Racemization-free synthesis of S-alkylated cysteines via thiol-ene reaction

Article abstract of DOI:10.1021/jo800198s

(Chemical Equation Presented) Treatment of differently protected and unprotected cysteines with a variety of alkenes in the presence of a radical initiator (AIBN) afforded the corresponding S-alkylated cysteines in high yields and without racemization.

Full text of DOI:10.1021/jo800198s

Supporting Info for
Racemization-free synthesis of S-alkylated cysteines via thiol-ene reaction
Gemma Triola,§‡ Luc Brunsveld,§† Herbert Waldmann§‡*
§Max Planck Institute of Molecular Physiology, Department of Chemical Biology, Otto Hahn Straße 11, 44227
Dortmund, Germany
‡ TU Dortmund, Department of Chemistry, Otto Hahn Straße 6, 44227 Dortmund, Germany
†Chemical Genomics Centre of the Max Planck Society, Otto Hahn Straße 15, 44227, Dortmund, Germany
Supporting Information
Table of Contents:
General Considerations
S2
General procedure for the alkylation by means of the thiol-ene reaction of Cysteine
Experimental procedures and characterization of products
Selected NMR Data
S2
S3
S10
S10
S11
S12
S13
S14
S15
S16
S17
S18
S19
S20
1H-NMR (400 MHz, CDCl3) of 3
13C-NMR (100 MHz, CDCl3) of 3
1H-NMR (400 MHz, CDCl3) of 4
1H-NMR (400 MHz, CDCl3) of 5
13C-NMR (100 MHz, CDCl3) of 5
1H-NMR (400 MHz, CD3OD) of 6
1H-NMR (400 MHz, CDCl3) of 7
1H-NMR (400 MHz, CD3OD) of 8a/8b
1H-NMR (400 MHz, CDCl3) of 9
1H-NMR (400 MHz, CDCl3/CD3OD) of 10
1H-NMR (400 MHz, CDCl3/CD3OD) of 12
S1

General considerations. NMR spectra were calibrated to the solvent signals of CDCl3
(δ=7.26 and 77.00 ppm) or CD3OD (δ=3.31 and 49.05 ppm). The following abbreviations are
used to indicate signal multiplicities: s (singlet), d (doublet), t (triplet), q (quartet), quint
(quintet), sext (sextet), sept (septet), br (broad), ap (apparent). LCMS was performed using a
gradient of 60% acetonitrile to 100% acetonitrile in 10 min. Chiral HPLC analysis was
performed with a Chiralcel OD-R column.
General procedure for the alkylation of cysteine by means of the thiol-ene reaction.
The solvent was degassed under an Argon stream in a sonicator bath for 15 min. prior to use.
To a solution of cysteine in solvent (0.26 M), 3 equivalents of alkene and 0.5 equivalents of
AIBN were added and the mixture was brought to reflux at 90 ºC until TLC analysis of the
crude reaction mixture indicated that the cysteine had been completely consumed. The
solution was allowed to cool to room temperature and the solvent was removed under reduced
pressure. The resulting residue was purified by flash chromatography to provide the desired
product (0.1 eq of AIBN has been also used, giving similar reaction yields).
S2

