8040 Journal of Medicinal Chemistry, 2005, Vol. 48, No. 25
Li et al.
3.1H), 4.85-4.33 (m, 3.5H), 4.02-3.73 (m, 1.8H), 3.64-2.88
(m, 10.6H), 2.88-2.05 (m, 20.9H), 2.05-1.53 (m, 1.7H), 1.53-
0.52 (m, 23.7H); 13C NMR (CDCl3) δ 173.63, 173.36, 171.15,
170.52, 169.71, 169.44, 156.76, 156.39, 156.06, 155.84, 155.55,
155.32, 155.18, 155.10, 138.99, 138.89, 138.80, 138.55, 133.80,
133.54, 133.50, 133.27, 131.66, 131.44, 131.06, 130.92 (26q),
128.54, 128.30, 127.99, 127.50, 127.07, 126.71, 126.64, 126.17,
125.91, 125.62 (10t), 124.24, 123.99, 123.55, 122.96 (4q),
116.14, 116.05, 115.78, 115.53 (4t), 8.057, 80.45, 80.12, 80.04
(4q), 55.96, 53.80, 50.84, 49.36 (4t), 45.61, 44.68, 38.83, 38.00,
37.21, 33.46, 32.12, 31.52, 30.85, 30.49, 28.96, 28.79 (12s),
28.36, 28.35 (2p), 28.05, 27.04, 24.07, 23.84 (4s), 20.42, 20.39,
19.99, 19.92, 17.84 (5p).
3-(Boc-Dmt-Tic-NH-butyl)-6-(Boc-Dmt-Tic-NH-propyl)-
2(1H)-pyrazinone (6). Starting from 3-[Z-NH-(CH2)4]-6-[Z-
NH-(CH2)3]-2(1H)-pyrazinone (136 mg, 0.27 mmol), the crude
compound was purified with silica gel chromatography (2.6
cm × 34 cm; AcOEt:MeOH ) 20:1): yield 145 mg (47%); mp
164-165 °C; Rf2 ) 0.57; [R]25D -4.0° (c ) 0.33, MeOH); 1H NMR
(400 MHz, CDCl3) δ 8.80 (br, 1H), 7.95-7.32 (m, 1H), 7.18-
6.73 (m, 8H), 6.70-6.40 (m, 4H), 5.64-5.33 (m, 1.8H), 5.33-
4.85 (m, 3.1H), 4.85-4.25 (m, 3.2H), 4.00-3.70 (m, 1.6H),
3.45-2.72 (m, 10.5H), 2.70-1.77 (m, 21.4H), 1.60-0.80 (m,
25H); 13C NMR (CDCl3) δ 173.92, 173.28, 171.13, 170.96,
170.06, 169.91, 156.55, 156.33, 156.23, 155.90, 155.82, 177.71,
155.49, 155.26, 155.15, 138.99, 138.75, 138.64, 133.69, 133.66,
133.48, 133.02, 131.63, 131.28 (24q), 128.41, 128.35, 128.23,
127.71, 127.40, 126.94, 126.82, 126.38, 126.23, 125.90 (10t),
124.09, 122.94 (2q), 115.86, 115.70 (2t), 80.70, 80.39, 80.19,
80.05 (4q), 55.93, 54.54, 54.13, 50.85, 50.43, 49.50 (6t), 45.75,
44.66, 44.10, 38.96, 38.20, 37.93, 33.50, 32.00, 31.45, 30.57,
30.12, 28.70 (12s), 28.37, 28.32 (2p), 26.41, 25.55, 23.72, 23.58
(4s), 20.43, 20.35, 20.17, 19.97, 17.90 (5p).
