Katritzky et al.
JOCArticle
Fmoc-L-Met-S-L-Cys(NH3Cl)-OH (4b): white microcrystals;
yield 35%; mp 150-152 °C; H NMR (300 MHz, DMSO-d6)
δ 1.80-1.94 (m, 2H), 1.94-1.99 (m, 1H), 2.04 (s, 3H), 2.41-2.45
(m, 1H), 3.32-3.34 (m, 2H), 4.10-4.14 (m, 1H), 4.26, (t, J =
6.9 Hz, 1H), 4.38-4.39 (m, 3H), 7.34 (t, J = 6.9 Hz, 2H), 7.43
(t, J = 7.2 Hz, 2H), 7.73 (d, J = 6.3 Hz, 2H), 7.91 (d, J = 7.5 Hz,
2H), 8.18 (d, J = 7.5 Hz, 1H), 8.53 (br s, 3H); 13C NMR
(75 MHz, DMSO-d6) δ 14.5, 27.8, 29.5, 30.3, 46.7, 51.5, 59.9,
65.8, 120.1, 125.2, 127.1, 127.7, 140.7, 143.6, 143.7, 156.1, 169.0,
200.5. Anal. Calcd for C23H27ClN2O5S2: C, 54.05; H, 5.33; N,
5.48. Found: C, 54.05; H, 5.36; N, 5.44.
Z-L-Tyr-L-Cys-S-(Z-L-Leu)-OH (5d): white microcrystals;
yield 85%; mp 84-88 °C; 1H NMR (300 MHz, DMSO-d6)
δ 0.83-0.87 (m, 6H), 1.45-1.80 (m, 3H), 2.85-3.20 (m, 4H),
4.10-4.40 (m, 3H), 4.85-5.15 (m, 4H), 6.63 (d, J = 8.3 Hz, 2H),
7.07 (d, J = 8.3 Hz, 2H), 7.19-7.50 (m, 10H), 8.9 (d, J = 7.8 Hz,
1H), 8.41 (d, J = 8.1 Hz, 1H), 9.20 (s, 1H); 13C NMR (75 MHz,
DMSO-d6) δ 21.1, 21.3, 22.8, 22.9, 24.2, 29.4, 36.9, 51.6, 56.5,
59.7, 65.2, 65.8, 114.9, 127.4, 127.5,127.7, 127.8, 127.9, 128.3,
128.4, 130.2, 136.8, 137.1, 155.8, 156.2, 171.6, 171.9, 201.8. Anal.
Calcd for C34H39N3O9S: C, 61.34; H, 5.90; N, 6.31. Found: C,
61.66; H, 6.28; N, 5.95.
1
General Procedure for S-Acylations of Cysteine-Containing
Peptides with N-Acylbenzotriazoles and N-(Pg-r-aminoacyl)-
benzotriazoles To Give 5a-l. To a precooled solution of cysteine-
containing peptides in MeCN/H2O (7 mL:3 mL) at 10 °C was added
a solution of N-acylbenzotriazoles or N-(Pg-R-aminoacyl)benzo-
triazoles in MeCN with stirring followed by addition of KHCO3 for
10 min in four installments. After additional stirring for 20 min at
room temperature, the reaction mixture was acidified with 5 N HCl.
The solution was then extracted with ethyl acetate, washed with
water, and dried over sodium sulfate. Evaporation of the solvent
gave the desired product, which was recrystallized from chloroform-
hexanes or ethyl acetate-hexanes.