Experimental procedures and characterization of products
O
H2N
OCH3
S
(CH2)14CH3
(L)-2-Amino-3-hexadecylsulfanyl-propionic acid methyl ester (2). Radical alkylation was
performed with L-cysteine methyl ester hydrochloride (0.58 g; 3.37 mmol) and hexadecene in
dichloroethane (DCE) (12 mL). The reaction was complete after refluxing at 90 ºC for 3 h,
then the solution was cooled to r.t. and the solvent was removed under reduced pressure.
Compound 2 (1.1 g; 91%) was obtained after purification of the residue by flash column
1
chromatography using a CH2Cl2:MeOH mixture (9:1) as a eluent. Analytical data: H-NMR
(400 MHz, CD3OD): 0.86 (t, 3H, J= 6.8 Hz), 1.2-1.4 (m, 22H), 1.39 (t, 2H, J= 6.8 Hz), 1,60
(q, 2H, J= 7.2 Hz), 2.56 (t, 2H, J= 7.2 Hz), 3.05 (dd, 1H J= 7.2, 14.4 Hz), 3.10 (dd, 1H, J=
4.4, 14.4 Hz), 3.84 (s, 3H), 4.19 (dd, 1H, J= 4.4, 6.8 Hz), 4.73 (bs, 2H); 13C-NMR (100 MHz,
CD3OD): 14.1, 22.6, 28.7, 29.2, 29.31, 29.35, 29.50, 29.55, 29.60, 29.63, 29.65, 29.68, 29.7,
32
31.9, 32.7, 33.4, 53.0, 170.0; LC-MS (ESI): calcd for C20H42O2N1 S1: 360.29308 [M+H] +,
+
32
found 360.15 [M+H] , Rt 1.35 min; ES MS: m/z: calcd for C20H42O2N1 S1: 360.29308
[M+H] +; found: 360.29321 [M+H] +.
O
H
N
Fmoc
OCH3
(CH2)14CH3
S
(L)-(9H-Fluoren-9-ylmethoxycarbonylamino)-3-hexadecylsulfanyl-propionic
methyl ester (3)
acid
• Radical alkylation method using AIBN as initiator. Radical alkylation was
performed with L-cysteine methyl ester hydrochloride (0.58 g; 3.37 mmol) and
hexadecene in DCE (12 mL). The reaction was complete after refluxing at 90 ºC for 3
h. Then the solution was cooled to r.t. and the solvent was removed under reduced
pressure. The residue was dissolved in dioxane:H2O 1:1 (100 mL) and Na2CO3 (0.91
g; 8.73 mmol) and Fmoc-OSu (1.17 g; 3.48 mmol) were added at 0 ºC. The mixture
was stirred at this temperature for 10 min and 3 h at r.t. after which it was poured into
water (50 mL) and washed 3 times with ethyl acetate. The combined organic phases
were dried with Na2SO4, filtered, and the solvent was removed under reduced
pressure. The residue was purified by flash chromatography using a mixture
S3

