Synthesis of functionalized L-cysteine and L-methionine by reaction with electron-deficient acetylenes

Article abstract of DOI:10.1055/s-0029-1217602

A novel families of nonconventionally functionalized amino acids have been synthesized in almost quantitative yields by chemo-, regio-and stereospecific addition of L-cysteine and Lmethionine to electron-deficient functionalized acetylenes (cyanoacetylene

Full text of DOI:10.1055/s-0029-1217602

3136
PAPER
Synthesis of Functionalized L-Cysteine and L-Methionine by Reaction with
Electron-Deficient Acetylenes
S
ynthesis of Func
o
tionalized
L
-
Cysteine
i
and
L
s
-Methionine A. Trofimov,* Anastasiya G. Mal’kina, Olesya A. Shemyakina, Valentina V. Nosyreva, Angela P. Borisova,
Spartak S. Khutsishvili, Leonid B. Krivdin
A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences,
1 Favorsky Str., 664033 Irkutsk, Russian Federation
Fax +7(3952)419346; E-mail: boris_trofimov@irioch.irk.ru
Received 28 April 2009; revised 7 May 2009
ceed under mild conditions to provide for isomeric purity
of the products obtained.
Abstract: A novel families of nonconventionally functionalized
amino acids have been synthesized in almost quantitative yields by
chemo-, regio- and stereospecific addition of L-cysteine and L-
methionine to electron-deficient functionalized acetylenes (cyano-
acetylenes and methyl 4-hydroxy-4-methylpent-2-ynoate) under
mild conditions (water, r.t., 2–5 h). Thus, for the first time, the un-
commonly functionalized optically active amino acids composing
of L-cysteine and L-methionine structural units along with cinnamic
acid, dihydrofuranone, iminodihydrofuran, and other biologically
important functionalities are readily available.
Here we present our findings on modifications of L-cys-
teine (1) and L-methionine (2) in their addition reactions
to electron-deficient acetylenes: 3-phenylprop-2-yneni-
trile (3), a,b-acetylenic g-hydroxy nitriles 4a–d and meth-
yl 4-hydroxy-4-methylpent-2-ynoate (5).
We have found that L-cysteine (1), under mild conditions
[acetone–water (1:2), 20–25 °C, 5 h], adds smoothly to 3-
phenylprop-2-ynenitrile (3) to quantitatively give the
chemo-, regio- and stereospecifically adduct 6, isolated in
98% yield (Scheme 1). Noteworthy, that the adduct 6 rep-
resents a combination of L-cysteine with a naturally oc-
curring (E)-cinnamic acid derivative that contributes to its
biological prospect.
Key words: alkynes, amino acids, nucleophilic addition, cycliza-
tion
Advances in proteomics stimulate the interest to the syn-
thesis of non-natural amino acids.1 By employing non-
natural amino acids, the activity of biological important
peptides can be controlled.1b,2 The demand for peptide-
based structures is increasing rapidly in drug design.1b,3
Cysteine and methionine are important amino acids for
maintaining the integrity of cellular systems by control-
ling their redox state and detoxifying harmful compounds,
including free radicals and active oxygen species.4 They
are the two principal sulfur amino acids found in mam-
mals.4,5 Cysteine proteases of the papain class, such as
cathepsin B, L, K, and S, are intensively studied in medic-
inal chemistry. They relate to osteoporosis, cancer me-
tastasis, rheumatoid arthritis, asthma, and infectious
diseases.6
O
+
_
NH3
+
O
acetone–H2O
(1:2)
NH3
O
SH
CN
S
CN
+
_
20–25 °C, 5 h
O
1
3
6, 98%
Scheme 1 Modification of L-cysteine (1) with 3-phenylprop-2-
ynenitrile (3)
To assign the configuration of adduct 6 relative to the dou-
ble bond, we have performed nonempirical calculations
(SOPPA,8 aug-cc-pVTZ-J of Sauer et al.9 for hydrogens,
cc-pCVDZ of Dunning10 for carbons11) of the one-bond
olefinic 13C-1H spin-spin coupling constant, 1JCH, and vic-
inal 13C-1H coupling involving ipso carbon of the phenyl
group and the olefinic proton, 3JCH, in both Z- and E-iso-
mers of the model compound 7.
A number of cysteine derivatives, for example, S-methyl-,
S-ethyl-, S-propyl-, S-allyl- and N-acetylcysteines, occur-
ring in garlic, display significant enzymatic antioxidant
protection and spare a-tocopherol in mice. Besides, they
diminish fibronectin, TG, and cholesterol concentrations
in plasma and liver. Hence, these compounds also possess
protective effect for cardiovascular disease.6,7
Therefore, the search for new approaches to chemical
modifications of cysteine and methionine (an essential
amino acid) to their non-natural derivatives is a rewarding
target of organic synthesis and corresponds to the modern
trends in drug discoveries. Of particular interest are highly
selective functionalizations, especially those which pro-
The calculated values were compared with the experimen-
tal couplings in adduct 6 (Table 1). All the four nonrela-
tivistic coupling contributions were taken into account,
namely, Fermi contact, JFC, spin-dipolar, JSD, diamagnetic
spin-orbital, JDSO, and paramagnetic spin-orbital, JPSO. All
the calculations were carried out using the DALTON
package12 while geometrical optimizations were per-
formed at the MP2/6-311G** level with the GAMESS
code.13
SYNTHESIS 2009, No. 18, pp 3136–3142
x
x.
x
x
.