Z-L-Met-L-Cys-S-(Z-L-Met)-OH (5e): white microcrystals;
yield 90%; mp 146-150 °C; H NMR (300 MHz, DMSO-d6)
1
δ 1.75-2.00 (m, 3H), 2.01 (br s, 6H), 2.40-2.65 (br m, 5H),
3.07-3.15 (m, 1H), 3.21-3.35 (m, 1H), 4.10-4.20 (m, 1H),
4.25-4.45 (m, 2H), 5.01-5.15 (m, 4H), 7.35 (br s, 10H), 7.49
(d, J = 8.3 Hz, 1H), 8.13 (d, J = 7.8 Hz, 1H), 8.33 (d, J = 7.8 Hz,
1H); 13C NMR (75 MHz, DMSO-d6) δ 14.5, 14.7, 29.5, 29.6, 30.6,
31.8, 51.6, 53.8, 60.0, 65.5, 65.9, 127.8, 127.9, 128.4, 136.8, 137.0,
156.0, 156.2, 171.5, 171.6, 173.8, 201.2. Anal. Calcd for C29H37N3-
O8S3: C, 53.44; H, 5.72; N, 6.45. Found: C, 53.63; H, 5.82; N, 6.76.
Z-L-Trp-L-Cys-S-(PhCO)-OH (5f): pink microcrystals; yield
70%; mp 156-158 °C; 1H NMR (300 MHz, DMSO-d6) δ
2.97-2.89 (m, 1H), 3.19-3.13 (m, 2H), 3.67 (dd, J = 13.1,5
Hz, 1H), 4.41-4.35 (m, 1H), 4.59-4.51 (m, 1H), 4.95 (s, 2H),
7.00 (t, J = 7.1 Hz, 1H), 7.1 (t, J = 7.4 Hz, 1H), 7.19-7.38
(m, 7H), 7.46 (d, J = 8.2 Hz, 1H), 7.76-7.56 (m, 4H), 7.96
(d, J = 7.1 Hz, 1H), 8.56 (d, J = 7.6 Hz, 1H), 10.86 (br s, 1H),
13.05 (br s, 1H); 13C NMR (75 MHz, DMSO-d6) δ 27.8,
29.9,51.6, 55.4, 65.2, 110.1, 111.3, 118.2, 118.5, 120.9, 123.9,
126.9, 127.2, 127.4, 127.7, 128.3, 129.1, 134.1, 136.1, 136.2,
136.9, 155.8, 171.6, 172.1, 190.6. Anal. Calcd for C29H27N3O6S:
C, 63.84; H, 4.99; N, 7.70. Found: C, 63.58; H, 5.19; N, 7.54.
Fmoc-L-Phe-L-Cys-S-(p-toluoyl)-OH (5g): white microcrys-
tals; yield 78%; 152-154 °C; 1H NMR (300 MHz, DMSO-d6)
δ 2.34 (s, 3H), 2.79 (t, J = 12.6 Hz, 1H), 3.05 (dd, J = 13.2,
3.0 Hz, 1H), 3.29-3.37 (m, 1H), 3.62 (dd, J = 4.8, 13.5 Hz, 1H),
4.07-4.14 (m, 3H), 4.28-4.38 (m, 1H), 4.48-4.53 (m, 1H), 7.19
(d, J = 6.9 Hz, 1H), 7.23-7.32 (m, 9H), 7.40 (t, J = 7.5 Hz, 2H),
7.62 (t, J = 6.0 Hz, 2H), 7.68 (d, J = 8.7 Hz, 1H), 7.79 (d, J =
7.8 Hz, 2H), 7.88 (d, J = 7.2 Hz, 2H), 8.54 (d, J = 8.1 Hz, 1H);
13C NMR (75 MHz, DMSO-d6) δ 21.2, 29.3, 37.4, 38.8, 46.6,
51.7, 56.1, 65.8, 120.1, 125.3, 125.4, 126.3, 126.7, 127.0, 127.1,
127.7, 128.1, 129.3, 129.6, 133.7, 138.2, 140.7, 143.7, 143.8,
144.6, 155.8, 171.5, 171.8, 190.0. Anal. Calcd for C35H32N2O6S:
C, 69.06; H, 5.30; N, 4.60. Found: C, 68.70; H, 4.92; N, 4.75.
