Et3N, 71%
Copyright # 2004 John Wiley & Sons, Ltd.
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ASYMMETRIC SYNTHESIS OF L-[4-13C]LYSINE
789
Scheme 2. Reagents and conditions: (a) LHMDS, then 10 HMPA, À408C, 86%
based on 10; (b) sat. HCl/EtOH, 93%; (c) KO2CN=NCO2K, AcOH, twice, 13
of 70% and 14 of 30%; (d) sat. HCl/EtOH, 73%; (e) (i) H2, Pd(OH)2, (ii) 6 M
HCl, 51% from 13
heating at 608C in ethanol-saturated HCl gas to give 12 in 93% yield.
Hydrogenolysis of the three benzyl groups, including the a-N-alkyl chain of
12, and hydrogenation of the double bond proceeded simultaneously on
various catalysts, such as Pd–C, Pd(OH)2, PtO2, and Wilkinson’s catalyst, but
under all conditions, the unexpected product, ethyl 2-amino[4-13C]hexanote
was mainly obtained. Therefore, the double bond alone was hydrogenated
initially. Hydrogenation of 12 by treatment with diimide afforded the desired
13,19 but the reaction was partial and the starting material 12 was also
recovered (12:13=ca. 1:2). The crude mixture of 12 and 13 was hydrogenated
once again with diimide. The reaction went to completion, affording 13 and its
hydrazide 14, which was formed from the ester 13 and hydrazine generated
from diimide, in 70 and 30% yields, respectively. The hydrazide 14 was readily
converted to the ethyl ester 13 with saturated (sat.) HCl in ethanol at 608C
for 6 h in 73% yield. Hydrogenolysis of the three benzyl groups with
Pd(OH)2 proceeded cleanly at 608C in ethanol to give lysine ethyl ester.
Finally, hydrolysis of lysine ethyl ester gave l-[4-13C]lysine (2) in 51% yield
from 13.
The 13C-NMR spectrum of 2 showed the enriched signal at 24.2 ppm,
assigned to the 4-position of lysine. The optical purity was 92% ee and the
absolute configuration was l, as determined by HPLC analysis using a chiral
column.20
In summary, we have synthesized l-lysine (2) 13C-labeled at the 4-position,
which is the most difficult position in lysine to label specifically, from sodium
[2-13C]acetate (3) by using diastereoselective alkylation of Dellaria’s oxazinone
1. Other specifically labeled 13C-isotopomers should be similarly obtainable
from the appropriate commercially available sodium 13C-acetate and
13C-glycine.
Copyright # 2004 John Wiley & Sons, Ltd.
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K. TAKATORI ET AL.
Experimental
Sodium [2-13C]acetate (99 at% 13C) was supplied by Cambridge Isotope
Laboratories. Melting points were measured on a Yanaco micro melting
point apparatus and are uncorrected. 1H- and 13C-NMR spectra were
recorded on
a
Varian Gemini-2000 (300 MHz) Fourier-transform
spectrometer. The chemical shifts are reported in d values relative to
tetramethylsilane (TMS) at 0 ppm in CDCl3 or sodium 3-trimethylpropio-
nate-d4 (TSP) at 0 ppm in D2O for 1H-NMR and relative to CDCl3
at 77.0 ppm or TSP at 0 ppm in D2O for 13C-NMR. IR spectra were
recorded on a JASCO VALOR-III Fourier-transform spectrometer. EI- and
HR-FAB-MS were obtained with a JEOL JMS-700 double-focusing
spectrometer. HPLC analysis was carried out on a JASCO 800 Series HPLC
system with a JASCO 875-UV detector. HPLC-CD analysis for determination
of the optical purity of lysine was performed at 228C by using a Crown