2
0
0
9
Advanced online publication: 10.07.2009
DOI: 10.1055/s-0029-1217602; Art ID: Z08309SS
© Georg Thieme Verlag Stuttgart · New York

PAPER
Synthesis of Functionalized L-Cysteine and L-Methionine
3137
Table 1 Spin-Spin Coupling Constants of 7 Calculated at the SOPPA Level and Experimental Values for the Adduct 6a
MeS
CN
MeS
CN
(Z)-7
(E)-7
Compoundb
Coupling constant JDSO
JPSO
0.70
JSD
0.42
JFC
Jcalc
Jexp
(E)-7
1JCH
3JCH
1JCH
3JCH
1.08
170.17
10.38
176.41
6.13
172.37
10.24
178.13
6.23
–
–0.31
1.01
0.31
0.16
0.53
0.01
0.42
–
(Z)-7
178.0c
–0.15
–0.06
4.50c
a All couplings and their contributions are in Hz. Equilibrium MP2/6-311G** geometries were used throughout.
b Both isomers of 7 were adopted in their predominant conformations.
c Measured in compound 6.
1
From Table 1, it follows that both couplings demonstrate In the H and 13C NMR spectra of 8a,c,d, only single
the marked stereospecificity with respect to the configura- peaks of olefinic hydrogens (6.07–6.20 ppm) and carbons
tion at the C=C bond in 6, which allows one to unambig- (100.2–101.1 ppm) are detected, thus indicating the con-
uously assign Z-configuration to adduct 6. An additional figurational homogeneity of the compounds. For adduct
evidence of the Z-configuration of adduct 6 has been 8b, two sets of the olefinic hydrogen (6.13 and 6.14 ppm)
gained from the 2D NOESY spectrum of 6 showing cross and carbon signals are observed (100.6 and 100.8 ppm),
peak between olefinic proton (5.72 ppm) and those in the that correspond to two diastereomers. The Z-configura-
ortho-position of the phenyl group (7.47 ppm) (Figure 1).
tion of adducts 8a–d is explicitly supported by the 2D (1H,
1H) NOESY spectrum of the compound 8a, where the
cross-peak between signals of the olefin proton and meth-
yl group protons is observed (Figure 2). The configura-
tional assignment and substituent location for the
compound 8a were also based on the values of vicinal
+
NH3
CN
S
O
_
H
H
O
3
coupling constant JCH between olefinic proton and the
carbon C-4 (3JC-4,H-2 = 4.6 Hz). Since the trans-vicinal
3JCH value is always larger than the corresponding cis-3JCH
value, the H-2 atom is located in the cis-position with re-
spect to the C-4. Therefore, amino acid 8a is the Z-isomer
(Figure 2).
Figure 1 Cross-peak in the 2D (1H, 1H) NOESY NMR spectrum of
the amino acid 6
Zwitterionic form of amino acid 6 is supported by its IR
(vaseline oil) spectrum where the broad strong absorption
in the region of 3300–2500 cm–1 is observed. This absorp-
tion is commonly assigned to the +NH3 group.14 Comple-
mentary, in the spectrum, the broad band at 2040 cm–1 is
attributable to the same moiety. Carboxylate anion is
spectrally manifested by broad absorption in the region of
1650–1558 cm–1 obviously overlapping with C=C bond
stretching vibration (1592 cm–1).
Table 2 Functionalization of L-Cysteine (1) with a,b-Acetylenic g-
Hydroxy Nitriles 4
O
+
_
NH3
O
R2
H2O
N
1
R1
CN
+
S
20–25 °C, 4 h
OH
R2
R1
4a–d
a,b-Acetylenic g-hydroxy nitriles 4a–d react with L-cys-
teine (1) under the same mild conditions (water, 20–
25 °C, 4 h) in chemo-, regio- and stereospecific manner to
form optically active amino acids 8a–d of exclusive Z-
configuration in 91–98% isolated yield (Table 2).
OH
8a–d
Product
8a
R1
R2
Me
Et
Isolated yield (%)
Me
Me
98
96
91
94
For the structure determination of amino acids 8a–d, 1H,
8b
1
1
13C, H–1H homonuclear, and H–13C heteronuclear 2D
(NOESY and HMBC) NMR techniques have been em-
ployed.
8c
(CH2)4
(CH2)5
8d
Synthesis 2009, No. 18, 3136–3142 © Thieme Stuttgart · New York

3138
B. A. Trofimov et al.
PAPER
O
_
O
NH2
+
MeO
OH
NH3
HO
+
O–
S
(Z)-9
(E)-9
10
1
CN
O
S
– MeOH
2
3
HO
4
H
CH3
5
CH3
Scheme 3 Isomerization and cyclization of adduct 9
6
Figure 2 Cross-peaks in the 2D (1H, 1H) NOESY and HMBS NMR
spectra of the amino acid 8a
dihydrofuran and cysteine entities is of particular promise
for drug discovery.
Z-Stereospecificity of the additions (Scheme 1 and
Table 2) expectedly resulted from the known trans-mode
of nucleophilic attack of acetylenes.15
A similar combination of iminodihydrofuran cycle with
an essential amino acid moiety in one molecule is attained
by the addition of L-methionine (2) to a,b-acetylenic g-hy-
droxy nitriles 4a–d. As in the former cases, the reaction
proceeds under very mild conditions (water, pH ~ 8.6–9.0,
20–25 °C, 2 h), but unlike the results with L-cysteine (1)
it ends up directly with the iminodihydrofuran-modified
methionines 11a–d in 80–96% yields (Table 3).
The reaction between L-cysteine (1) and methyl 4-hy-
droxy-4-methylpent-2-ynoate (5) [acetone–water (1:2),
20–25 °C, 5 h] affords a mixture (2:1, 1H NMR) of the pri-
mary adduct (Z)-9 and dihydrofuranone 10, originated
from lactonization of adduct 9 (after its Z → E-isomeriza-
tion). Total yield of the mixture is above 95% (Scheme 2).
Table 3 Modification of L-Methionine (2) with a,b-Acetylenic g-
Hydroxy Nitriles 4
In this case, Z → E-isomerization may be facilitated by the
resonance redistribution of the double bond electron den-
sity (Scheme 3).
