Journal of Medicinal Chemistry
Article
DCM (2 × 40 mL). The combined organic extracts were dried over
triyl)triacetic Acid (15). Azido DOTAM 14 (30 mg, 0.02 mmol, 1.0
equiv) was dissolved in MeOH (800 μL) and DIPEA (200 μL) was
added at 0 °C. The ice bath was removed, the reaction was stirred for
4 h at 25 °C, and then the solvent was removed by rotary evaporation.
The residue was dried under high vacuum overnight to remove
residual DIPEA to yield a beige oil. A mixture of 1× PBS (pH 7.4)/
DMSO (300 μL each) and BCN-DOTA (20.14 mg, 0.03 mmol, 1.5
equiv) in 400 μL of MeOH were added. The reaction was stirred
overnight at 25 °C, and the reaction progress was controlled by
LCMS. After completion, the organic solvent was removed as much as
possible by rotary evaporation. The residual liquid was filtered and
injected into the RP-HPLC (C18 Phenomenex, 40 min gradient 0−
Na SO and concentrated in vacuo. The residue was dried under high
2
4
vacuum overnight, yielding 12 as a slightly yellow oil (773.36 mg, 2.29
mmol, 91%), which was used without further purification in the next
1
step. H NMR (500 MHz, CDCl ): δ 6.91 (br s, 1H), 3.87 (s, 2H),
3
1
3
3
.67 (m, 10 H), 3.59 (t, 2H), 3.49 (m, 2H), 3.39 (m, 2H) ppm.
C
NMR (100 MHz, CDCl ): δ 165.7, 70.9, 70.8, 70.6, 70.2, 69.5, 53.6,
3
+
5
0.8, 40.1, 29.3 ppm. ESI-HRMS: 12: C H BrN O calcd [M +
10 20 4 4
+
+
H] , 339.0662; measured [M + H] , 339.0663 (Δ = 0.1 ppm).
,2′,2″-(10-(14-Azido-2-oxo-6,9,12-trioxa-3-azatetradecyl)-
,4,7,10-tetraazacyclododecane-1,4,7-triyl)tris(N-(2-
aminoethyl)acetamide) (13). This compound was prepared
according to a modified literature procedure. Linker 12 (302 mg,
.89 mmol, 1.15 equiv) was dissolved in MeCN (2.5 mL) and added
2
1
33
30% MeCN/H O 0.1% HCOOH). Product-containing fractions were
2
0
identified by LCMS and lyophilized to dryness to yield 15 (30 mg,
to a stirred suspension of 9a (600 mg, 0.776 mmol, 1.0 equiv) and
1
0
.02 mmol, 80%) as a colorless oil. H NMR (700 MHz, DMSO-d ):
6
K CO (429 mg, 3.11 mmol, 4.0 equiv) in MeCN (7.5 mL). The
2
3
δ 13.12−12.19 (br s, 1H), 9.53−9.07 (s, 1H), 8.85 (d, J = 17.4 Hz,
reaction was continuously stirred overnight at 22 °C. The reaction
progress was monitored by LCMS, and after full conversion, the
reaction mixture was filtered and dried for 1 h in vacuo to obtain a
crude beige solid. The residue was dissolved in DCM (75 mL) and
washed with water and brine (each 2 × 50 mL) and then dried over
Na SO . The solvent was removed by rotary evaporation, and the
3
3
H), 8.19 (m, 6H), 7.69 (m, 1H), 7.43 (m, 1H), 7.26 (d, J = 8.0 Hz,
H), 6.92−6.89 (m, 3H), 6.65 (dd, J = 11.3, 4.5 Hz, 3H), 4.40−4.37
(
(
(
8
2
m, 2H), 4.05−3.99 (m, 2H), 3.79 (m, 2H), 3.72 (m, 2H), 3.56−3.51
m, 4H), 3.49 (m, 4H), 3.48−3.46 (m, 4H), 3.46−3.44 (m, 8H), 3.42
m, 6H), 3.39−3.37 (m, 8H), 3.34 (m, 4H), 3.30 (dd, J = 5.5 Hz,
2
4
H), 3.25 (dd, J = 10.1, 4.4 Hz, 4H), 3.16−3.14 (m, 2H), 3.11 (s,
H), 3.01−2.95 (m, 14H), 2.84 (br s, 8H), 2.76−2.72 (m, 2H), 2.67
residue was dried under high vacuum for 30 min. Then, DCM (5 mL)