Pak CR(-) column (150 mm  4 mm i.d.), purchased from Daicel, and
pH 1.0 HClO4 as the eluent. Other conditions were as described in a previous
report.20
Ethyl 2-(triphenylphosphoranylidene)[2-13C]acetate (5)
Bromo[2-13C]acetyl bromide was prepared from sodium [2-13C]acetate
(3, 4.82 g) by using the method previously reported.5,15 To the crude bromo-
[2-13C]acetyl bromide was added slowly dropwise dry ethanol (7.0 ml,
121.0 mmol), and the mixture was stirred overnight at room temperature
(rt). The mixture was extracted three times with benzene (total 66 ml),
then the combined organic layers were washed with sat. NaCl, dried over
MgSO4, and filtered. Triphenylphosphine (15.9 g, 61.0 mmol) was added
to the solution. The mixture was stirred overnight at rt. The resulting
precipitate was collected by filtration, and washed with benzene. The
precipitate was dissolved in water (54 ml), and benzene (30 ml) was
added. Then 3 M NaOH (8.3 ml, 24.9 mmol) was slowly added dropwise to
the mixture at rt with vigorous stirring. The organic layer was separated,
and the aqueous layer was extracted three times with benzene. The com-
bined organic layers were washed with sat. NaCl, dried over MgSO4, and
evaporated. The crude product was crystallized from CHCl3-ether to
give 5 (14.5 g) in 71% yield. mp. 124.9–126.38C. 1H-NMR (CDCl3) d:
0.88–1.35 (br, 3H), 2.45–3.44 (br-d, JC-H=148 Hz, 1H), 3.97 (br, 2H),
7.51–7.69 (m, 15H). 13C-NMR (CDCl3) d: 30.2 (d, JC-P=126.0 Hz). IR
(KBr) cmÀ1: 3057, 2977, 2901, 1605, 1483, 1437, 1368, 1323, 1300, 1121, 1106,
1060, 879, 755, 696, 520, 507. HR-MS Calcd for C21 13CH21O2P: m/z
349.1313. Found: m/z 349.1305 (M+). EI-MS m/z (%): 349 (M+, 19), 302
(100), 277 (21).
Copyright # 2004 John Wiley & Sons, Ltd.
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ASYMMETRIC SYNTHESIS OF L-[4-13C]LYSINE
791
Ethyl (E)-4-dibenzylamino-2-[2-13C]butenoate (8)
Benzylation of glycine (4, 5.00 g, 66.6 mmol) with 3.0 eq. of benzyl bromide
and 1.7 eq. of K2CO3 in water at 1008C for 15 h gave the ester 6 (22.18 g) in
96% yield. Reduction of the ester 6 (22.2 g, 64.2 mmol) with LiAlH4 in THF at
rt for 3 h gave 2-(dibenzylamino)ethanol (13.2 g) in 85% yield. Swern
oxidation of this alcohol (5.03 g, 20.8 mmol) with 7 eq. of DMSO, 5 eq. of
oxalyl chloride and 12 eq. of triethylamine gave 7.12 g of crude N,N-
dibenzylglycinal (7).18
To a solution of the resulting 7 (corresponding to 20.8 mmol) in benzene
(70 ml) was added 13C-labeled phosphonium ylide 5 (6.55 g, 17.8 mmol). The
1
3
mixture was stirred for 13 h at rt, then evaporated to volume. A mixture of
hexane and ether (4:1, 300 ml) was added. The precipitated phosphine oxide
was filtered off, and the filtrate was evaporated. The crude product was
purified by column chromatography on silica gel (hexane:ethyl acetate=7:1)
to give 8 (5.45 g) in 94% yield from 5. 1H-NMR (CDCl3) d: 1.29 (t, J=7.1 Hz,
3
3H), 3.19 (dt, J=1.6, 5.8 Hz, JC-H=5.8 Hz, 2H), 3.59 (s, 4H), 4.19 (q,
J=7.1 Hz, 2H), 6.08 (ddt, JC-H=162.6 Hz, J=15.7, 16 Hz, 1H), 7.00 (ddt,
2JC-H=2.2 Hz, J=15.7, 5.8 Hz, 1H), 7.20–7.40 (m, 10H). 13C-NMR (CDCl3)
d: 122.7. IR (neat) cmÀ1: 3029, 2981, 2931, 2799, 1718, 1495, 1368, 1304, 1264,
1178, 1029, 747, 699. HR-MS Calcd for C19 13CH23NO2: m/z 310.1762.