cyclohexane:ethyl acetate (9:1) and giving compound 3 in 71% overall yield (1.24 g)
after two steps.
• Using UV light as a initiator. L-cysteine methyl ester hydrochloride (0.5 g; 2.91
mmol) and hexadecene (2.50 mL; 8.73 mmol) in DMF (3 mL, 0.97 M) were shaken in
a light reactor (UV light, 254 nm) at 40 ºC for 24h. The solvent was removed under
reduced pressure and Fmoc protection was performed in the mentioned conditions.
After column chromatography compound 3 was isolated (0.25 g; 15%). Analytical
data: 1H-NMR (400 MHz, CDCl3): 0.88 (t, 3H, J= 6.8 Hz), 1.2-1.4 (m, 24H), 1.57 (q,
2H, J= 7.2 Hz), 2.52 (t, 2H, J= 7.6 Hz), 2.99 (d, J= 4.4 Hz), 3.78 (t, 3H), 4.24 (t, 2H,
J= 7.2 Hz), 4.39 (d, 1H, J= 7.2 Hz), 4.61 (dd, 1H, J= 5.2, 12.8 Hz), 5.62 (d, 1H, J= 8
Hz), 7.32 (t, 2H, J= 7.2 Hz), 7.40 (t, 2H, J= 7.2 Hz), 7.60 (d, 2H, J=6.4 Hz), 7.76 (d,
2H, J= 7.2 Hz). 13C-NMR (100 MHz, CDCl3): 14.1, 22.6, 28.7, 29.2, 29.3, 29.51,
29.55, 29.59, 29.64, 19.66, 29.68, 31.9, 32.8, 34.4, 47.1, 52.6, 53.6, 67.2, 119.9, 125.1,
20
127.0, 127.7, 141.2, 143.7, 156.6, 171.3; [α]D
+6.71 (c 0.65, CH2Cl2); LC-MS
32
(ESI): calcd for C35H52O4N1 S1: 582.36116 [M+H] +, found 582.24 [M+H] +, Rt 10.77
32
min; ES MS: m/z: calcd for C35H52O4N1 S1: 582.36116 [M+H] +; found: 582.36083
[M+H] +.
O
H
N
Fmoc
OtBu
(CH2)14CH3
S
(L)-9H-Fluoren-9-ylmethoxycarbonylamino)-3-hexadecylsulfanyl-propionic acid tert-
butyl ester (5)
• From Cystine-OtBu. NEt3 (0,42 mL; 3 mmol) was slowly added to a solution of
cystine-OtBu hydrochloride (0.63 g, 1.5 mmol) and DTT (0.92 g, 6 mmol) in CH2Cl2
(15 mL). The reaction mixture was stirred overnight at r.t. and subsequently poured
into H2O (15 mL). After washing two times with H2O (15 mL), the organic phase was
dried with Na2SO4, filtered, and the solvent was removed under reduced pressure. The
residue was solved in 10 mL DCE and the radical alkylation was performed under the
general described conditions. After removing the solvent under reduced pressure the
residue was dissolved in a 1:1 dioxane:H2O mixture (100 mL) and Na2CO3 (0.95 g; 9
mmol). Subsequently, Fmoc-OSu (1.21 g; 3.6 mmol) was added and the mixture was
stirred at r.t. for 3h. After this time, ethyl acetate (50 mL) was added and the combined
organic phase was washed with H2O (50 mL). The residue was purified by flash
S4

chromatography using a mixture of cyclohexane:ethyl acetate (9:1) as eluent to obtain
5 ( 1.05 g; 57%).
• From Fmoc-Cystine-OtBu. Fmoc-cystine-OtBu was obtained by Fmoc protection of
cystine-OtBu following conditions reported in the literature.1 After reduction of the
disulfide bond of Fmoc-cystine-OtBu (0.5 g; 0.62 mmol) under the conditions reported
above, radical alkylation was performed under the general conditions described using
DCE as solvent. After purification by column chromatography (cyclohexane:ethyl
1
acetate (9:1)) compound 5 was isolated pure (0.3 g; 42%). Analytical data: H-NMR
(400 MHz, CDCl3): 0.90 (t, 3H, J= 6.8 Hz), 1.4-1.2 (m, 24H), 1.44 (s, 4.5 H), 1.51 (s,
4.5 H), 1.58 (t, 2H, J= 7.2 Hz), 2.56 (t, 2H, J= 7.6 Hz), 2.98 (dd, J= 5.6, 13.6 Hz ),
3.03 (dd, J= 5.2, 12.4 Hz), 4.24 (t, 2H, J= 7.2 Hz), 4.53 (q, 1H, J= 4.8 Hz), 5.70 (d,
1H, J= 7.6 Hz), 7.30 (dt, 2H, J= 1.2, 7.6 Hz), 7.40 (t, 2H, J= 7.2 Hz), 7.61 (d, 2H, J=
7.2 Hz), 7.75 (d, 2H, J= 7,6 Hz); 13C-NMR (100 MHz, CDCl3): 14.0, 22.6, 26.8, 27.9,
28.7, 29.1, 29.3, 29.4, 29.5, 20.60, 29.61, 29.63, 31.8, 33.0, 34.6, 47.0, 54.2, 67.1,
20
82.6, 119.8, 125.0, 126.9, 127.6, 141.2, 143.7, 143.8, 155.6, 169.7; [α]D -2.4 (c 2,
32
CH2Cl2); LC-MS (ESI): calcd for C38H58O4N1 S1: 568.35 [M+H-tBu] +, found 568.23
+
32
[M+H-tBu] , Rt 11.79 min; ES MS: m/z: calcd for C38H58O4N1 S1 [M+H]+:
624.40811; found: 624.40808 [M+H] +.
O
H
N
Fmoc
OH
(CH2)14CH3
S
(L)-9H-Fluoren-9-ylmethoxycarbonylamino)-3-hexadecylsulfanyl-propionic acid (4)
• By Hydrolysis of 3 methyl ester. AlCl3 (0.5 g; 3.80 mmol) was added to a solution of
3 (0.32 g; 0.54 mmol) in CH2Cl2 (4 mL), after 2 min dimethylaniline (DMA) (0.756
mL; 5.94 mmol) was added and the reaction mixture was refluxed at 55 ºC for 2 h and
cooled to r.t. A solution of HCl 1N was slowly added till pH 2 after which CH2Cl2 was
added and the mixture was washed with brine. The organic phase was dried with
Na2SO4, filtered, and solvent was removed under reduced pressure. The residue was
purified by flash chromatography giving compound 4 in 55% yield (0.17 g).
• From Fmoc Cysteine-OtBu (5). Compound 4 (0.11 g; 0.18 mmol) was dissolved in 6
mL CH2Cl2 after which 2 mL of TFA were slowly added at r.t. The mixture was
stirred overnight at r.t. and then toluene was added and the solvent was removed under
S5

