L. Vezenkov et al. / Bioorg. Med. Chem. 23 (2015) 3237–3247
3245
solution and heated. All automated flash chromatography were
a
yellow solid (13.3 g, 80%). Purity = 90%;
t
R
= 2.36 min; MS
performed on Biotage Isolera Flash Purification Systems using
commercial silica gel cartridges.
30 3 5
(ESI+): m/z = 428 [M+H]+; HRMS m/z calculated for C23H N O
1
(M+H)+ 428.2180, found 428.2176. H NMR (DMSO-d
6
) d (ppm):
9
.78 (s, 1H), 8.34 (t, 1H, J = 5.4 Hz), 7.57 (d, 2H, J = 8.4 Hz), 7.30–
5
.3.1. (S)-Benzyl 2-(2-((tert-butoxycarbonyl)amino)-3-
phenylpropanamido)acetate (34)
Boc- -phenylalanine (25.0 g, 94.3 mmol, 1.0 equiv) was dis-
solved in NMP (100 mL). N-Methylmorpholine (46.6 mL,
24.1 mmol, 4.5 equiv) and HBTU (35.8 g, 94.3 mmol, 1.0 equiv)
7.24 (m, 6H), 7.22–7.18 (m, 1H), 7.05 (d, 1H, J = 8.2 Hz), 5.11 (t,
1H, J = 5.7 Hz), 4.44 (d, 2H, J = 5.6 Hz), 4.21 (td, 1H, J = 10.4 and
4.2 Hz), 3.96–3.79 (m, 2H), 3.04 (dd, 1H, J = 13.7 and 4.2 Hz), 2.78
(dd, 1H, J = 13.7 and 10.4 Hz), 1.31 (s, 9H). C NMR (DMSO-d ) d
6
(ppm): 172.6, 167.9, 155.9, 138.7, 138.0, 137.8, 129.7, 128.5,
127.4, 126.6, 119.3, 78.6, 63.0, 56.3, 43.2, 37.7, 28.6.
L
1
3
4
were added to the reaction mixture. The reaction mixture was stir-
red 5 min at room temperature. Glycine benzyl ester p-toluenesul-
fonate salt (34.9 g, 103.8 mmol, 1.1 equiv) was added. The reaction
mixture was stirred 5 h at room temperature. The reaction mixture
was diluted in EtOAc (800 mL) and was washed twice with bri-
ne/satd aq NaHCO
once with brine. The organic phase was dried over Na
centrated under reduced pressure. During the concentration the
product precipitated to afford 34 as a white solid (31.0 g, 80%).
5.3.4. 7-(Allyloxy)-7-oxoheptanoic acid
A solution of DCC (3.64 g, 17.65 mmol, 1.0 equiv) in THF (22 mL)
was added drop-wise via an addition funnel over 1 h to a solution
of pimelic acid (14.1 g, 88.24 mmol, 5.0 equiv), allyl alcohol
(1.20 mL, 17.65 mmol, 1.0 equiv) and DMAP (0.216 g, 1.76 mmol,
0.1 equiv) in THF (133 mL). The reaction mixture was stirred 3 days
at room temperature. The reaction mixture was filtered through
Celite and washed with THF. The filtrate was concentrated under
reduced pressure. The crude product was purified by flash chro-
matography on silica gel 120 g column (hexanes/EtOAc 10:0 to
50:50 (v/v) in 30 min) to afford 7-(allyloxy)-7-oxoheptanoic acid
3
solution 50/50 (v/v), twice with 1 N HCl, and
SO and con-
2
4
Purity = 100%; t
R
= 2.86 min; MS (ESI+): m/z = 413 [M+H]+; HRMS
(M+H)+ 413.2071, found 413.2078.