and TFA (4 mL) were added at 0 °C, and the reaction was
equilibrated to room temperature and continuously stirred at 24 °C
for 3 h. After full conversion, the solvent was removed by rotary
evaporation, the residue was dried overnight under high vacuum, and
(
8
m, 4H), 2.12−2.05 (m, 2H), 1.56−1.50 (m, 2H), 1.09 (dd, J = 16.8,
13
.4 Hz, 1H), 0.91−0.89 (m, 1H) ppm. C NMR (176 MHz, DMSO-
d ): δ 181.3, 181.2, 179.4, 172.6, 165.9, 159.1, 155.7, 155.7, 152.7,
6
1
7
6
43.3, 128.3, 127.4, 126.7, 124.5, 124.5, 79.5, 79.2, 79.2, 79.1, 78.9,
8.8, 78.8, 78.7, 78.4, 78.4, 78.3, 70.9, 70.8, 65.7, 64.5, 64.3, 64.2,
0.5, 59.8, 59.5, 59.3, 56.7, 48.3, 48.2, 47.9, 47.6, 47.3, 34.8, 31.7,
crude 13 (229 mg, 0.313 mmol, 40% over two steps) was obtained as
1
a beige oil. H NMR (MeOH-d , 700 MHz): δ 4.57 (s, 4H), 3.68 (m,
4
8
3
H), 3.62 (m, 2H), 3.52 (t, J = 4.9 Hz, 2H), 3.41 (t, J = 5.5 Hz, 2H),
.16 (m, J = 6.4 Hz, 8H), 3.07 (t, J = 5.9 Hz, 8H), 3.06 (s, 4H), 2.92
31.4, 30.7, 28.6, 28.1, 26.8, 9.6 ppm. ESI-HRMS: 15:
2
+
2+
(
s, 4H), 2.15 (s, 4H), 2.08 (s, 4H) ppm.
C
80
H
122
N
20
O
25
calcd [M + 2H] , 881.4439; measured [M +
2
+
N,N′,N″-(((2,2′,2″-(10-(2-Oxo-14-(1l2,3l2-triaz-2-en-1-yl)-
2H] , 881.4325 (Δ = 1.4 ppm).
6
,9,12-trioxa-3-azatetradecyl)-1,4,7,10-tetraazacyclodode-
Gallium-2,2′,2″-(10-(2-oxo-2-((2-(((((5aR,6aS)-1-(2-oxo-1-
(4,7,10-tris(2-((2-(2,3-dihydroxybenzamido)ethyl)amino)-2-
oxoethyl)-1,4,7,10-tetraazacyclododecan-1-yl)-6,9,12-trioxa-
3 - a z a t e t r a d e c a n - 1 4 - y l ) - 1 , 4 , 5 , 5 a , 6 , 6 a , 7 , 8 -
octahydrocyclopropa[5,6]cycloocta[1,2-d][1,2,3]triazol 6yl)-
methoxy)carbonyl)amino)ethyl)amino)ethyl)-1,4,7,10-tetraa-
cane-1,4,7triyl)tris(acetyl))tris(azanediyl))tris(ethane-2,1-
diyl))tris(2,3-dihydroxybenzamide) (14). Oxalylchloride (250 μL,
2
1
.92 mmol, 9.0 equiv) was added to a stirred solution of 2 (386 mg,
.62 mg, 5.0 equiv) in dry DCM/DMF (500 μL/50 μL) at 0 °C
under Ar conditions. The suspension was stirred for 2 h at 22 °C, and
the reaction progress was checked by TLC. Subsequently, the solvent
was removed by rotary evaporation, and the residue was dried under
high vacuum overnight to yield a dark brown solid. 1,4-Dioxane (1.2
mL) was added, and the suspension was added dropwise to a solution
of 13 (237 mg, 0.32 μmol, 1.0 equiv) in 1 M K CO on ice. The pH
nat
zacyclododecane-1,4,7-triyl)triacetate ([ Ga]15). 15 (10 mg,
0
.006 mmol, 1.0 equiv) was dissolved in 200 μL of DMSO, and
nat
GaCl (2 mg, 0.011 mmol, 2 equiv), dissolved in NaOAc buffer, was
3
added at 23 °C. The reaction was heated to 100 °C under vigorous
stirring. The complexation progress was monitored by LCMSafter
full conversion (ca. 10 min), the solution was filtered and
subsequently injected into RP-HPLC (C18 Phenomenex, 40 min
2
3
was kept constant by addition of minute amounts of sat. K CO
2
3
solution when required. The reaction mixture was equilibrated to 23
C and continuously stirred for 1 h at that temperature. Subsequently,
°