reduced pressure. The residue was coevaporated two times more with toluene to obtain
4 (0.1 g, quant.).
• From Fmoc-Cysteine(Trt)-OH. Fmoc-cysteine(Trt)-OH (4 g; 6.8 mmol) was
deprotected following reported conditions.2 The residue was dissolved in 30 mL DCE
and the radical alkylation was performed under the general conditions described,
yielding 4 (2.0 g, 53%) after purification by column chromatography using
1
CH2Cl2:MeOH (95:5). Analytical data: H-NMR (400 MHz, CDCl3): 0.87 (t, 3H, J=
6.8 Hz), 1.24 (s, 26H), 1.51 (m, 2H), 2.52 (m, 2H), 3.02 (m, 2H), 4.20 (t, 1H, J= 6.8
Hz), 4.38 (s, 2H), 4.37 (s, 1H), 5.76 (bs, 1H), 7.27 (t, 2H, J= 7.2 Hz), 7.36 (t, 2H, J=
13
7.3 Hz), 7.55 (s, 2H), 7.73 (d, 2H, J= 7.59 Hz); C-NMR (100 MHz, CDCl3): 14.0,
22.6, 28.7, 29.1, 29.2, 29.47, 29.49, 29.55, 29.59, 29.60, 29.63, 31.8, 32.8, 34.1, 47.0,
20
53,4, 67.3, 119.9, 125.0, 127.0, 127.6, 130.3, 141.2, 143.5, 143.7, 155.8, 175.0; [α]D
32
-8.9 (c 0.22, CH2Cl2); LC-MS (ESI): calcd for C34H50NO4 S: 568.35 [M+H] +, found
568.23 [M+H] +, Rt 9.76 min; calcd for C34H50O4N1 S1: 568.3455 [M+H] +, 590.3275
32
[M+Na] +, found: 568.3451 [M+H] +, 590.3270 [M+Na] +.
O
H
N
Fmoc
OH
(CH2)6CH3
S
(L)-2-(9H-Fluoren-9-ylmethoxycarbonylamino)-3-octylsulfanyl-propionic acid (6) (Table
2, entry 1). After deprotection of Fmoc-cysteine(Trt)-OH (1.33 g; 2.28 mmol) under acidic
conditions, the radical reaction was performed in DCE with 1-octene (1.16 mL; 6.8 mmol)
under the general conditions described. After purification by column chromatography using
CH2Cl2:MeOH (95:5), compound 6 was isolated as a white foam (0.59 g; 57%). Analytical
data: 1H-NMR (400 MHz, CD3OD): 0.86 (t, 3H, J= 6.8 Hz), 1.2-1.4 (m, 8H), 1.37 (t, 2H, J=
6.8 Hz), 1.58 (q, 2H, J= 7.6 Hz), 2.56 (t, 2H, J= 7.2 Hz), 2.84 (dd, 1H, J= 8.4, 13.6 Hz) , 2.87
(dd, 1H J= 3.6, 14 Hz), 4.24 (q, 1H, J= 6.8 Hz), 4.33 (m, 2H), 4.38 (dd, 1H, J= 6.8, 10.4 Hz),
7.30 (dt, 2H, J= 1.2, 7.6 Hz), 7.38 (t, 2H, J= 7.2 Hz), 7.69 (d, 2H J= 7.6 Hz), 7.78 (d, 2H, J=
7.6 Hz); 13C-NMR (100 MHz, CDCl3): 14.0, 22.6, 28.8, 29.1, 29.5, 31.7, 32.8, 47.0, 53.9,
20
67.4, 119.9, 125.13, 127.0, 127.6, 143.6, 156.2, 175.9; [α]D -5.6 (c 1, CH2Cl2); LC-MS
32
(ESI): calcd for C26H34O4N1 S1: 456.22 [M+H] +; found 456.16 [M+H] +, Rt 6.07 min; ES
32
MS: m/z: calcd for C26H34O4N1 S1: 456.22031 [M+H] +; found: 456.22003 [M+H] +.
S6