) d (ppm): 8.44 (t, 1H, J = 5.8 Hz), 7.42–7.31
m, 5H), 7.27 (d, 4H, J = 4.2 Hz), 7.19 (dd, 1H, J = 8.4 and 4.2 Hz),
m/z calculated for C23
H NMR (DMSO-d
(
29 2 5
H N O
1
6
6
1
.96 (d, 1H, J = 8.8 Hz), 5.15 (s, 2H), 4.24–4.20 (m, 1H), 3.99 (dd,
H, J = 17.5 and 6.0 Hz), 3.91 (dd, 1H, J = 17.5 and 5.5 Hz), 2.99
as colorless oil (3.15 g, 78%). MS (ESI+): m/z = 201 [M+H]+; 1
NMR (CDCl ) d (ppm): 5.94 (ddt, 1H, J = 17.2, 10.4 and 5.7 Hz),
H
3
(
dd, 1H, J = 13.8 and 3.7 Hz), 2.72 (dd, 1H, J = 13.8 and 10.9 Hz),
.25 (s, 9H). C NMR (DMSO-d ) d (ppm): 172.9, 170.1, 155.7,
6
38.7, 136.4, 129.6, 128.9, 128.5, 128.4, 128.4, 126.6, 78.4, 66.3,
6.0, 41.3, 37.9, 28.6.
5.34 (dq, 1H, J = 17.2 and 1.4 Hz), 5.26 (dq, 1H, J = 10.4 and
1.4 Hz), 4.60 (dt, 2H, J = 5.7 and 1.4 Hz), 2.39 (t, 2H, J = 7.4 Hz),
1
3
1
1
5
2.38 (t, 2H, J = 7.4 Hz), 1.73–1.65 (m, 4H), 1.46–1.40 (m, 2H). 13
C
3
NMR (CDCl ) d (ppm): 179.1, 173.2, 132.2, 118.2, 65.0, 34.0, 33.7,
2
8.5, 24.5, 24.3.
5
.3.2. (S)-2-(2-((tert-Butoxycarbonyl)amino)-3-
phenylpropanamido)acetic acid (35)
5.3.5. (S)-Allyl-7-((1-((2-((4-(hydroxymethyl)phenyl)amino)-2-
oxoethyl)amino)-1-oxo-3-phenylpropan-2-yl)amino)-7-
oxoheptanoate (38)
Compound 34 (11.0 g, 26.7 mmol, 1.0 equiv) was dissolved in
EtOH (200 mL) and DMF (60 mL). 10% palladium on activated char-
coal (4.89 g) and ammonium formate (15.1 g, 240.0 mmol, 9 equiv)
were added and the reaction mixture was stirred overnight at
room temperature. The reaction mixture was filtered on a bed of
Celite and the EtOH was evaporated under reduced pressure. The
remaining DMF was diluted in EtOAc and the organic phase was
washed twice with 0.5 N HCl and twice with brine and was dried
Compound 36 (0.190 g, 0.64 mmol, 0.4 equiv) was dissolved in
TFA (0.4 mL) at 0 °C and the reaction mixture was stirred for
30 min at room temperature. The TFA was concentrated to dryness
and the obtained brown oil was dissolved in dioxane (2.0 mL) and
water (2.0 mL). A 2 N aqueous NaOH solution was added to the
reaction mixture. After 2 h of stirring at room temperature (brown
reaction mixture), the pH was adjusted to neutral with 1 N HCl. The
dioxane was evaporated and the remaining solution was lyophi-
lized to afford compound 37 as a white solid (270 mg, quantitative
over Na
compound 35 as
= 1.70 min; MS (ESI+): m/z = 345 [M+Na]+; HRMS m/z calculated
2
SO
4
and concentrated under reduced pressure to afford
a
white solid (7.64 g, 89%). Purity = 85%;
t
R
1
for C16
H
22
N
O
2 5
Na (M+Na)+ 345.1421, found 345.1432. H NMR
yield). Purity = 100%; t
R
= 1.12 min; MS (ESI+): m/z = 328 [M+H]+.