Found: m/z 310.1763 (M+). EI-MS m/z (%): 310 (M+, 6), 281 (8), 265 (6), 233
(12), 219 (92), 210 (10), 91 (100).
(E)-4-Dibenzylamino-2-[2-13C]buten-1-ol (9)
To a stirred solution of the ester 8 (4.80 g, 15.5 mmol) in dry CH2Cl2 (40 ml)
was added dropwise a 1 M solution of DIBAL in toluene (43.4 ml, 43.4 mmol)
over 1 h at À788C, and the mixture was stirred for 2 h. The reaction was
quenched with MeOH, and a large amount of ether and a proper amount of
sat. NaCl were added to precipitate aluminous salt. The precipitate was filtered
off, and the filtrate was evaporated. The crude product was chromatographed
1
on silica gel to give the alcohol 9 (3.53 g) in 87% yield. H-NMR (CDCl3) d:
3
3.07 (t, JC-H=5.8 Hz, J=5.8 Hz, 2H), 3.58 (s, 4H), 4.10 (m, 2H), 5.77 (m,
1H), 5.79 (ddt, JC-H=154.4 Hz, J=15.4, 5.8 Hz, 1H), 7.20–7.39 (m, 10H). 13C-
NMR (CDCl3) d: 131.7. IR (neat) cmÀ1: 3342, 3027, 2796, 1494, 1454, 1366,
1124, 1074, 1028, 971, 746, 698. HR-MS Calcd for C17 13CH21NO: m/z
268.1657. Found: m/z: 268.1665 (M+). EI-MS m/z (%): 268 (M+, 9), 210 (20),
197 (25), 191 (19), 106 (34), 91 (100).
(E)-Dibenzyl(4-bromo-2-[3-13C]butenyl)amine (10)
A mixture of alcohol 9 (3.53 g, 13.2 mmol) and LiBr (17.2 g, 198.3 mmol) was
dissolved in dry THF (73 ml) at 08C, and triethylamine (9.2 ml, 66.1 mmol) was
Copyright # 2004 John Wiley & Sons, Ltd.
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K. TAKATORI ET AL.
added. Methanesulfonyl chloride was added dropwise to the mixture at
À788C, and the whole was slowly warmed to À408C over 2 h. The mixture was
stirred for 1 h at that temperature, and then allowed to warm to 08C. The
mixture was poured into sat. NaHCO3, and extracted five times with ether.
The combined organic layers were washed with sat. NaCl, dried over MgSO4,
and evaporated at 08C. The residue was rapidly chromatographed on silica gel
1
(hexane:ether =10:1) to give the bromide 10 (3.12 g) in 71% yield. H-NMR
3
(CDCl3,) d: 3.07 (t, JC-H=6.0 Hz, J=6.0 Hz, 2H), 3.57 (s, 4H), 3.95 (ddd,
2JC-H=4.1 Hz, J=7.7, 0.5 Hz, 2H), 5.85 (m, 1H), 5.86 (ddt, JC-H=160.2 Hz,
J=15.1, 7.4 Hz, 1H), 7.20–7.39 (m, 10H). 13C-NMR (CDCl3) d: 129.0.
(E)-(3S,5S)-2,3,5,6-Tetrahydro-3-(4-dibenzylamino-[2-13C]butenyl)-5-phe-
nyl-N-(tert-butyloxycarbonyl)-4H-1,4-oxazin-2-one (11)
LHMDS was prepared from BuLi (1.58 M in hexane solution, 8.6 ml,
13.6 mmol) and 1,1,1,3,3,3-hexamethyldisilazane (3.1 ml, 14.7 mmol) in a
mixture of THF (8 ml) and DME (4 ml) at 08C under nitrogen. To a solu-
tion of oxazinone 1 (3.13 g, 11.3 mmol) in a mixture of THF (10 ml) and
DME (5 ml) was added dropwise the LHMDS solution though a cannula at
À408C under nitrogen. The flask was washed with THF (6 ml), and the solu-
tion was similarly added to the LHMDS solution. The mixture was stirred
for 30 min, then HMPA (2.62 ml, 15.1 mmol) was added. This mixture was
stirred for 10 min, then a solution of the bromide 10 (3.12 g, 8.44 mmol) in
THF (16 ml) and DME (3 ml) was added dropwise over 20 min. The reaction
mixture was stirred at À408C overnight. The reaction was quenched with sat.