Fmoc-Phe-L-Cys-S-(Fmoc-L-Phe)-OH (5h): white microcrys-
tals; yield 47%; mp 171-173 °C; 1H NMR (300 MHz, DMSO-
d6) δ 2.72-2.90 (m, 2H), 3.02-3.19 (m, 4H), 4.06-4.21 (m, 6H),
4.27-4.44 (m, 3H), 7.16-7.41 (m, 18H), 7.56-7.64 (m, 5H),
7.87 (d, J = 7.4 Hz, 4H), 8.23 (d, J = 8.2 Hz, 1H), 8.53 (d, J =
7.7 Hz, 1H), 13.03 (br s, 1H); 13C NMR (75 MHz, DMSO-d6) δ
29.6, 37.3, 37.5, 46.5, 51.5, 56.0, 59.8, 62.7, 65.7, 65.8, 120.1,
125.3, 125.4, 126.3, 127.1, 127.6, 128.0, 128.2, 129.1, 129.3, 137.4,
138.1, 140.6, 140.7, 143.6, 143.7, 143.8, 155.8, 155.8, 171.6, 171.8,
200.6; HRMS (ESI) calcd for C51H45N3O8S [M þ Na]þ 882.2820,
found 882.2820.
Z-L-Trp-L-Cys-S-(Z-L-Trp)-OH (5a): white microcrystals;
1
yield 88%; mp 73-76 °C; H NMR (300 MHz, DMSO-d6) δ
2.85-3.01 (m, 3H), 3.12-3.21 (m, 4H), 4.30- 4.50 (m, 3H), 4.89
(s, 2H), 4.96 (s, 2H), 6.96 (t, J = 8.7 Hz, 3H), 7.06 (t, J = 7.5 Hz,
3H), 7.16-7.21 (m, 6H), 7.27-7.41 (m, 8H), 7.52 (d, J = 9.7 Hz,
1H), 7.66 (d, J = 7.7 Hz, 1H), 8.15 (d, J = 7.1 Hz, 1H), 8.50
(d, J = 7.6 Hz, 1H), 10.83 (d, J = 12.6 Hz, 2H); 13C NMR
(75 MHz, DMSO-d6) δ 20.0, 27.9, 29.6, 51.6, 55.5, 62.2, 65.2,
65.6, 109.6, 110.2, 111.3, 111.5, 118.0, 118.2, 118.5, 120.8, 121.0,
123.9, 126.9, 127.3, 127.4, 127.6, 127.7, 128.3, 128.4, 136.1, 136.7,
136.9, 155.8, 156.0, 171.6, 172.1, 201.0; HRMS (ESI) calcd for
C41H39N5O8S [M þ Na]þ 784.2412, found 784.2431.
Z-L-Trp-L-Cys-S-(Z-L-Ala)-OH (5b): white microcrystals;
1
yield 90%; mp 63-66 °C; H NMR (300 MHz, DMSO-d6) δ
1.27(s, 3H), 2.86-3.36 (m, 4H), 4.15-4.50 (m, 3H), 4.80-5.15
(m, 4H), 6.97-7.45 (m, 15H), 7.67 (d, J = 8.2 Hz, 1H), 7.91 (br s,
1H), 8.12 (d, J = 8.3 Hz, 1H), 8.48 (d, J = 7.2 Hz, 1H), 10.8
(s, 1H); 13C NMR (75 MHz, DMSO-d6) δ 14.1, 17.3, 22.1, 27.9,
29.4, 31.1, 51.6, 55.5, 56.7, 65.3, 65.8, 110.2, 111.4, 118.2, 118.6,
120.9, 124.0, 127.3, 127.5, 127.7, 127.9, 128. 3, 136.1, 136.7,
137.0, 155.8, 155.9, 171.6, 172.1, 201.9; HRMS (ESI) calcd for
C33H34N4O8S [M þ H2O þ 2H]þ 666.2359, found 666.2465.