O
S
H
N
Fmoc
OH
(L)-2-(9H-Fluoren-9-ylmethoxycarbonylamino)-3-(2-methyl-hexylsulfanyl)-propionic
acid (7) (Table 2, entry 2). After deprotection of Fmoc-cysteine(Trt)-OH (1.33 g; 2.28
mmol) and radical alkylation using 2-methyl-1-hexene as alkene, compound 7 was isolated
after column chromatography using CH2Cl2:MeOH (95:5) (0.79 g; 91%). Analytical data: 1H-
NMR (400 MHz, CDCl3): 0.78 (t, 3H, J= 6.8 Hz), 0.86 (dd, 3H, J= 6.8 Hz), 1.1 (dd, 2H, J=
7.6, 17.2 Hz), 1.66 (m, 4H), 1.52 (m, 1H), 2.29 (m, 1H), 2.34 (m, 1H), 2.93 (bs, 2H), 4.14 (t,
1H, J= 7.2 Hz), 4.29 (d, 2H, J= 7.2 Hz), 4.43 (m, 1H), 5.67 (d, NH, J= 7.6 Hz), 7.16 (t, 2H,
J= 7.6 Hz), 7.22 (t, 2H, J= 7.2 Hz), 7.31 (d, 2H, J= 7,6 Hz ), 7.52 (d, 2H, J= 7.6 Hz), 8.51
13
(bs, 1H); C-NMR (100 MHz, CDCl3): 14.0, 19.1, 19.2, 22.7, 27.1, 29.0, 29.1, 33.2, 33.28,
34.7, 34.8, 35.6, 35.7, 40.5, 40.6, 47.0, 57.6, 67.3, 119.9, 120.2, 124.9, 127.0, 127.6, 141.2,
32
143.6. 156.0, 175.2; [α]D20 +4.6 (c 0.11, CH2Cl2); LC-MS (ESI): calcd for C25H32O4N1 S1:
32
442.21 [M+H] +; found 442.11 [M+H] +, Rt 5.44 min; ES MS: m/z: calcd for C25H32O4N1 S1:
442.20466 [M+H] +; found: 442.20443 [M+H] +.
O
S
O
S
H
N
H
N
Fmoc
OH
Fmoc
OH
(9H-Fluoren-9-ylmethoxycarbonylamino)-3-(1-methyl-heptylsulfanyl)-propionic
acid,
acid
(9H-Fluoren-9-ylmethoxycarbonylamino)-3-(1-ethyl-hexylsulfanyl)-propionic
(8a/8b) (Table 2, entry 3). After deprotection Fmoc-cysteine(Trt)-OH (1.33 g, 2.28 mmol)
and radical alkylation using trans-2-octene as alkene, compound 8 was isolated after column
chromatography in silica gel using CH2Cl2:MeOH (95:5) (0.3 g, 28%) as a mixture of
1
regioisomers (3.3:1). Analytical data: H-NMR (400 MHz, CD3OD): 0.82 (m, 3H), 0.98 (dt,
3H, J= 3.2, 7.2 Hz), 1.09 (d, 3H, J= 6.8 Hz), 1.12 (d, 3H, J= 6.4 Hz), 1.24 (m, 8H), 1.57 (m,
1H), 2.62 (q, 1H, J= 4.8 Hz), 2.83 (m, 1H), 3.00 (m, 1H), 4.23 (q, 1H, J= 6.4 Hz), 4.33 (m,
3H), 7.04 (t, 2H, J= 7.2 Hz), 7.13 (t, 2H, J= 7.2Hz), 7.36 (dd, 2H, J= 7.2 Hz), 7.49 (d, 2H,
13
J= 7.2 Hz); C-NMR (100 MHz, CDCl3:CD3OD): 13.3, 18.3, 22.0, 25.9, 25.97, 26.0, 28.7,
28.8, 29.1, 31.2, 31.3, 33.4, 36.6, 36.63, 37.4, 39.2, 40.3, 40.4, 41.1, 42.0, 46.6, 65.6, 119.4,
20
124.63, 126.6, 127.0, 129.0, 140.8, 143.3, 155.8, 167.4, 172.5; [α]D -10.21 (c 0.95, CH2Cl2);
S7

