3168 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 17
Walpole et al.
δ 1.63-1.94 (3H, m, CH2 pyrrolidine), 2.08-2.25 (1H, m, CH2
pyrrolidine), 2.72 (0.6 × 3H, s, NCH3 major), 2.90 (0.4 × 3H,
s, NCH3 minor), 3.00-3.31 (4H, m, CH2Nap, NCH2 pyrroli-
dine), 4.28 (0.6 × 1H,, dAB, J AB ) 14 Hz, NCHAHBPh major),
4.25-4.56 (2.8 H, m, ArCH2NH, NCHAHBPh minor), 4.76 (0.6
× 1H, dAB, J AB ) 14 Hz, NCHAHBPh major), 4.82-4.98 (1H,
m, pyrrolidine), 5.16-5.32 (1H, m, CHCH2Nap), 6.92-7.05
(2H, m, ArH), 7.08-7.52 (11H, m, ArH), 7.54-7.83 (5H, m,
ArH); IR (KBr) 3630-3170s, br, 1636 s, 1533 m cm-1; MS m/e
(FAB) 583 (MH)+ (53%), 265 (93%), 122 (100%). Anal.
(C34H35N4O3Cl‚0.25H2O) C, H, N.
N-(N,N′-Di-ter t-bu toxycar bon ylam idin o)-(S)-pr olyl-(S)-
3-(2-n a p h th yl)a la n yl-N-ben zylm eth yla m id e. To (S)-pro-
lyl-(S)-3-(2-naphthyl)alanyl-N-benzyl-N-methylamide (207 mg,
0.5 mmol), 1,3-bis-tert-butoxycarbonylthiourea (138m mg, 0.5
mmol), and Et3N (0.17 mL, 1.25 mmol) in DMF (2 mL) cooled
in ice was added HgCl2 (150 mg, 0.55 mmol). The reaction
mixture was stirred in ice for 2 h. The reaction mixture was
poured into water and extracted with EtOAc (3 × 50 mL). The
combined organic extracts were dried (Na2SO4) and filtered
through silica. The colorless filtrate was concentrated to afford
a white solid (348 mg, 0.5 mmol, 100%): 1H NMR (CDCl3)
mixture of two rotamers δ 1.46 (0.3 × 18H, s, t-Bu major), 1.51
(0.7 × 18H, s, t-Bu minor), 1.68-2.01 (4H, m, CH2 pyrrolidine),
2.64 (0.7 × 3H, s, NCH3 major), 2.85 (0.3 × 3H, s, NCH3
minor), 3.17-3.36 (2H, m, NCH2 pyrrolidine), 3.36-3.63 (2H,
m, CH2Nap), 4.20-4.37 (1H, m, CH pyrrolidine), 4.55-4.81
(2H, m, CH2Ph), 5.12-5.38 (1H, m, CHCH2Nap), 6.83-6.96
(2H, m, ArH), 7.03-7.19 (3H, m, ArH), 7.46-7.52 (3H, m,
ArH), 7.52-7.65 (1H, m, ArH), 7.65-7.84 (4H, m), 10.12-10.28
(1H, s, NH); IR (KBr) 3350-3200 s, br, 2978 m, 2931 s, 1749
s, 1634 s, 1605 s cm-1; MS m/e (FAB) 658 (MH)+ (32%), 458
(100%).
MS m/e (FAB) 582 (MH)+ (100%). Anal. (C34H36N5O2‚
1.0H2O‚1.3C2HF3O2) C, H, N, F.
2-Ch lor op h en ylt h ioca r b a m oyl-(S)-p r olyl-(S)-p h en yl-
a la n yl-N-ben zylm eth yla m id e, 5a . H-Pro-Phe-benzylmethy-
lamide36 was treated with 2-chlorophenyl isothiocyanate as
described above for 3a . The title compound was obtained in
63% yield after crystallization (hexane/EtOAc): TLC (CH2Cl2/
MeOH 14:1) Rf 0.76; 1H NMR (CDCl3) mixture of two rotamers
δ 2.05-2.27 (4H, m, CH2CH2), 2.67 (0.7 × 3H, s, NCH3, major),
2.87 (0.3 × 3H, s, NCH3, minor), 3.07 (0.3 × 2H, d, J ) 9.5
Hz, PhCH2), 3.09 (0.7 × 2H, d, J ) 8.0 Hz, PhCH2), 3.65-3.83
(2H, m, NCH2), 4.30 (0.3 × 1H, dAB, J ) 17.4 Hz, PhCHAHBN,
minor), 4.39 (0.7 × 1H, dAB, J ) 14.7 Hz, PhCHAHBN, major),
4.60 (1H, dAB, J ) 14.7 Hz, PhCHAHBN, both), 5.02-5.27 (2H,
m, R-H, R-H), 6.98-7.52 (14H, m, ArH, NH, NH), 8.23 (1H, d,
J ) 9 Hz, ArH); IR 3327 (m), 3239 (br), 1629 (s), 1520 (s), 1383
(m), 1344 (m) cm-1; MS m/e (FAB) 535 (MH+), 269 (100%).