Z-L-Ala-L-Cys-S-(Z-L-Trp)-OH (5c): white microcrystals;
yield 90%; mp 65-67 °C; 1H NMR (300 MHz, DMSO-d6)
δ 1.15-1.30 (m, 4H), 1.99 (s, 1H), 2.85-3.05 (m, 2H), 3.06-3.25
(m, 3H), 3.95-4.19 (m, 1H), 4.38 (br s, 1H), 4.85-5.15 (m, 4H),
7.00 (d, J = 7.5 Hz, 1H), 7.08 (t, J = 7.2 Hz, 1H), 7.17 (s, 1H),
7.25 (s, 1H), 7.33 (br s, 8H), 7.46 (d, J = 6.9 Hz, 1H), 7.54 (d, J =
7.2 Hz, 1H), 8.15 (d, J = 7.8 Hz, 1H), 8.29 (d, J = 7.2 Hz, 1H),
10.88 (s, 1H); 13C NMR (75 MHz, DMSO-d6) δ 18.4, 27.2, 29.7,
50.1, 51.7, 62.3, 65.6, 109.7, 111.7, 118.1, 118.7, 121.2, 124.1,
127.1, 127.5, 127.9, 128.5, 136.3, 136.9, 137.0, 155.8, 156.2,
171.7, 172.8, 201.0; HRMS (ESI) calcd for C33H34N4O8S
[M þNa]þ 669.1995, found 669.1995.
Z-DL-Ala-L-Cys-S-(Z-L-Trp)-OH (5cþ5c0): white microcrys-
tals; yield 90%; 1H NMR (300 MHz, DMSO-d6) δ 0.86 (s, 1H),
1.23 (s, 4 H), 2.96 (br s, 1H), 3.03-3.30 (m, 3H), 4.10 (br s, 1H),
4.37 (br s, 2H), 4.99 (d, J = 8.1 Hz, 3H), 7.00 (d, J = 6.9 Hz, 1H),
7.08 (br s, 1H), 7.17 (s, 1H), 7.19-7.42 (m, 10H), 7.48 (t, J =
7.8 Hz, 2H), 8.15 (d, J = 7.2 Hz, 1H), 8.22-8.42 (m, 1H) 10.89 (s,
1H), 13.02 (s, 1H); 13C NMR (75 MHz, DMSO-d6) δ 18.45, 18.63,
27.2, 30.1, 50.2, 51.5, 62.3, 65.7, 65.8, 109.7, 111.7, 118.1, 118.7,
121.3, 124.1, 127.1, 127.6, 127.9, 128.6, 129.4, 136.3, 136.9, 137.1,
155.8, 156.2, 171.7, 172.8, 201.0 Anal. Calcd for C33H34N4O8S: C,
61.29; H, 5.30; N, 8.66. Found: C, 61.04; H, 5.70; N, 9.15.
Fmoc-L-Met-L-Cys-S-(Z-L-Leu)-OH (5i): white microcrys-
tals; yield 83%; mp 84-86 °C; 1H NMR (300 MHz, DMSO-d6)
δ 0.81-0.86 (m, 6H), 1.24 (br s, 1H), 1.47-1.62 (m, 2H),
1.83-1.93(m, 2H), 2.04 (s, 3H), 2.45-2.48 (m, 1H), 3.05-3.13
(m, 3H), 3.26-3.42 (m, 1H), 4.15-4.31 (m, 5H), 5.07 (s, 2H),
7.30-7.35 (m, 5H), 7.42 (t, J = 7.5 Hz, 2H), 7.59 (d, J =
8.1 Hz, 1H), 7.72 (t, J = 6.9 Hz, 2H), 7.89 (d, J = 7.2 Hz, 2H),
8.07 (d, J = 7.5 Hz, 1H), 8.33 (d, J = 7.5 Hz, 1H); 13C NMR
(75 MHz, DMSO-d6) δ 14.6, 20.9, 22.8, 24.2, 29.3, 29.6, 31.9,
46.7, 51.5, 53.7, 59.6, 65.7, 120.1, 125.3, 127.0, 127.6, 127.8,
128.3, 136.8, 140.7, 143.7, 143.9, 155.8, 156.1, 171.4, 171.5,
94 J. Org. Chem. Vol. 76, No. 1, 2011