gradient 2−30% MeCN/H O, 0.1% HCOOH). Product-containing
2
the mixture was extracted with DCM (3 × 100 mL), the combined
fractions were identified by LCMS and lyophilized to dryness, yielding
nat
organic extracts were dried over Na SO , and the solvent was
the complex [ Ga]15 as a white solid (7.9 mg, 0.004 mmol, 76%). H
2
4
removed in vacuo. The residue was taken up in MeCN/H O 1:1 (2.5
NMR (700 MHz, MeOH-d ): δ 7.34−7.07 (dd, J = 7.8, 1.3 Hz, 3H),
2
4
mL) and purified by RP-HPLC (C18 Phenomenex, 40 min gradient
6.93 (dd, J = 7.8, 1.3 Hz, 3H), 6.79−6.63 (t, J = 8.3 Hz, 3H), 3.66−
3.61 (m, 24H), 3.60−3.58 (m, 4H), 3.57−3.53 (q, 8H), 3.48−3.43 (t,
J = 5.96 Hz, 8H), 3.41 (m, 8H), 3.38−3.35 (t, J = 5.96 Hz, 8H), 2.94
(m, 28H), 2.21 (m, 1H), 1.61 (m, 1H), 1.08 (m, 1H) ppm. C NMR
0
−35% MeCN/H O 1% AcOH). Product-containing fractions were
2
identified by LCMS and lyophilized to obtain 14 (175 mg, 0.126
mmol, 39%) as a white solid. H NMR (500 MHz, MeOH-d ): δ 7.48
1
4
(
m, 3H), 7.36−7.31 (m, 6H), 3.68−3.59 (m, 16H), 3.58−3.56 (m,
(
176 MHz, MeOH-d ): δ 171.83, 169.47, 150.38, 147.50, 119.76,
4
2
2
H), 3.53−3.50 (m, 2H), 3.48−3.46 (m, 4H), 3.38 (m, 12H), 3.05−
1
5
19.70, 118.76, 116.77, 71.61, 71.56, 71.50, 71.26, 71.07, 70.38, 58.29,
7.72, 57.48, 53.18, 52.89, 51.77, 49.00, 40.39, 40.17, 40.13, 17.28
13
.73 (m, 16H), 2.30−2.28 (m, 9H), 2.27−2.25 (m, 9H) ppm.
C
NMR (176 MHz, MeOH-d ): δ 180.2, 175.2, 172.2, 171.9, 163.1,
4
ppm.
1
1
7
6
2
62.9, 151.3, 148.5, 147.2, 130.7, 129.0, 121.7, 121.2, 120.8, 120.0,
19.3, 119.2, 119.1, 118.3, 117.9, 117.4, 117.2, 117.1, 113.9, 71.7,
1.6, 71.6, 71.6, 71.5, 71.3, 71.2, 71.1, 71.1, 70.5, 70.4, 66.9, 66.1,
2.6, 57.5, 54.5, 54.1, 52.8, 51.8, 49.0, 43.0, 40.2, 39.9, 39.7, 39.5,
4.2, 20.7, 19.8, 18.6, 17.8, 17.4, 17.3, 17.2, 14.0, 10.6 ppm. ESI-
Benzyl (R)-2-Bromopropanoate (16). Compound 16 was
prepared according to a literature procedure from Mao et al. To a
64
solution of (R)-2-bromo-propionic acid (400 mg, 2.61 mmol, 1.0
equiv) and DCC (648 mg, 3.14 mmol, 1.2 equiv) in Et O (5 mL), a
2
solution of DMAP (16 mg, 0.13 mmol, 0.05 equiv) and BnOH (326
+
+
HRMS: 14: C H N O calcd [M + H] , = 1391.6113; measured
63
87 14 22
μL, 3.14 mmol, 1.2 equiv) in Et O (2 mL) was added, and the
+
2
[
M + H] , 1391.6165 (Δ = 5.2 ppm).
,2′,2″-(10-(2-Oxo-2-((2-(((((5aR,6aS)-1-(2-oxo-1-(4,7,10-tris-
2-((2-(2,3-dihydroxybenzamido)ethyl)amino)-2-oxoethyl)-
,4,7,10-tetraazacyclododecan-1-yl)-6,9,12-trioxa-3-azatetra-
reaction was stirred overnight. The next morning, the reaction was
concentrated in vacuo and 16 (528 mg, 2.17 mmol, 83%) could be
2
(
1
obtained via silica gel chromatography (0−1% EtOAc in PE bp 40−
1
6
0 °C) as a colorless oil. H NMR (500 MHz, CDCl ): δ 7.39−7.32
decan-14-yl)-1,4,5,5a,6,6a,7,8-octahydrocyclopropa[5,6]-
cycloocta[1,2-d][1,2,3]triazol-6yl)methoxy)carbonyl)amino)-
ethyl)amino)ethyl)-1,4,7,10-tetraazacyclododecane-1,4,7-
3
(m, 5H), 5.21 (t, J = 2.0 Hz, 2H), 4.45−4.38 (m, 1H), 1.84 (d, J = 6.9
Hz, 3H) ppm.
1
2372
J. Med. Chem. 2021, 64, 12359−12378