MeS
O
O
_
_
H2O, pH 8.6–9.0
20–25 °C, 2 h
Upon standing the mixture of 9 + 10 at ambient tempera-
ture, the component ratio 9:10 gradually changes and
reached 1:2 after 5 months (1H NMR). From this mixture,
the amino acid 10 is isolated in 60% yield, the isolated
yield of the adduct 9 (E/Z = 1:5, 1H NMR) is 30%.
S
4a–d
HN
R2
+
O
O
Me
+
NH3
+
NH2
R1
O
2
11a–d
The dihydrofuran moiety is known to be a potent structure
of numerous biological active compounds (vitamin C,16
penicillic, tetronic acids and their thiol analogues,17 anti-
AIDS drugs, such as d4T [1-(2¢,3¢-dideoxy-g-D-glycero-
pent-2-enofuranosyl)thymine] and AZT {1-[4-azido-5-
(hydroxymethyl)tetrahydrofuran-2-yl]-5-methylpyrimi-
dine-2,4-(1H,3H)-dione}18). The dihydrofuran structure
occurs in cardenolides19 (cardioactive steroid lactones), in
dysidiolide – the only known natural inhibitor of a protein
phosphatase cdc25A20 – as well as in a great variety of
other natural molecules such as sesquiterpenes21 and pul-
vinic acid derivatives,22 etc. In strigol and its analogues,
the dihydrofuranone part is primarily responsible for the
germination of seeds.23 Therefore, the combination of the
Product
11a
R1
R2
Me
Et
Isolated yield (%)
Me
Me
96
96
93
80
11b
11c
(CH2)4
(CH2)5
11d
Obviously, the primary Z-adducts A isomerize prototropi-
cally to imines B capable of cyclizing to iminotetrahydro-
furans C which are finally transformed to amino acids
11a–d (Scheme 4).
+
NH3
MeO
O
O
acetone–H2O (1:2)
20–25 °C, 5 h
_
S
O
1
+
O
OMe
OH
5
OH
(Z)-9
+
NH3
+
NH3
O
O
_
S
_
S
O
O
– MeOH
O
O
HO OMe
O
(E)-9
10
Scheme 2 Reaction of 1 with 5
Synthesis 2009, No. 18, 3136–3142 © Thieme Stuttgart · New York

PAPER
Synthesis of Functionalized L-Cysteine and L-Methionine
3139
O
O
O
SMe
CN
HO
SMe
SMe
NH
HO
HO
HN
N
N
R2
2
+ 4
11
R2
R2
R1
R1
OH
CN
R1
O
OH
A
B
C
Scheme 4 Formation of 11
13C NMR (100.62 MHz, D2O): d = 32.9 (CH2), 53.4 (CH), 98.3
(=CH), 117.4 (CN), 128.2 (C-3,5), 128.9 (C-2,6), 131.0 (C-4),
134.6 (C-1), 161.0 (SC=), 170.8 (COO–).
The unusual zwitterionic structure of amino acids 11a–d
follows from glycine addition to a,b-acetylenic g-hydroxy
nitrile 4a, where the positive charge transfer to iminodihy-
drofuran cycle is unambiguously shown by the single-
crystal X-ray analysis.24
Anal. Calcd for C12H12N2O2S: C, 58.05; H, 4.87; N, 11.28; S, 12.91.
Found: C, 57.98; H, 5.10; N, 11.05; S, 13.12.
In summary, a novel approach to chemical modification
of L-cysteine and L-methionine (an essential amino acid)
to their non-natural derivatives has been developed. The
approach comprises the chemo-, regio-, and stereospecific
addition of L-cysteine and L-methionine to electron-defi-
cient functionalized acetylenes such as cyanoacetylenes
and methyl 4-hydroxy-4-methylpent-2-ynoate under mild
conditions (aqueous media, ambient temperature). The
Amino Acids 8a–d; General Procedure
To a solution of cysteine (1; 1 mmol) in H2O (4 mL), the appropriate
a,b-acetylenic g-hydroxy nitrile 4a–d (1 mmol) was added. The
mixture was stirred at 20–25 °C for 4 h and the H2O was evaporated.
The residue was washed with Et2O (5 × 0.5 mL) and dried in vacuo
to give the amino acids 8a–d.
(2R)-2-Ammonio-3-{[(Z)-2-cyano-1-(1-hydroxy-1-methyleth-
yl)ethenyl]sulfanyl}propanoate (8a)
methodology allowed us to prepare in almost quantitative Yield: 0.225 g (98%); white microcrystalline powder; mp 102–104
°C; [a]D25 –14.2 (c 0.01, H2O).
yields novel families of optically active nonconventional-
ly functionalized amino acids incorporated L-cysteine and
L-methionine structural units along with cinnamic acid,
dihydrofuranone, iminodihydrofuran, and other biologi-
cally important functionalities. Such non-natural amino
acids are potential pharmaceuticals and promising build-
ing blocks and auxiliaries for drug design, proteomics,
and controlled peptide modification.
IR (vaseline oil, KBr): 3500–2500 with maxima at 3379, 3264,
3059, 2977, 2930, 2868, 2725, 2602 (OH, +NH3, C=CH, CH), 2209
(CN), 2064 (+NH3), 1616 (COO–), 1580 cm–1 (SC=C).
1H NMR (400.13 MHz, D2O): d = 1.36 (s, 3 H, CH3), 1.37 (s, 3 H,
CH3), 3.45 (dd, J = 7.09, 13.69 Hz, 1 H, SCH2), 3.63 (dd, J = 7.09,
13.69 Hz, 1 H, SCH2), 3.94 (dd, J = 4.40, 7.09 Hz, 1 H, CH), 6.15
(s, 1 H, =CH).