3-(Boc-Dmt-Tic-NH-ethyl)-6-(Boc-Dmt-Tic-NH-butyl)-
2(1H)-pyrazinone (7). Starting from 3-[Z-NH-(CH2)2]-6-[Z-
NH-(CH2)4]-2(1H)-pyrazinone (130 mg, 0.26 mmol), the crude
compound was purified with silica gel chromatography (3.2
cm × 30 cm; CHCl3:MeOH ) 20:1): yield 185 mg (62%); mp
172-174 °C; Rf3 ) 0.57; [R]25D -6.0° (c ) 0.36, MeOH); 1H NMR
(400 MHz, CDCl3) δ 7.92-7.36 (m, 0.5H), 713-6.40 (m, 12H),
5.66-5.40 (m, 1.7H), 5.26-4.97 (m, 3.3H), 4.77-4.20 (m, 3.3H),
3.94-3.60 (m, 2.5H), 3.50-2.58 (m, 11.4H), 2.50-1.78 (m,
19.8H), 1.51-0.67 (m, 22.5H); 13C NMR (CDCl3) δ 173.95,
173.29, 171.16, 170.33, 170.06, 169.93, 157.07, 156.41, 155.93,
155.84, 155.70, 155.52, 155.20, 155.13, 152.13, 151.88, 138.98,
138.85, 138.76, 138.57, 133.79, 133.67, 133.64, 133.14, 131.61,
131.23, 131.17, 131.14 (28q), 128.43, 127.99, 127.81, 127.42,
127.07, 126.99, 126.95, 126.72, 126.65, 126.09, 125.88, 125.63
(12q), 124.30, 124.00, 122.98 (3q), 116.22, 116.07, 115.61,
115.50 (4t), 80.43, 80.25, 80.11, 80.05 (4q), 55.92, 54.59, 50.68,
49.36 (4t), 45.74, 44.52, 37.91, 37.36, 36.84, 33.33, 32.27, 31.70,
31.36, 30.41, 28.92 (11s), 28.37, 28.34 (2p), 28.17, 24.19 (2s),
20.37, 20.30, 20.03, 19.91, 17.97, 17.79 (6p).
General Procedure for Synthesis of Compound 8-14.
3,6-Bis(Boc-Dmt-Tic-NH-alkyl)-2(1H)-pyrazinones (compounds
1-7, 0.12 mmol) were treated with TFA (0.8 mL, 10 mmol)
and anisole (40 µL) for 1 h at room temperature. The reaction
solution was diluted with hexane, the solid was collected by
filtration, dried over KOH pellets, and purified by semi-
preparative RP-HPLC. The purified peptide was lyophilized
from water containing 1 mol/L HCl (250 µL) three times to
give an amorphous powder.
Dmt), 54.96, 54.89, 52.55, 51.62 (4t, R-C of Tic), 47.81, 47.69,
48.82, 48.43 (4t, R-C of Dmt), 43.24, 42.70 (2s, 1-C of Tic),
39.81, 39.40 (2s, NHCH2), 31.06, 30.38 (2s, â-C of Dmt), 28.99,
28.37 (2s, â-C of Tic), 20.02, 19.98, 19.51 (3p, CH3 of Dmt),
17.94 (p, 5-CH3 of pyrazinone).
3,6-Bis(Dmt-Tic-NH-ethyl)-2(1H)-pyrazinone‚2HCl
(9): yield 97 mg (77%); mp 226-228 °C; Rf5 ) 0.16; Rf6 ) 0.74;
tR ) 14.46 min; [R]25D +10.04° (c ) 0.48, H2O); m/z 898 (MH+);
1H NMR (400 MHz, DMSO-d6) δ 8.95-8.37 (m, 6H), 8.27 (br,
0.8H), 8.08 (br, 0.8H), 7.86 (br, 0.2H), 7.55 (br, 0.2H), 7.20-
6.73 (m, 8H), 6.54-6.22 (m, 4H), 5.08-4.95 (m, 0.4H), 4.86-
4.72 (m, 1.6H), 4.60-4.10 (m, 4H), 3.93-3.80 (m, 1.6H), 3.55-
3.45 (m, 0.4H), 3.34-2.85 (m, 9.3H), 2.85-2.35 (m, 5H), 2.35-
1.80 (m, 14.7H), 1.54-1.36 (m, 1.5H); 13C NMR (DMSO-d6) δ
169.09, 169.06, 168.30, 168.13, 156.04, 138.47, 138.39, 132.06,
131.88, 131.40, 131.35 (11q), 127.76, 126.39, 126.05, 125.99,
125.92, 125.43 (6t, aryl C of Tic), 121.39, 121.06, 120.98 (3q),
115.06 (t, aryl C of Dmt), 55.09, 54.99, 52.20 (3t, R-C of Tic),
48.80, 47.83 (2t, R-C of Dmt), 43.21, 43.07 (2s, 1-C of Tic),
37.66, 37.37 (2s, NHCH2CH2), 31.09 (s, NHCH2CH2), 31.00,
30.45 (2s, â-C of Dmt), 29.15, 28.97 (2s, â-C of Tic), 20.02,
19.58, 19.54, 19.49 (4p, CH3 of Dmt), 17.18 (p, 5-CH3 of
pyrazinone).