NH4Cl, and the mixture was extracted five times with ether. The combined
organic layers were washed with sat. NaCl, dried over MgSO4, and
evaporated. The residue was chromatographed on silica gel (hexane:ethyl
acetate=4:1). Pure 11 (4.28 g, 86% yield) was obtained by crystallization from
1
hexane–ethyl acetate. mp. 142.4–143.38C. H-NMR (CDCl3, 558C) d: 1.26
(brs, 9H), 2.74 (m, 2H), 3.06 (t, J=5.8 Hz, 2H), 3.58 (s, 4H), 4.31 (m, 1H), 4.71
(dd, J=11.5, 3.0 Hz, 1H), 4.71–5.10 (m, 2H), 5.68 (m, JC-H=154.4 Hz, 1H),
5.70 (m, 1H), 7.06 (m, 2H), 7.18–7.37 (m, 13H). 13C-NMR (CDCl3, 558C) d:
126.6. IR (KBr) cmÀ1: 2977, 2923, 2797, 1740, 1699, 1453, 1359, 1297, 1221,
1169, 1123, 1075, 746, 698. HR-MS Calcd for C32 13CH38N2O4: m/z 527.2865.
Found: m/z 527.2874 (M+). EI-MS m/z (%): 527 (M+, 31), 470 (10), 336 (16),
251 (49), 237 (13), 210 (14), 196 (44), 106 (25), 91 (100). [a]2D0=+114.08
(c. 1.01, CHCl3).
Ethyl (2S)-6-dibenzylamino-2-[(S)-2-hydroxy-1-phenylethylamino)]-4-[4-13C]
hexenoate (12)
A solution of the oxazinone 11 (2.02 g, 3.83 mmol) in sat. HCl in ethanol
(40 ml) was stirred at 608C for 6 h. The mixture was evaporated, and the
Copyright # 2004 John Wiley & Sons, Ltd.
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ASYMMETRIC SYNTHESIS OF L-[4-13C]LYSINE
793
residue was made basic with sat. NaHCO3. The mixture was extracted four
times with ethyl acetate, and the combined organic layers were washed
with sat. NaCl, dried over Na2SO4, and evaporated. The residue was chro-
1
matographed on silica gel to give 12 (1.68 g) in 93% yield. H-NMR (CDCl3)
2
d: 1.08 (t, J=7.1 Hz, 3H), 2.41 (q, JC-H=6.3 Hz, J=6.3 Hz, 2H), 3.00 (t,
3
3JC-H=6.0 Hz, J=6.0 Hz, 2H), 3.31 (dt, JC-H=4.7 Hz, J=6.0 Hz, 1H),
3.53 (dd, J=11.0, 8.2 Hz, 1H), 3.54 (s, 4H), 3.65 (dd, J=11.0, 4.7 Hz, 1H),
3.75 (dd, J=8.2, 4.7 Hz, 1H), 3.87 (q, J=7.1 Hz, 2H), 4.31 (m, 1H), 5.57
(m, JC-H=152.7 Hz, 1H), 5.63 (m, 1H), 7.19–7.39 (m, 15H). 13C-NMR
(CDCl3) d: 128.0. IR (neat) cmÀ1: 3440, 3332, 3028, 2925, 2796, 1734,
1494, 1454, 1371, 1196, 1028, 972, 748, 699. HR-MS Calcd for C29
13CH36N2O3: m/z 473.2759. Found: m/z 473.2766 (M+). EI-MS m/z (%):
473 (M+, 0.2), 442 (24), 382 (23), 336 (18), 278 (16), 251 (17), 222 (21),
203 (33), 196 (40), 121 (18), 106 (29), 91 (100). [a]2D0=+31.38 (c. 1.03,
CHCl3).