acid (1.94 g, 9.71 mmol,
(
DMSO-d ) d (ppm): 12.6 (br s, 1H), 8.24 (t, 1H, J = 5.8 Hz), 7.30–
6
7-(Allyloxy)-7-oxoheptanoic
7
1
.24 (m, 4H), 7.20–7.18 (m, 1H), 6.92 (d, 1H, J = 8.8 Hz), 4.21 (td,
H, J = 10.7 and 3.7 Hz), 3.84 (dd, 1H, J = 17.5 and 5.8 Hz), 3.76
1.5 equiv), HBTU (3.68 g, 9.71 mmol, 1.5 equiv) and NMM
(2.14 mL, 19.42 mmol, 3.0 equiv) were solubilized in NMP
(28.0 mL). This reaction mixture was added dropwise via an addi-
tion funnel to a solution of compound 37 (2.86 g, 6.47 mmol,
1.0 equiv) and the reaction mixture was stirred overnight at room
temperature. The reaction mixture was diluted in EtOAc and
(
dd, 1H, J = 17.5 and 5.8 Hz), 3.02 (dd, 1H, J = 13.8 and 3.7 Hz),
2
.73 (dd, 1H, J = 13.8 and 10.7 Hz), 1.29 (s, 9H). 13C NMR (DMSO-
) d (ppm): 172.5, 171.6, 155.7, 138.7, 129.6, 128.4, 126.6, 78.4,
d
6
5
6.0, 41.2, 38.0, 28.6.
washed successively with 5% aq NaHCO
citric acid solution, water and brine. The organic phase was dried
over Na SO and concentrated under reduced pressure to afford a
brown solid. The crude product was purified by flash chromatogra-
phy on silica gel 80 g column (CH Cl /MeOH 10:0 to 95:5 (v/v) in
30 min) to afford 38 as white solid (2.89 mg, 87%).
Purity = 87%; t
= 2.38 min; MS (ESI-): m/z = 508 [MꢀH]ꢀ; HRMS
m/z calculated for
(MꢀH)ꢀ 508.2453, found
) d (ppm): 9.13 (s, 1H), 7.90 (t, 1H,
3
solution, water, 10% aq
5
2
.3.3. (S)-tert-Butyl (1-((2-((4-(hydroxymethyl)phenyl)amino)-
-oxoethyl)amino)-1-oxo-3-phenylpropan-2-yl)carbamate (36)
Compound 35 (12.0 g, 37.7 mmol, 1.0 equiv) was dissolved in
2
4
NMP (80 mL). NMM (8.3 mL, 75.4 mmol, 2.0 equiv) and HBTU
14.8 g, 39.1 mmol, 1.05 equiv) were added to the reaction mixture
2
2
(
a
and heated with hot air gun until the mixture was homogeneous.
This reaction mixture was added dropwise over 1 h via an addition
funnel to a solution of 4-aminobenzyl alcohol (6.02 g, 49.0 mmol,
R
28 34 3 6
C H N O
1
508.2453. H NMR (acetone-d
6
1
3
.3 equiv) in NMP (30 mL) and the reaction mixture was stirred
0 min at room temperature. The reaction mixture was diluted in
J = 5.4 Hz), 7.78 (d, 2H, J = 8.5 Hz), 7.63 (d, 1H, J = 6.0 Hz), 7.33–
7.26 (m, 6H), 7.26–7.19 (m, 1H), 5.95 (ddt, 1H, J = 17.2, 10.4 and
5.6 Hz), 5.31 (dq, 1H, J = 17.2 and 1.6 Hz), 5.20 (dq, 1H, J = 10.4
and 1.6 Hz), 4.61–4.47 (m, 5H), 4.08 (dd, 1H, J = 16.9 and 6.6 Hz),
3.81 (dd, 1H, J = 16.9 and 5.4 Hz), 3.22 (dd, 1H, J = 13.9 and
5.8 Hz), 3.01 (dd, 1H, J = 13.9 and 9.0 Hz), 2.25 (dd, 4H, J = 15.4
EtOAc and washed successively twice with saturated aq NaHCO
solution, twice with 1 N HCl solution and brine. The organic phase
was dried over Na SO and concentrated under reduced pressure
to afford (S)-tert-butyl (1-((2-((4-(hydroxymethyl)phenyl)amino)-
-oxoethyl)amino)-1-oxo-3-phenylpropan-2-yl)carbamate (36) as
3
2
4
1
3
2
and 7.7 Hz), 1.62–1.48 (m, 4H), 1.27 (m, 2H). C NMR (acetone-