3,6-Bis(Dmt-Tic-NH-propyl)-2(1H)-pyrazinone‚2HCl
(10): yield 81 mg (74%); mp 222-223 °C; Rf5 ) 0.16; Rf6
)
0.75; tR ) 14.89 min; [R]25 +22.07° (c ) 0.42, H2O); m/z 926
D
(MH+); 1H NMR (DMSO-d6) δ 8.95-8.36 (m, 6H), 8.24 (br,
0.8H), 8.11 (br, 0.8H), 7.49 (br, 0.4H), 7.18-6.77 (m, 8H), 6.54-
6.25 (m, 4H), 5.05-4.95 (m, 0.4H), 4.82-4.66 (m, 1.6H), 4.57-
4.13 (m, 4H), 3.92-4.76 (m, 1.6H), 3.55 (dd, 0.4H, J ) 4.20,
15.16 Hz), 3.25-2.65 (m, 10.9H), 2.58-1.85 (m, 18.7H), 1.67-
1.27 (m, 5.5H); 13C NMR (DMSO-d6) δ 169.10, 169.01, 168.09,
167.97, 156.08, 156.04, 155.98, 155.57, 138.46, 138.38, 132.14,
132.10, 131.63, 131.48 (14q), 127.75, 127.67, 126.43, 126.08,
126.04, 125.99, 125.4 (7t, aryl C of Tic), 121.39, 121.03, 121.02
(3q), 115.10 (t, aryl C of Dmt), 55.03, 54.99, 52.70, 52.50 (4t,
R-C of Tic), 48.70, 48.01, 47.93 (3t, R-C of Dmt), 44.62, 43.41,
43.26 (3s, 1-C of Tic), 38.47, 38.28, 37.80 (3s, NHCH2(CH2)2),
31.06, 30.36 (2s, â-C of Dmt), 29.83, 29.46, 29.35 (3s, â-C of
Tic), 28.43 (s, NH(CH2)2CH2), 27.60 (s, NHCH2CH2CH2), 26.74
(s, NH(CH2)2CH2), 26.12 (s, NHCH2CH2CH2), 20.02, 19.51,
19.49 (3p, CH3 of Dmt), 17.26 (p, 5-CH3 of pyrazinone).