13C NMR (100.62 MHz, D2O): d = 27.7 (CH3), 35.9 (CH2), 54.0
(CH), 75.2 [C(CH3)2], 100.2 (=CH), 117.5 (CN), 170.0 (SC=),
171.5 (COO–).
All melting points were taken on a Kofler micro hot stage. Optical
rotations were measured on a Polamat A polarimeter at 25 °C. IR
spectra were measured on Bruker IFS-25 in KBr pellets and vase-
Anal. Calcd for C9H14N2O3S: C, 46.94; H, 6.13; N, 12.16; S, 13.92.
Found: C, 46.95; H, 6.37; N, 11.95; S, 13.63.
1
line oil. The H, 13C, NOESY, and HMBC NMR spectra were re-
corded on a Bruker DPX-400 spectrometer in D2O. L-Cysteine (1)
and L-methionine (2) are commercial products. 3-Phenylprop-2-
ynenitrile (3),25 a,b-acetylenic g-hydroxy nitriles 4a–d,26 and meth-
yl 4-hydroxy-4-methylpent-2-ynoate (5)27 were prepared according
to published procedures.
(2R)-2-Ammonio-3-{[(Z)-2-cyano-1-(1-hydroxy-1-methylpro-
pyl)ethenyl]sulfanyl}propanoate (8b)
Yield: 0.234 g (96%); pale yellow microcrystalline powder; mp
129–130 °C; [a]D25 –18.7 (c 0.01, H2O).
IR (vaseline oil, KBr): 3450–2500 with maxima at 3195, 3045,
2972, 2930, 2630 (OH, +NH3, C=CH, CH), 2212 (CN), 2075
(+NH3), 1625 (COO–), 1580 cm–1 (SC=C).
1H NMR (400.13 MHz, D2O): d = 0.75–0.79 (m, 3 H, CH2CH3),
1.37, 1.38 (s, 3 H, CH3), 1.71–1.73 (m, 2 H, CH2CH3), 3.50–3.72
(m, 2 H, SCH2), 3.96–3.99 (m, 1 H, CH), 6.13 and 6.14 (s, 1
H, =CH).
13C NMR (100.62 MHz, D2O): d = 7.4 (CH2CH3), 25.6, 25.7 (CH3),
32.8, 35.8, 35.9 (CH2), 54.1 (CH), 78.2 [C(CH3)2], 100.6, 100.8
(=CH), 117.7 (CN), 169.5 (SC=), 171.7 (COO–).
(2R)-2-Ammonio-3-{[(Z)-2-cyano-1-phenylethenyl]sulfa-
nyl}propanoate (6)
A solution of 3-phenylprop-2-ynenitrile (3; 0.127 g, 1 mmol) in ace-
tone (1 mL) was added to solution of cysteine (1; 0.121 g, 1 mmol)
in H2O (2 mL). After stirring the mixture at 20–25 °C for 5 h, the
stirring was stopped, and the solvents were evaporated. The residue
was washed with Et2O (5 × 0.5 mL) and dried in vacuo; yield:
0.243 g (98%); white microcrystalline powder; mp 152–153 °C;
[a]D25 –176.0 (c 0.01, 0.1 N HCl).
IR (vaseline oil, KBr): 3300–2500 with maxima at 3141, 3028,
2964, 2923, 2848 (+NH3, C=CH, CH), 2214 (CN), 2040 (+NH3),
1635 (COO–), 1613, 1592 cm–1 (SC=C).
The doubling of all the NMR signals resulted from the two diaste-
reomers.
1H NMR (400.13 MHz, D2O): d = 2.99–3.05 (dd, J = 8.04, 12.96
Hz, 1 H, SCH2), 3.10 (dd, J = 4.40, 12.96 Hz, 1 H, SCH2), 3.66 (dd,
J = 4.40, 8.04 Hz, 1 H, CH), 5.70 (s, 1 H, =CH), 7.38–7.48 (m, 5 H,
Ar).
Anal. Calcd for C10H16N2O3S: C, 49.16; H, 6.60; N, 11.47; S, 13.12.
Found: C, 48.91; H, 6.65; N, 11.64; S, 12.98.
Synthesis 2009, No. 18, 3136–3142 © Thieme Stuttgart · New York

3140
B. A. Trofimov et al.
PAPER
(2R)-2-Ammonio-3-{[(Z)-2-cyano-1-(1-hydroxycyclopen-
tyl)ethenyl]sulfanyl}propanoate (8c)
13C NMR (100.62 MHz, D2O): d = 28.79, 28.82 (CH3), 37.2, 37.6
(CH2), 53.3, 53.8 (OCH3), 54.8, 56.6 (CH), 76.4, 79.7 [C(CH3)2],
118.6, 121.4 (=CH), 161.3, 163.0, 168.8, 169.0 (C=O), 172.5, 172.9
(SC=).
Yield: 0.233 g (91%); pale yellow microcrystalline powder; mp
156–158 °C; [a]D25 –11.5 (c 0.01, H2O).
IR (vaseline oil, KBr): 3500–2500 with maxima at 3270, 3100,
3052, 2965, 2872, 2586 (OH, +NH3, C=CH, CH), 2215 (CN), 2070
(+NH3), 1616 (COO–), 1584 cm–1 (SC=C).
Anal. Calcd for C10H17NO5S: C, 45.61; H, 6.51; N, 5.32; S, 12.18.
Found: C, 45.49; H, 6.59; N, 5.43; S, 12.25.
(2R)-2-Ammonio-3-[(2,2-dimethyl-5-oxo-2,5-dihydro-3-fura-
nyl)sulfanyl]propanoate (10)
1H NMR (400.13 MHz, D2O): d = 1.64–1.74, 1.94 (m, 8 H, CH2-cy-
clopentyl), 3.52 (dd, J = 7.09, 13.94 Hz, 1 H, SCH2), 3.65 (dd,
J = 4.40, 13.94 Hz, 1 H, SCH2), 3.96 (dd, J = 4.40, 7.09 Hz, 1 H,
CH), 6.20 (s, 1 H, =CH).