Anal. (C29H31N4O2SCl) C, H, N.
2-Nitr op h en ylca r ba m oyl-(S)-p r olyl-(S)-3-(2-n a p h th yl)-
a la n yl-N-ben zyl-N-m eth yla m id e, 5f. (S)-Prolyl-(S)-3-(2-
naphthyl)alanyl-N-benzyl-N-methylamide38 was treated with
2-nitrophenyl isocyanate as described for 3a . Flash chromato-
graphic purification (ethyl acetate/hexane 2:1) yielded the title
compound in 83% yield: TLC (EtOAc/hexane 1:1) Rf 0.1; mp
79-82 °C; 1H NMR (CDCl3) mixture of two rotamers δ 1.71-
2.05 (3H, m, CH2 pyrrolidine), 2.15-2.33 (1H, m, CH2 pyrro-
lidine), 2.78 (0.6 × 3H, s, NCH3 major), 2.94 (0.4 × 3H, s, NCH3
minor), 3.14-3.41 (4H, m, CH2Nap, NCH2 pyrrolidine), 4.32-
4.75 (3H, m, NCH2Ph. CH pyrrolidine), 5.36 (1H, q, J ) 7.55
Hz, CHCH2Nap), 7.05-7.74 (15H, m, ArH), 8.22 (1H, d, J )
8.5 Hz, ArH), 8.75 (1H, d, J ) 8.79 Hz, ArH), 9.90 (0.4 × 1H,
s, NH minor), 10.00 (0.6 × 1H, s, NH minor); IR (KBr) 3600-
3190 w, br, 1681 s, 1645 s, 1610 m, 1586 s, 1501 s, 1452 m,
1437 s, 1355 m cm-1; MS m/e (FAB) 580 (MH)+ (79%), 459
(8%), 416 (24%), 319 (24%), 262 (80%), 234 (91%), 170 (100%);
N-(N,N′-Di-ter t-b u t oxyca r b on yla m id in o-N-[2-ch lor o-
b en zyl])-(S)-p r olyl-(S)-3-(2-n a p h t h yl)a la n yl-N-b en zyl-
m eth yla m id e. To N-(N,N′-di-tert-butoxycarbonylamidino)-
(S)-prolyl-(S)-3-(2-naphthyl)alanyl-N-benzylmethylamide (165
mg, 0.25 mmol) dissolved in DMF (5 mL) was added NaH (12
mg, 0.3 mmol). The reaction was stirred at room temperature
for 5 min before 2-chlorobenzyl bromide (37 mL, 0.28 mmol)
was added. The reaction mixture was stirred at room tem-
perature for 2 h. The reaction mixture was poured into water
and extracted with EtOAc (3 × 50 mL). The combined organic
extracts were washed with brine, dried (MgSO4), and concen-
trated. The residue was purified by flash column chromatog-
raphy (hexane/EtOAc 1:2) to afford N-(N,N′-di-tert-butoxy-
carbonylamidino-N-[2-chlorobenzyl])-(S)-prolyl-(S)-3-(2-naph-
thyl)alanyl-N-benzylmethylamide (98 mg, 50%): 1H NMR-
(CDCl3) mixture of two rotamers δ 1.29-1.63 (18H, m, t-Bu),
1.63-1.97 (4H, m, CH2 pyrrolidine), 2.67 (0.3 × 3H, s, NCH3
minor), 2.82 (0.7 × 3H, s, NCH3 major), 2.97-3.48 (4H, m,
NCH2 pyrrolidine, CH2Nap), 4.15-4.37 (4H, m, NHCH2Ar,
NCH2Ph), 4.42-4.69 (1H, m, CH pyrrolidine), 4.88-5.29 (1H,
m, CHCH2Nap), 6.66-7.15 (6H, m, ArH), 7.15-7.31 (2H, m,
ArH), 7.31-7.56 (5H, m, ArH), 7.56-7.83 (4H, m, ArH); IR-
(KBr) 2977 m, 1722 s, 1680 s, 1653 s, 1600 s cm-1; MS m/e
(FAB) 782 (MH)+ (98%), 582 (100%).
23
[R]D -60.6° (c 0.53, CHCl3). Anal. (C33H33N5O5‚0.5H2O) C,
H, N.