Ethyl (2S)-6-dibenzylamino-2-[(S)-2-hydroxy-1-phenylethylamino)]-4-[4-13C]
hexanoate (13)
To a mechanically stirred mixture of 12 (1.68 g, 3.54 mmol) and dipotassium
azodicarboxylate (48.8 g, 248 mmol) in dry acetonitrile (350 ml) was added
dropwise acetic acid (28.3 ml, 495 mmol) at 708C over 8 h, and the mixture was
stirred for an additional 3 h. The mixture was made basic with sat. NaHCO3,
and filtered through Celite, then the filtrate was evaporated. Sat. NaHCO3 was
added to the residue, and the mixture was extracted five times with ethyl
acetate. The combined organic layers were washed with sat. NaCl, dried over
MgSO4, and evaporated. The crude product was treated once again under
these conditions for diimide reduction. The resulting products were separated
by chromatography on silica gel (hexane:ethyl acetate=1:1) to give 13 (1.17 g)
1
and 14 (548 mg) in 70 and 30% yields, respectively. 13: H-NMR (CDCl3) d:
1.09 (t, J=7.1 Hz, 3H), 1.05–1.60 (m, 6H), 2.39 (m, 2H), 3.18 (m, 1H), 3.53 (s,
4H), 3.45 (dd, J=12.1, 9.3 Hz, 1H), 3.63–3.71 (m, 2H), 3.87 (q, J=7.1 Hz,
2H), 7.19–7.38 (m, 15H). 13C-NMR (CDCl3) d: 23.3. IR (neat) cmÀ1: 3339,
3062, 2937, 2860, 2796, 1731, 1494, 1454, 1372, 1191, 1028, 748, 699. HR-MS
Calcd for C29 13CH38N2O3: m/z 475.2910. Found: m/z 475.2913 (M+). EI-MS
m/z (%): 475 (M+, 0.3), 429 (27), 384 (23), 338 (52), 210 (100), 104 (9), 91 (88).
1
[a]2D0=+30.58 (c. 1.03, CHCl3). 14: H-NMR (CDCl3) d: 1.05–1.80 (m, 6H),
2.41 (m, 2H), 3.02 (m, 1H), 3.53 (d, J=13.6 Hz, 2H), 3.55 (d, J=13.6 Hz, 2H),
3.60 (dd, J=11.3, 9.3 Hz, 1H), 3.64–3.74 (m, 2H), 7.20–7.39 (m, 15H), 7.82 (s,
1H). 13C-NMR (CDCl3) d: 23.2. IR (neat) cmÀ1: 3321, 3028, 2934, 2858, 2797,
1656, 1494, 1454, 1366, 1127, 1058, 1028, 750, 700. EI-MS m/z (%): 461 (M+,
0.7), 430 (8), 402 (16), 370 (48), 355 (23), 338 (12), 310 (11), 210 (71), 106 (11),
91 (100).
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l-[4-13C]lysine dihydrochloride (2)
Benzylamine 13 (1.44 g, 3.03 mmol) was dissolved in ethanol (20 ml), and 20%
Pd(HO)2 on carbon (4.25 g, 6.05 mmol) was added. The mixture was stirred at
608C for 39 h under a hydrogen atmosphere. The catalyst was removed by
filtration through Celite, and the filtrate was evaporated. The residue was
dissolved in water and washed three times with ether. The combined organic
layers were extracted three times with water. All aqueous layers were
combined and evaporated at 308C to give a mixture (390 mg) of lysine ethyl
ester and small amounts of lysine, partially hydrolyzed by work-up, as the
residue. The residue (314 mg) was dissolved in 6 M HCl (30 ml). The mixture
was heated at 858C for 8 h, then evaporated to give crude 2 (579 mg).