3,6-Bis(Dmt-Tic-NH-butyl)-2(1H)-pyrazinone‚2HCl
(11): yield 98 mg (85%); mp 219-220 °C; Rf5 ) 0.14; Rf6
)
0.74; tR ) 14.74 min; [R]25 +22.54° (c ) 0.42, H2O); m/z 954
D
1
(MH+); H NMR (400 MHz, DMSO-d6) δ 8.98-8.40 (m, 6H),
8.14 (s, 0.8H), 8.04 (s, 0.9H), 7.23-6.75 (m, 8.3H), 6.52-6.25
(m, 4H), 5.02 (t, 0.4H, J ) 4.56 Hz), 4.75-4.64 (m, 1.6H), 4.75-
4.64 (m, 0.8H), 4.57-4.40 (m, 0.8H), 4.38-4.24 (m, 1.6H),
3.85-3.75 (m, 1.6H), 3.54 (d, 0.4H, J ) 15.01 Hz), 3.26-2.85
(m, 9.2H), 2.78 (d, 1.6H, J ) 15.97 Hz), 2.62-2.45 (m, 1.2H),
2.43-1.95 (m, 17H), 1.67-0.97 (m, 10H); 13C NMR (DMSO-
d6) δ 169.10, 169.07, 168.98, 168.94, 167.85, 167.83, 156.09,
156.06, 155.98, 155.66, 138.43, 138.36, 138.43, 132.56, 132.37,
132.21, 132.15, 131.66, 131.53 (19q), 127.68, 126.66, 126.40,
126.35, 126.17, 126.08, 126.03, 125.98, 125.95, 125.45 (10t, aryl
C of Tic), 121.36, 121.03 (2q), 115.11 (t, aryl C of Dmt), 55.02,
52.70 (2t, R-C of Tic), 48.62, 48.07 (2t, R-C of Dmt), 44.71,
43.57, 43.52 (3s, 1-C of Tic), 38.41, 38.06 (2s, NHCH2CH2),
31.00, 30.76 (2s, â-C of Dmt), 29.66, 29.40 (2s, â-C of Tic), 28.77
(s, NH(CH2)3CH2), 28.55, 28.30 (2s, NHCH2CH2), 24.95, 23.55
(2s, NH(CH2)2CH2), 19.98, 19.50, 19.47 (3p, CH3 of Dmt), 17.06
(p, 5-CH3 of pyrazinone).
3-(Dmt-Tic-NH-propyl)-6-(Dmt-Tic-NH-butyl)-2(1H)-
pyrazinone‚2HCl (12): yield 105 mg (91%); mp 222-224 °C;
Rf5 ) 0.17; Rf6 ) 0.74; tR ) 15.01 min; [R]25D +24.05° (c ) 0.36,
H2O); m/z 940 (MH+); 1H NMR (400 MHz, DMSO-d6) δ 8.93-
8.35 (m, 6H), 8.18-7.97 (m, 1.6H), 7.49 (br, 0.2H), 7.19-6.75
(m, 8.2H), 6.52-6.25 (m, 4H), 4.96-4.87 (m, 0.4H), 4.72 (t,
1.6H, J ) 16.70 Hz), 4.58-4.10 (m, 4H), 3.87-3.73 (m, 1.6H),
3.55 (dd, 0.4H, J ) 7.73, 15.32 Hz), 3.38-2.84 (m, 9.2H), 2.79
(d, 1.7H, J ) 13.90 Hz), 2.60-1.88 (m, 18.6H), 1.58-1.47 (m,
3.5H), 1.37-0.94 (m, 4H); 13C NMR (DMSO-d6) δ 169.11,
169.08, 169.04, 168.97, 167.98, 167.83, 156.09, 156.04, 155.94,
3,6-Bis(Dmt-Tic-NH-methyl)-2(1H)-pyrazinone‚2HCl (8):
yield 95 mg (83%); mp 224-226 °C (dec); Rf5 ) 0.15; Rf6 ) 0.73;
tR ) 14.44 min; [R]25D +27.02° (c ) 0.35, H2O); m/z 870 (MH+);
1H NMR (400 MHz, DMSO-d6) δ 9.22 (br, 2H), 8.78 (s, 5H),
8.60-8.22 (m, 3.4H), 7.22-6.70 (m, 8.6H), 6.55-6.20 (m, 4H),
5.05-4.90 (m, 1H), 4.68-4.44 (m, 1.5H), 4.44-3.86 (m, 8.5H),
3.23-2.88 (m, 5H), 2.88-2.67 (m, 1.5H), 2.32-1.83 (m, 15H),
1.57-1.36 (m, 1.5H); 13C NMR (DMSO-d6) δ 169.04, 168.98,
168.40, 168.05, 156.07, 155.87, 154.13, 138.48, 138.44, 138.41,
138.30, 132.00, 131.88, 131.45, 131.24 (15q), 127.87, 127.74,
126.44, 126.29, 126.09, 125.99, 125.86, 125.60 (8t, aryl C of
Tic), 121.34, 121.25, 121.04, 120.99 (4q), 115.07 (t, aryl C of