Yield: 0.139 g (60%); white microcrystalline powder; mp 183–185
°C; [a]D25 +10.1 (c 0.01, H2O).
IR (KBr): 3250–2500 with maxima at 3127, 3076, 2982, 2930,
2889, 2691, 2564, 2466 (OH, +NH3, C=CH, CH), 2207–2132
(+NH3), 1709, 1658, 1613 cm–1 (COO–, C=O, SC=C).
1H NMR (400.13 MHz, D2O): d = 1.37 (s, 6 H, CH3), 3.33 (dd,
J = 7.68, 14.34 Hz, 1 H, SCH2), 3.47 (dd, J = 4.16, 14.27 Hz,1 H,
SCH2), 3.92 (dd, J = 4.16, 7.36 Hz, 1 H, CH), 5.80 (s, 1 H, =CH).
13C NMR (100.62 MHz, D2O): d = 23.3, 23.4, 36.0, 38.7 (CH2),
54.1 (CH), 85.8 (C-cyclopentyl), 100.8 (=CH), 117.6 (CN), 168.2
(SC=), 171.6 (COO–).
Anal. Calcd for C11H16N2O3S: C, 51.55; H, 6.29; N, 10.93; S, 12.51.
Found: C, 51.31; H, 6.39; N, 10.86; S, 12.39.
(2R)-2-Ammonio-3-{[(Z)-2-cyano-1-(1-hydroxycyclohex-
yl)ethenyl]sulfanyl}propanoate (8d)
13C NMR (100.62 MHz, D2O): d = 25.0, 25.1 (CH3), 32.5 (CH2),
52.5 (CH), 88.7 (CCH3), 107.7 (=CH), 171.1, 173.0 (C=O), 177.2
(SC=).
Yield: 0.254 g (94%); pale yellow microcrystalline powder; mp
164–166 °C; [a]D25 –15.6 (c 0.01, H2O).
Anal. Calcd for C9H13NO4S: C, 49.74; H, 5.67; N, 6.06; S, 13.87.
Found: C, 49.87; H, 5.57; N, 5.99; S, 13.78.
IR (vaseline oil, KBr): 3520–2500 with maxima at 3277, 3056,
2936, 2858, 2595 (OH, +NH3, C=CH, CH), 2211 (CN), 2043
(+NH3), 1616 (COO–), 1584 cm–1 (SC=C).
Amino Acids 11a–d; General Procedure
To a solution of methionine (2; 0.149 g, 1 mmol) and NaOH (0.01
g, 0.25 mmol) in H2O (1 mL) was added the appropriate a,b-acety-
lenic g-hydroxy nitrile 4a–d (1 mmol). After stirring the mixture at
20–25 °C for 2 h, the stirring was stopped, and the H2O was evapo-
rated. The residue obtained was passed through neutral Al2O3 (2–3
cm, eluent: 50–70 mL of EtOH). The solvent was evaporated in
vacuo to give amino acids 11a–d.
1H NMR (400.13 MHz, D2O): d = 1.05–1.06, 1.40–1.46 and 1.58–
1.65 (m, 10 H, CH2-cyclohexyl), 3.40 (dd, J = 7.09, 13.94 Hz, 1 H,
SCH2), 3.50 (dd, J = 4.16, 13.94 Hz, 1 H, SCH2), 3.83 (dd,
J = 4.16, 7.09 Hz, 1 H, CH), 6.07 (s, 1 H, =CH).
13C NMR (100.62 MHz, D2O): d = 21.1, 24.5, 34.7 and 36.2 (CH2),
54.1 (CH), 76.7 (C-cyclohexyl), 101.1 (=CH), 117.8 (CN), 170.6
(SC=), 171.6 (COO–).
(2S)-2-[(5-Iminio-2,2-dimethyl-2,5-dihydro-3-furanyl)amino]-
4-(methylsulfanyl)butanoate (11a)
Anal. Calcd for C12H18N2O3S: C, 53.31; H, 6.71; N, 10.36; S, 11.86.
Found: C, 53.08; H, 6.84; N, 10.28; S, 12.02.
Yield: 0.248 g (96%); yellow microcrystalline powder; mp 138–141
°C; [a]D25 –43.5 (c 0.01, H2O).
Reaction of L-Cysteine (1) with Methyl 4-Hydroxy-4-methyl-
pent-2-ynoate (5)
IR (vaseline oil, KBr): 3450–2600 with maxima at 3215, 3059,
2979, 2923, 2875 (NH, =+NH2, C=CH, CH), 1687, 1617 cm–1
(COO–, C=C).
1H NMR (400.13 MHz, D2O): d = 1.50 (s, 3 H, CH3), 1.52 (s, 3 H,
CH3), 1.99 (s, 3 H, SCH3), 1.94–2.11 (m, 2 H, SCH2), 2.37–2.58 (m,
2 H, CH2), 3.85 (dd, J = 4.99, 8.45 Hz, 1 H, CH), 4.91 (s, 1
H, = CH).
13C NMR (100.62 MHz, D2O): d = 14.0 (SCH3), 23.4, 23.8 (CH3),
29.6, 30.3 (CH2), 59.7 (CH), 76.5 (CCH3), 91.3 (=CH), 175.9, 176.9
(=CN, C=NH), 177.1 (COO–).
A solution of methyl 4-hydroxy-4-methyl-2-pentynoate (5; 0.142 g,
1 mmol) in acetone (1 mL) was added to solution of cysteine (1;
0.121 g, 1 mmol) in H2O (2 mL). After stirring the mixture at 20–
25 °C for 5 h, the stirring was stopped, and solvents were evaporat-
ed. The residue was washed with Et2O (5 × 0.5 mL) to give 0.25 g
(95%) of a mixture of amino acids 9 (0.166 g) and 10 (0.083 g), (2:1,
1H NMR) The proportion changed to 1:1 in a month, and in 5
months the composition of the reaction mixture 9:10 changed to 1:2.