Crystallization from ethanol-ether (390 mg) gave pure l-[4-13C]lysine dihy-
drochloride (2) in 51% yield from 13. mp. 184.3–185.48C. HPLC-CD:
1
Rt=8.6 min (trace d-form gave Rt=11.0 min). H-NMR (D2O) d: 1.10–1.90
(m, 6H), 2.89 (m, 2H), 3.84 (m, 1H). 13C-NMR (D2O) d: 24.2. IR (KBr) cmÀ1
:
3423, 3100–2300 (br), 1736, 1618, 1509, 1501, 1212, 1129, 998, 821, 735.
HR-FAB-MS (glycerol) Calcd for C5 13CH14N2O2: m/z 148.0586. Found:
m/z 148.1175 (MH+). CD (pH 1.0 HClO4) l nm (De): 196 (+4.25), 211
(+2.67).
Acknowledgements
This work was supported in part by a grant for the promotion of the
advancement of education and research in graduate schools from the Ministry
of Education, Culture, Sports and Technology of Japan.
References
1. Allen J, Voges R. Synthesis and Applications of Isotopically Labelled Compounds.
Wiley: Chichester, 1994.
2. Ishii T, Furube M, Hirano S, Takatori K, Kajiwara M. Chem Pharm Bull 2001;
49: 1507–1511.
3. Iida K, Kajiwara M. Biochemistry 2000; 39: 3666–3670.
4. Takatori K, Nishihara M, Nishiyama Y, Kajiwara M. Tetrahedron 1998; 54:
15861–15869.
5. Takatori K, Nishihara M, Kajiwara M. J Label Compd Radiopharm 1999; 42:
701–708.
6. Takatori K, Toyama S, Narumi S, Fujii S, Kajiwara M. J Label Compd
Radiopharm 2004; 47: 91–94.
7. Dellaria Jr JF, Santarsiero BD. J Org Chem 1989; 54: 3916–3926.
8. Aberhart DJ, Cotting J-A. J Chem Soc, Perkin Trans I 1988; 2119–2122.
9. Yuan SS, Ajami AM. J Chin Chem Soc 1989; 36: 479–481.
10. Raap J, van der Wielen CM, Lugtenburg J. Recl Trav Chim Pays-Bas 1990; 109:
277–286.
Copyright # 2004 John Wiley & Sons, Ltd.
J Label Compd Radiopharm 2004; 47: 787–795

ASYMMETRIC SYNTHESIS OF L-[4-13C]LYSINE
795
11. Fasth K-J, Hoernfeldt K, Laangstrom B. Acta Chem Scand 1995; 49: 301–304.
12. Raap J, Wolthuis WNE, Hehenkamp JJJ, Lugtenburg J. Amino Acids 1995; 8:
171–186.
13. Sutherland A, Willis CL. J Label Compd Radiopharm 1996; 38: 95–102.
14. Lodwig SN, Unkefer CJ. J Label Compd Radiopharm 1998; 41: 983–991.
15. Kurumaya K, Okazaki T, Seido N, Akasaka Y, Kawajiri Y, Kajiwara M. J Label
Compd Radiopharm 1989; 27: 217–235.
16. Lang RW, Hansen H-J. Organic Syntheses Collective, vol. 7. Wiley: New York,
1990; 232–235.
17. Cappon JJ, Baart J, van der Walle GAM, Raap J, Lugtenburg J. Recl Trav Chim
Pays-Bas 1991; 110: 158–166.
18. Dix D, Imming P. Arch Pharm 1995; 328: 203.
19. Pasto DJ, Taylor T. Reduction with diimide. In Organic Reactions, vol. 40,
Paquette LA (ed.). Wiley: New York, 1991; 91–156.
20. Takatori K, Toyama S, Fujii S, Kajiwara M. Chem Pharm Bull 1995; 43:
1797–1799.
Copyright # 2004 John Wiley & Sons, Ltd.
J Label Compd Radiopharm 2004; 47: 787–795