32
+
+
LC-MS (ESI): calcd for C26H34NO4 S: 456.22 [M+H] ; found 456.07 [M+H] , Rt 10.41
32
min; ES MS: m/z: calcd for C26H34NO4 S: 456.2203[M+H]+, 478.2023 [M+Na]+; found:
456.2200 [M+H] +, 478.2018 [M+Na]+.
O
O
O
S
N
H
N
O
6-(5-Dimethylamino-naphtalene-1-sulfonylamino-hexanoic acid allyl ester (9). O-Allyl
aminocaproic ester p-TsOH salt (0.40 g; 1.18 mmol) and DIPEA (1 mL; 5.93 mmol) were
dissolved in 10 mL CH2Cl2 and a solution of dansyl chloride (0.32 g, 1.18 mmol) in CH2Cl2
(5 mL) was slowly added. The mixture was stirred at r.t. for 20 h, the solvent was removed
under reduced pressure and the residue was purified by flash chromatography in silica gel
using a mixture of CH2Cl2:MeOH 99.6:0.4 as eluent. Compound 9 (0.33 g; 70%) was
isolated. Analytical data: 1H-NMR (400 MHz, CDCl3): 1.15 (m, 2H), 1.36 (q, 2H, J= 7.2 Hz),
1.40 (q, 2H, J= 7.2 Hz), 2.14 (t, 2H, J= 7.6 Hz), 2.87 (s, 6H), 2.87 (q, 2H, J= 6.8 Hz), 4.52
(td, 2H, J=1.4, 5.7 Hz), 4.94 (t, 1H, J= 6.1 Hz), 5.23 (qdd, 2H, J= 1.4, 10.4, 23.8 Hz), 5.87
(tdd, 1H, J= 5.7, 10.4, 17.2, Hz), 7.52 (ddd, 2H, J= 7.4, 13.2 Hz), 8.23 (dd, J= 1.2, 7.3 Hz),
8.30 (d, 1H, J= 8.6 Hz), 8.53 (d, 1H, J= 8,8 Hz); 13C-NMR (100 MHz, CDCl3): 24.0, 5.7,
29.0, 33.7, 42.9, 45.3, 64.9, 115.1, 118.0, 118.7, 123.1, 128.2, 129.5, 129.55, 129.8, 130.3,
32
+
132.1, 134.7, 151.9, 173. LC-MS (ESI): calcd for C21H29N2O4 S: 405.18 [M+H] ; found
32
405.17 [M+H] +, Rt 4.01 min; ES MS: m/z: calcd for C21H29N2O4 S: 405.18426 [M+H] +;
found: 405.18381 [M+H] +.
O
H
N
Fmoc
OH
O
O
S
O
S
N
H
N
O
2-(((9H-fluoren-9-yl)methoxy)carbonylamino)-3-(3-(6-(5-(dimethylamino)naphthalene-
1-sulfonamido) hexanoyloxy)propylthio)propanoic acid (10) (Table 2, entry 4). After
deprotection of Fmoc-cysteine(Trt)-OH under acidic conditions (0.35 mmol), alkene 9 (0.14
g; 0.34 mmol) and AIBN (28 mg; 0.17 mmol) were added to the solution. Radical alkylation
was performed under the general conditions using 1 equivalent of alkene and compound 10
was purified by column chromatography using CH2Cl2:MeOH (95:5) as eluent (90 mg, 35%).
S8