The mixture was washed with EtOH (4 × 1 mL), the insoluble resi-
due was dried in vacuo to give compound 10. After evaporation of
1
EtOH in vacuo, a mixture of E- and Z-isomers (1:5, H NMR) of
Anal. Calcd for C11H18N2O3S: C, 51.14; H, 7.02; N, 10.84; S, 12.41.
Found: C, 50.93; H, 7.21; N, 10.78; S, 12.64.
compound 9 was obtained.
(2R)-2-Ammonio-3-{[(E,Z)-1-(1-hydroxy-1-methylethyl)-3-
methoxy-3-oxo-1-propenyl]sulfanyl}propanoate (9)
Yield: 0.079 g (30%); yellow microcrystalline powder; mp 96–98
°C.
(2S)-2-[(2-Ethyl-5-iminio-2-methyl-2,5-dihydro-3-furanyl)ami-
no]-4-(methylsulfanyl)butanoate (11b)
Yield: 0.261 g (96%); yellow microcrystalline powder; mp 160–163
°C; [a]D25 –52.4 (c 0.01, EtOH).
IR (KBr): 3500–2500 with maxima at 3264, 3080, 2979, 2943,
IR (KBr): 3490–2670 with maxima at 3386, 3218, 3052, 2973, 2923
(NH, =+NH2, C=CH, CH), 1689, 1616 cm–1 (COO–, C=C).
1H NMR (400.13 MHz, D2O): d = 0.63–0.68 (m, 3 H, CH3CH2),
1.45, 1.47 (s, 3 H, CH3), 1.96 (s, 3 H, SCH3), 1.75–2.02 (m, 4 H,
CH2CH3, SCH2), 2.34–2.54 (m, 2 H, CH2), 3.79–3.84 (m, 1 H, CH),
4.95 (s, 1 H, =CH).
13C NMR (100.62 MHz, D2O): d = 6.2, 6.3 (CH2CH3), 14.1, 14.2
(SCH3), 22.7, 22.9 (CH3), 29.7, 30.2, 30.3, 30.5 (CH2), 59.8, 59.9
(CH), 78.2 (CCH3), 94.2 (=CH), 175.8, 175.9, 176.5, 177.0, 177.1
(C=O, C=NH, =CN).
2875, 2548 (OH, +NH3, C=CH, CH), 2090 (NH3 ), 1714, 1613 cm–1
+
(COO–, C=O, SC=C).
1H NMR (400.13 MHz, D2O): d = 1.31 (s, 3 H, CH3), 1.32 [s, 3 H,
CH3, (Z)-9], 1.34 (s, 3 H, CH3), 1.35 [s, 3 H, CH3, (E)-9], 3.08 [dd,
J = 7.94, 14.06 Hz, 1 H, SCH2, (E)-10], 3.19 [dd, J = 7.39, 16.18
Hz, 2 H, SCH2, (E,Z)-9], 3.34 [dd, J = 3.79, 14.19 Hz, 1 H, SCH2,
(Z)-9], 3.64, 3.66 (s, 3 H, OCH3), 3.85 [dd, J = 3.84, 7.55 Hz, 1 H,
CH, (Z)-9], 3.94 [dd, J = 4.1, 8.36 Hz,1 H, CH, (E)-9], 6.44, 6.47
(s, 1 H, =CH).
Synthesis 2009, No. 18, 3136–3142 © Thieme Stuttgart · New York

PAPER
Synthesis of Functionalized L-Cysteine and L-Methionine
3141
The doubling of all the NMR signals resulted from the two diaste-
reomers.
(6) (a) Zhou, N. E.; Reddy, A. V. N.; Kaleta, J.; Micetich, R. G.;
Singh, R. ARKIVOC 2001, (vi), 116. (b) Mashkovskii, M.
D. Drugs (in Russian); Novaya Volna: Moscow, 2003.
(c) Hsu, C.-C.; Huang, C.-N.; Hung, Y.-C.; Yin, M.-C.
J. Nutr. 2004, 134, 149. (d) Ali, V.; Nozaki, T. Clinical
Microbiol. Rev. 2007, 164; and references cited therein.
(e) Oda, H. J. Nutr. 2006, 136, 1666S.
(7) Riedijk, M. A.; Stoll, B.; Chacko, S.; Schierbeek, H.;
Sunehag, A. L.; van Goudoever, J. B.; Burrin, D. G. Proc.
Natl. Acad. Sci. U.S.A. 2007, 104, 3408.
Anal. Calcd for C12H20N2O3S: C, 52.92; H, 7.40; N, 10.29; S, 11.77.
Found: C, 52.89; H, 7.64; N, 10.54; S, 11.94.
(2S)-2-[(2-Iminio-1-oxaspiro[4.4]non-3-en-4-yl)amino]-4-
(methylsulfanyl)butanoate (11c)
Yield: 0.264 g (93%); yellow microcrystalline powder; mp 169–171
°C; [a]D25 –28.0 (c 0.01, EtOH).
IR (KBr): 3450–2650 with maxima at 3216, 3052, 2962, 2930, 2875
(NH, =+NH2, C=CH, CH), 1681, 1612 cm–1 (COO–, C=C).
(8) Enevoldsen, T.; Oddershede, J.; Sauer, S. P. A. Theor.
Chem. Acc. 1998, 100, 275.
1H NMR (400.13 MHz, D2O): d = 1.81 (m, 4 H, CH2), 1.97 (s, 3 H,
SCH3), 1.92–2.07 (m, 6 H, SCH2, CH2), 2.38–2.54 (m, 2 H, CH2),
3.86 (dd, J = 4.74, 8.70 Hz, 1 H, CH), 4.96 (s, 1 H, =CH).