N-Boc-N′-(2-n itr op h en yl)th iou r ea . To a solution of 2-ni-
trophenylthiourea (0.59 g, 3 mmol) in dry THF (60 mL) was
added NaH (180 mg, 4.5 mmol), causing a red coloration. The
mixture was cooled on ice, and di-tert-butyl dicarbonate (0.72
g, 3.3 mmol) in THF (10 mL) was added. After 12 h of stirring,
the reaction mixture was evaporated in vacuo and then
redissolved in EtOAc (100 mL). Then 2 M NaHCO3 (10 mL)
was added and the red aqueous layer removed. The aqueous
layer was acidified to pH 4 with 10% citric acid and extracted
with EtOAc (50 mL). The orange organic phase was separated,
washed with brine, and dried over MgSO4. The crude product
was purified by flash column chromatography (hexane/EtOAc
5:1) to give a yellow solid, 340 mg (38%): TLC (hexane/EtOAc
1:1) Rf 0.8; 1H NMR (CDCl3) δ 1.54 (9H, s, Boc), 7.37 (1H, t, J
) 8.2 Hz, ArH), 7.65 (1H, t, J ) 8.2 Hz, ArH), 8.08 (2H, d, J
) 8.2 Hz, ArH and NH), 8.43 (1H, d, J ) 8.2 Hz, ArH), 12.50
(1H, br s, NH); IR 3178 (s), 1722 (s), 1609 (m), 1584 (m), 1552
(s), 1520 (s), 1369 (s), 1339 (s) cm-1; MS m/e (FAB) 298 (MH+),
242 (100%).
N,N′-Bisbu tyloxyca r bon yl-N-(2-n itr op h en yla m id in o)-
(S )-p r olyl-(S )-3-(2-n a p h t h yl)a la n yl-N -b e n zylm e t h yl-
am ide. N-Boc-N′-(2-nitrophenyl)thiourea (130 mg, 0.44 mmol),
triethylamine (0.15 mL, 1 mmol), and (S)-prolyl-(S)-3-(2-
naphthyl)alanyl-N-benzyl-N-methylamide (183 mg, 0.44 mmol)
in DMF (5 mL) was cooled in an ice bath. Mercury(II) chloride
(130 mg, 0.48 mmol) was added and the mixture stirred for 1
h. After this time the reaction mixture was diluted with
EtOAc and washed with water. The organic phase was
separated, washed with brine, dried over Na2SO4, and then
filtered through a pad of Celite. Evaporation yielded a yellow
solid which was purified by flash column chromatography
(hexane/EtOAc 1:1) to give the title compound (269 mg, 90%):
N-Am idin o-N-[2-ch lor oben zyl]-(S)-pr olyl-(S)-3-(2-n aph -
th yl)a la n yl-N-ben zylm eth yla m id e, 4a j. N-(N,N′-di-tert-
butoxycarbonylamidino-N-[2-chlorobenzyl])-(S)-prolyl-(S)-3-(2-
naphthyl)alanyl-N-benzylmethylamide (181 mg, 0.23 mmol)
was treated with a mixture of trifluoroacetic acid (2 mL) and
CH2Cl2 (2 mL). The reaction mixture was stirred at room
temperature for 4 h. The reaction mixture was concentrated
and purified by preparative HPLC (gradient run (90:10-0:100
H2O:acetonitrile) to afford a cream-colored foam (63 mg, 0.1
1
mmol, 47%): mp 73-76 °C; H NMR (CDCl3) mixture of two
rotamers δ 1.84-2.32 (4H, m, CH2 pyrrolidine), 2.72 (0.7 ×
3H, s, NCH3 major), 2.82 (0.3 × 3H, s, NCH3 minor), 3.03-
3.25 (2H, m, CH2Nap), 3.38-3.81 (2H, m, NCH2 pyrrolidine),
4.20-4.81 (5H, m, NHCH2Ar, CH pyrrolidine, NCH2Ph), 5.02-
5.25 (1H, m, CHCH2Nap), 6.77-7.82 (18H, m, ArH, NH), 8.30-
1
TLC (hexane/EtOAc 1:1) Rf 0.3; H NMR (CDCl3) mixture of
two rotamers δ 1.34 and 1.43 (9H, s, Boc), 1.6-2.2 (4H, m,
CH2CH2), 2.85 and 2.9 (3H, s, NCH3), 3.2-3.7 (4H, m, ArCH2,
NCH2), 4.3-4.7 (3H, m, PhCH2 and R-H), 5.2 (1H, m, R-H),
6.9-7.2 (8H, m, ArH, NH), 7.3-7.5 (4H, m, ArH), 7.6-7.9 (6H,
8.45 (1H, ArH); IR (KBr) 3510-3100 w, br, 1663 s, 1632 s cm-1
;