Analytical data:1H-NMR (400 MHz, CDCl3): 1.17 (t, 2H, J= 8 Hz), 1.34 (t, 2H, J= 7.2 Hz),
1.43 (t, 2H, J= 7.6 Hz), 1.84 (m, 2H), 2.11 (t, 2H, J= 7.2 Hz), 2.58 (m, 2H), 2.86 (m, 8H),
3.05 (m, 2H), 4.08 (t, 2H, J= 6.8 Hz), 4.18 (t, 1H, J= 7.2 Hz), 4.36 (t, 2H, J= 9.2 Hz), 4.57
(bs, 1H), 5.22 (bs, 1H), 5.90 (bs, 1H), 7.17 (d, 1H, J= 8 Hz), 7.26 (t, 2H, J= 7.6 Hz), 7.35 (2H,
J= 7.2 Hz), 7.50 (m, 2H), 7.56 (t, 2H, J= 6.8 Hz), 7.77 (d, 2H J= 7.6 Hz), 7.73 (d, 2H, J= 7.6
13
Hz), 8.21 (dd, 1H, J= 0.8, 7.2 Hz), 8.30 (d, 1H, J= 8.8 Hz), 8.52 (d, 1H, J= 8.8 Hz); C-
NMR (100 MHz, CD3OD): 24.3, 26.0, 28.7, 20.3, 34.0, 42.9, 45.5, 47.32, 47.39, 63.1, 67.3,
115.4, 119.1, 120.1, 123.4, 125.3, 127.2, 127.3, 127.9, 128.3, 129.5, 129.8, 130.4, 141.4,
20
144.0, 152.0, 171.2, 174.2. [α]D
+5.83 (c 0.24, CH2Cl2); LC-MS (ESI): calcd for
32
C39H46O8N3 S2 748.27 [M+H] +; found 748.22 [M+H] +, Rt 13.51 min; ES MS: m/z: calcd
32
for C39H46O8N3 S2: 748.27209 [M+H] +; found: 748.27207 [M+H] +.
O
H
N
Fmoc
OH
S
O
O
O
S
NH
O
O
O
HN
O
2-(((9H-fluoren-9-yl)methoxy)carbonylamino)-21-oxo-25-(2-oxohexahydro-1H-
thieno[3,4-d]imidazol-4-yl)-8,11,14,17,20-pentaoxa-4-thiapentacosan-1-oic acid (12)
(Table 2, entry 5). After deprotection of Fmoc-cysteine(Trt)-OH under acidic conditions (30
mg, 0.05 mmol), radical alkytion was performed using equimolar conditions of alkene 11 (22
mg, 0.05 mmol) and AIBN (4 mg, 0,02 mmol) in 1 mL DCE. After purification by flash
chromatography using CH2Cl2:MeOH (95:5), compound 12 was isolated (16 mg; 0,020
1
mmol) 42%. Analytical data: H-NMR (500 MHz, CDCl3;CD3OD,): 1.18 (qn, 2H, J= 8 Hz,
2H), 1.41 (m, 4H), 1.60 (qn, 2H, J= 6.5 Hz, 2H), 2.13 (t, 2H, J= 7.5 Hz), 2.40 (m, 2H), 2.50
(d, 1H, J= 13 Hz), 2.67 (dd, 1H, J= 5, 13 Hz), 2.73 (dd, 1H, J= 6.5, 13 Hz), 2.83 (dd, 1H, J=
4.5, 14 Hz), 2.92 (m, 1H), 3.30 (t , 2H, J= 6 Hz), 3.33-3.42 (m, 12H), 3.54 (t, 2H, J= 4.5 Hz),
3.97 (t, 2H, J= 5 Hz), 3.97 (t, 1H, J= 7 Hz), 4.06 (dd, 1H, J= 4.5, 8 Hz), 4.12-4.30 (m, 4H),
7.07 (t, 2H J= 7 Hz), 7.15 (t, 2H J= 7.5 Hz), 7.40 (d, 2H, J= 7 Hz), 7.53 (d, 2H, J= 7.5 Hz);
20
32
+
[α]D +7.5 (c 0.12, CH2Cl2); LC-MS (ESI): calcd for C39H54O11N3 S2: 804.31 [M+H] ;
32
found 804.30 [M+H] +, Rt 2.23 min; ES MS: m/z:
calcd for C39H54O11N3 S2:
804.31942[M+H] +; found: 804.31985 [M+H] +.
References
(1)Swali, V.; Matteucci, M.; Elliot, R.; Bradley, M. Tetrahedron 2002, 58, 9101-9109.
(2)Lumbierres, M.; Palomo, J.; Kragol, G.; S., R.; Müller, O.; Waldmann, H. Chem. Eur. J. 2005, 11, 7405-7415.
S9