13C NMR (100.62 MHz, D2O): d = 14.3 (SCH3), 24.4, 24.5, 29.9,
30.6, 37.3, 37.9 (CH2), 60.0 (CH), 78.2 (C-cyclopentyl), 101.4
(=CH), 174.9, 176.1, 177.3 (C=O, C=NH, =CN).
(9) Provasi, P. F.; Aucar, G. A.; Sauer, S. P. A. J. Chem. Phys.
2001, 115, 1324.
(10) Woon, D. E.; Dunning, T. H. Jr. J. Chem. Phys. 1995, 103,
4572.
(11) Sauer, S. P. A.; Krivdin, L. B. Magn. Reson. Chem. 2004, 42,
671.
(12) Angeli, C.; Bak, K. L.; Bakken, V.; Christiansen, O.;
Cimiraglia, R.; Coriani, S.; Dahle, P.; Dalskov, E. K.;
Enevoldsen, T.; Fernandez, B.; Haettig, C.; Hald, K.;
Halkier, A.; Heiberg, H.; Helgaker, T.; Hettema, H.; Jensen,
H. J. A.; Jonsson, D.; Joergensen, P.; Kirpekar, S.; Klopper,
W.; Kobayashi, R.; Koch, H.; Ligabue, A.; Lutnaes, O. B.;
Mikkelsen, K. V.; Norman, P.; Olsen, J.; Packer, M. J.;
Pedersen, T. B.; Rinkevicius, Z.; Rudberg, E.; Ruden, T. A.;
Ruud, K.; Salek, P.; Sanchez de Meras, A.; Saue, T.; Sauer,
S. P. A.; Schimmelpfennig, B.; Sylvester-Hvid, K. O.;
Taylor, P. R.; Vahtras, O.; Wilson, D. J.; Ågren, H. Dalton:
A Molecular Electronic Structure Program 2005, Release
2.0; http://www.kjemi.uio.no/software/dalton/dalton.html.
(13) Schmidt, M. W.; Baldridge, K. K.; Boatz, J. A.; Elbert, S. T.;
Gordon, M. S.; Jensen, J. H.; Koseki, S.; Matsunaga, N.;
Nguyen, K. A.; Su, S. J.; Windus, T. L.; Dupuis, M.;
Montgomery, J. A. J. Comput. Chem. 1993, 14, 1347.
(14) Silverstein, R.; Bassler, G.; Morril, T. Spectrometric
Identification of Organic Compounds; Wiley: New York,
1974.
Anal. Calcd for C13H20N2O3S: C, 54.91; H, 7.09; N, 9.85; S, 11.27.
Found: C, 54.69; H, 7.28; N, 9.57; S, 11.04.
(2S)-2-[(2-Iminio-1-oxaspiro[4.5]dec-3-en-4-yl)amino]-4-
(methylsulfanyl)butanoate (11d)
Yield: 0.238 g (80%); yellow microcrystalline powder; mp 183–185
°C; [a]D25 –21.1 (c 0.01, EtOH).
IR (KBr): 3490–2600 with maxima at 3216, 3032, 2934, 2861
(NH, =+NH2, C=CH, CH), 1684, 1614 cm–1 (COO–, C=C).
1H NMR (400.13 MHz, D2O): d = 1.26–1.29, 1.57–1.87 (m, 10 H,
CH2), 2.05 (s, 3 H, SCH3), 2.01–2.17 (m, 2 H, SCH2), 2.44–2.62 (m,
2 H, CH2), 3.91 (dd, J = 4.74, 8.45 Hz, 1 H, CH), 4.99 (s, 1
H, =CH).
13C NMR (100.62 MHz, D2O): d = 14.0 (SCH3), 21.1, 21.2, 23.2,
29.5, 30.3, 32.5, 33.1 (CH2), 59.6 (CH), 76.7 (C-cyclohexyl), 92.9
(=CH), 176.01, 176.69, 176.92 (C=O, C=NH, =CN).
Anal. Calcd for C14H22N2O3S: C, 56.35; H, 7.43; N, 9.39; S, 10.74.
Found: C, 56.58; H, 7.26; N, 9.10; S, 10.58.
(15) (a) Miller, S. I.; Tanaka, R. In Selective Organic
Transformation, Vol. 1; Thyagarajan, B. S., Ed.; Wiley-
Interscience: New York, 1970, 143. (b) Dickstein, J. I.;
Miller, S. I. In The Chemistry of the Carbon-Carbon Triple
Bond, Part 2; Patai, S., Ed.; Wiley: New York, 1978, 814.
(16) Tahir, H.; Hindsgaul, O. J. Org. Chem. 2000, 65, 911.
(17) (a) Effenberger, F.; Syed, J. Tetrahedron: Asymmetry 1998,
9, 817. (b) Shenoy, G.; Kim, P.; Goodwin, M.; Nguyen, Q.-
A.; Barry, C. E.; Dowd, C. S. Heterocycles 2004, 63, 519.
(c) Rajaram, A. R.; Pu, L. Org. Lett. 2006, 8, 2019.
(d) Zografos, A. I.; Georgiadis, D. Synthesis 2006, 3157.
(18) (a) Gao, W. Y.; Agbaria, R.; Driscoll, J. S.; Mitsuya, H.
J. Biol. Chem. 1994, 269, 12633. (b) Meier, C. Synlett 1998,
233. (c) Saboulard, D.; Naesens, L.; Cahard, D.; Salgado,
A.; Pathirana, R.; Velazquez, S.; Mcguigan, Ch.; De Clercq,
E.; Balzarin, J. Mol. Pharmacol. 1999, 56, 693.