O
S
H
N
Fmoc
OCH3
(CH2)14CH3
3
7.0
6.0
5.0
4.0
3.0
2.0
1.0
ppm (t1)
S10

O
S
1500
1000
5000
0
H
N
Fmoc
OCH3
(CH2)14CH3
3
150
100
50
ppm (t1)
S11

O
S
H
N
Fmoc
OH
(CH2)14CH3
4
8.0
ppm (t1)
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
S12

O
S
H
N
Fmoc
OtBu
(CH2)14CH3
5
8.0
ppm (t1)
7.0
6.0
5.0
4.0
3.0
2.0
1.0
S13

O
S
H
N
Fmoc
OtBu
(CH2)14CH3
5
150
100
50
0
ppm (t1)
S14

O
S
H
N
Fmoc
OH
(CH2)6CH3
6
500
0
8.0
ppm (t1)
7.0
6.0
5.0
4.0
3.0
2.0
1.0
S15

O
S
H
N
Fmoc
OH
7
10.0
ppm (t1)
5.0
0.0
S16

O
S
O
S
H
N
H
N
Fmoc
OH
Fmoc
OH
1000
500
0
8a/8b
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
ppm (t1)
S17

O
O
O
S
N
H
N
O
9
5.0
0.0
ppm (t1)
S18

O
S
H
N
Fmoc
OH
O
O
O
S
N
H
N
O
10
9.0
ppm (t1)
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
S19

O
S
H
N
Fmoc
OH
S
O
O
O
NH
O
O
O
HN
O
12
8.0
ppm (t1)
7.0
6.0
5.0
4.0
3.0
2.0
1.0
S20