Acknowledgment
The work was carried out under financial support of the Russian
Foundation of Basic Research (Grants No 05-03-32290, 08-03-
00021), State Contract of the Presidium of the Russian Academy of
Sciences (Program 18), Integration Scientific Project 5.1.8., and In-
tegration Project No. 54.
References
(1) (a) Twyman, R. M. Principles of Proteomics; BIOS
Scientific: New York, 2004. (b) Zhao, L.; Li, C.-J. Angew.
Chem. Int. Ed. 2008, 47, 7075.
(2) (a) Seebach, D.; Beck, A. K.; Studer, A. In Modern Synthetic
Methods, Vol. 7; Ernst, B.; Leumann, C., Eds.; VCH:
Weinheim, 1995, 1. (b) Kotha, S.; Lahiri, K. Bioorg. Med.
Chem. Lett. 2001, 11, 2887.
(3) (a) Pillai, O.; Panchagnula, R. Drug Discovery Today 2001,
6, 1056. (b) Carrell, R. W.; Lomas, D. A. Lancet 1997, 350,
134. (c) Cochran, A. G. Chem. Biol. 2000, 7, R85.
(d) van Hest, J. C. M.; Tirrel, D. A. Chem. Commun. 2001,
1897.
(4) Wang, X.; Guo, Z. Anticancer Agents Med. Chem. 2007, 7,
19.
(5) (a) Drabkin, H. J.; RajBhandary, U. L. Mol. Cell. Biol. 1998,
18, 5140. (b) Brosnan, J. T.; Brosnan, M. E. J. Nutr. 2006,
136, 1636S.
(d) Bradshaw, P. C.; Li, J.; Samuels, D. C. Biochem. J. 2005,
392, 363.
(19) Lichtenthaler, F. W.; Cuny, E.; Sakanaka, O. Angew. Chem.
Int. Ed. 2005, 44, 4944; Angew. Chem. 2005, 117, 5024.
(20) (a) Gunasekera, S. P.; McCarthy, P. J.; Kelly-Borges, M.
J. Am. Chem. Soc. 1996, 118, 8759. (b) Corey, E. J.;
Roberts, B. E. J. Am. Chem. Soc. 1997, 119, 12425.
(c) Takahashi, M.; Dodo, K.; Sugimoto, Y.; Aoyagi, Y.;
Yamada, Y.; Hasimoto, Y.; Shirai, R. Bioorg. Med. Chem.
Lett. 2000, 10, 2571. (d) Miyaoka, H.; Kajiwara, Y.; Hara,
Y.; Yamada, Y. J. Org. Chem. 2001, 66, 1429. (e) Brohm,
D.; Philippe, N.; Metzger, S.; Bhargava, A.; Muller, O.;
Lieb, F.; Waldmann, H. J. Am. Chem. Soc. 2002, 124, 13171.
Synthesis 2009, No. 18, 3136–3142 © Thieme Stuttgart · New York

3142
B. A. Trofimov et al.
PAPER
(25) Skvortsov, Yu. M.; Mal’kina, A. G.; Volkov, A. N.;
(21) (a) Soriente, A.; Crispino, A.; De Rosa, M.; De Rosa, S.;
Scettri, A.; Scognamiglio, G.; Villano, R.; Sodano, G. Eur.
J. Org. Chem. 2000, 943. (b) Basabe, P.; Delgado, S.;
Marcos, I. S.; Diez, D.; Diego, A.; De Roman, M.; Urones,
J. G. J. Org. Chem. 2005, 70, 9480.
Trofimov, B. A.; Oleinikova, E. B.; Kazin, I. V.; Gedymin,
V. V. Izv. Akad. Nauk SSSR, Ser. Khim. 1978, 872; Chem.
Abstr. 1978, 89, 24231q.
(26) (a) Landor, S. R.; Demetriou, B.; Grzeskowiak, R.; Pavey,
D. J. Organomet. Chem. 1975, 93, 129. (b) Trofimov, B.
A.; Andriyankova, L. V.; Shaikhudinova, S. I.; Kazantseva,
T. I.; Mal’kina, A. G.; Zhivet’ev, S. A.; Afonin, A. V.
Synthesis 2002, 853.
(27) (a) Trofimov, B. A.; Skvortsov, Yu. M.; Mal’kina, A. G.;
Gritsa, A. I. Zh. Org. Khim. 1985, 21, 2020; Chem. Abstr.
1986, 105, 78491s. (b) Trofimov, B. A.; Mal’kina, A. G.;
Gritsa, A. I.; Skvortsov, Yu. M.; Stankevich, V. K.;
Sokolyanskaya, L. V. Zh. Obshch. Khim. 1996, 66, 106;
Chem. Abstr. 1997, 126, 18567v.
(22) (a) Mangnus, E. M.; Stommen, P. L. A.; Zwanenburg, B.
J. Plant Growth Regul. 1992, 11, 91. (b) Kuad, P.;
Borkovec, M.; Murr, M. D.-E.; Le Gall, T.; Mioskowski,
Ch.; Spiess, B. J. Am. Chem. Soc. 2005, 127, 1323.
(23) (a) Mangnus, E. M.; Zwanenburg, B. J. Agric. Food Chem.
1992, 40, 1066. (b) Thuring, J. W. J. F.; van Gaal, A. A. M.
A.; Hornes, S. J.; de Kok, M. M.; Nefkens, G. H. L.;
Zwanenburg, B. J. Chem. Soc., Perkin Trans. 1 1997, 767.
(24) Trofimov, B. A.; Mal’kina, A. G.; Shemyakina, O. A.;
Borisova, A. P.; Nosyreva, V. V.; Dyachenko, O. A.;
Kazheva, O. N.; Alexandrov, G. G. Synthesis 2007, 2641.
Synthesis 2009, No. 18, 3136–3142 © Thieme Stuttgart · New York