M. Sienczyk, J. Oleksyszyn / Tetrahedron Letters 45 (2004) 7251–7254
7253
Table 1. Inhibitory activity of new a-aminophosphonate diphenyl
esters, aromatic analogues of arginine towards trypsin
2a: White, pale yellow solid, mp 120ꢁC [Found C, 66.51;
H, 4.97; N, 5.80; P, 6.32. C27H25N2O5P requires C, 66.39;
H, 5.16; N, 5.73; P, 6.34%]; 31P NMR (CDCl3): 15.72 (s);
1H NMR (CDCl3): 3.88 (s, 2H), 5.09 (dd, J = 12.2,
28.7Hz, 2H), 5.48 (dd, J = 9.9, 21.8Hz, 1H), 5.93 (d,
J = 7.7Hz, 1H), 6.62–7.38 (m, Ar–H, 19H); 13C NMR
(CDCl3): 52.9 (d, J = 158.7Hz), 67.51, 115.00 (d,
J = 7.2Hz), 115.65, 118.63 (d, J = 6.64Hz), 120.51 (dd,
J = 4.3, 6.4Hz), 125.35 (d, J = 4.0Hz), 128.22, 128.28,
128.56, 129.69 (d, J = 8.1Hz), 129.84, 135.18, 136.03,
146.51, 150.14 (d, J = 9.5Hz), 155.55 (d, J = 9.0Hz).
3a: White crystals, mp 86-88ꢁC [Found C, 62.11; H, 6.21;
N, 7.45; P, 4.40. C38H43N4O9P requires C, 62.46; H, 5.93;
N, 7.67; P, 4.24%]; 31P NMR (CDCl3): 15.22 (s); 1H NMR
(CDCl3): 1.43 (s, 9H), 1.49 (s, 9H), 5.07 (dd, J = 12.2,
33.45Hz, 2H), 5.55 (dd, J = 9.8, 22.3Hz, 1H), 6.04 (d,
J = 3.1Hz, 1H), 6.89–7.73 (m, Ar–H, 19H), 10.38 (s, 1H),
11.60 (s, 1H); 13C NMR (CDCl3): 28.17, 52.73 (d,
J = 160.0Hz), 67.56, 79.75, 83.87, 120.53 (d, J = 4.1Hz),
121.56, 122.71, 124.50, 125.38 (d, J = 4.1Hz), 128.27,
128.56, 129.50, 129.73 (d, J = 3.6Hz), 134.86, 136.00,
137.44, 150.15, 153.36, 155.44, 161.40, 163.4.
Compound
IC50 (lM)
4a
4b
0.122
13
10min at room temperature before the addition of sub-
strate. Our observation proved that longer preincuba-
tion times do not seem to change the IC50 values.
Surprisingly, we have noticed that compound 4a is a
more active inhibitor of trypsin than of uPA
(IC50 = 1.6lM, Ref. 6, Table 1).
Additionally, our preliminary results showed that these
compounds are potent inducers of apoptosis in human
cancer cell lines; these results will be published sepa-
rately in due course.
In conclusion, we have presented an alternative route
for the synthesis of novel protected a-aminophosphonic
diphenyl esters, aromatic mimetics of arginine, which
appears to be more efficient if compared to current
methods presented in the literature. The compounds
obtained are potent inhibitors for trypsin-like enzymes
even as racemic mixtures. The new challenge in this area
is the synthesis of optically pure a-aminophosphonates
of Cbz-ArgP(OPh)2, Cbz-HomoArgP(OPh)2, Cbz-(3-
GuPhg)P(OPh)2, Cbz-(4-GuPhg)P(OPh)2. We are cur-
rently at advanced stages in the synthesis of pure
enantiomers of these phosphonic analogues of arginine.
1b: White solid, mp 160–161ꢁC [Found C, 62.58; H, 4.48;
N, 5.48; P, 6.04. C27H23N2O7P requires C, 62.55; H, 4.47;
N, 5.40; P, 5.97%];31P NMR (CDCl3): 13,66 (s); 1H NMR
(CDCl3): 5.09 (q, J = 12.1Hz, 2H), 5.65 (dd, J = 9.0,
23.4Hz, 1H), 6.13 (dd, J = 5.7, 8.8Hz, 1H), 6.91–8.19 (m,
Ar–H, 19H); 13C NMR (CDCl3): 52.60 (d, J = 155.93Hz),
67.89, 120.22 (dd, J = 4.3, 11.8Hz), 123.94, 125.79,
128.27, 128.58 (d, J = 9.7Hz), 129.05 (d, J = 5.6Hz),
129.92, 135.67, 141.65, 147.96, 149.78 (d, J = 9.1Hz),
155.45.
2b: White, pale yellow solid, mp 176–178ꢁC [Found C,
66.23; H, 5.25; N, 5.68; P, 6.32. C27H25N2O5P requires C,
66.39; H, 5.16; N, 5.73; P, 6.34%]; 31P NMR (DMSO):
1
17.38 (s); H NMR (DMSO): 5.02 (dd, J = 12.5, 26.3Hz,
2H), 5.13 (s, 2H), 5.28 (dd, J = 10.1, 20.1Hz, 1H), 6.47–
7.30 (m, Ar–H, 19H), 8.61 (d, J = 10.1Hz, 1H); 13C NMR
(DMSO): 52.97 (d, J = 159.3Hz), 66.52, 114.06, 120.84 (t,
J = 4.6Hz), 121.07, 125.63 (d, J = 6.6Hz), 128.37 (d,
J = 3.5Hz), 128.84, 129.87 (d, J = 6.3Hz), 130.26,
137.24, 149.24, 150.58 (q, J = 11.0Hz), 156.44 (d,
J = 8.5Hz).
3b: White, pearl crystals, 117–118ꢁC [Found C, 59.48; H,
6.50; N, 7.17; P, 4.05. C38H43N4O9P · 2H2O requires C,
59.52; H, 6.18; N, 7.31; P, 4.05%]; 31P NMR (CDCl3):
15.39 (s); 1H NMR (CDCl3): 1.50 (s, 9H), 1.53 (s, 9H),
5.10 (dd, J = 12.2, 25.0Hz, 2H), 5.53 (dd, J = 9.7, 22.0Hz,
1H), 5.79 (d, J = 6.9Hz, 1H), 6.90–7.64 (m, Ar–H, 19H),
10.36 (s, 1H), 11.60 (s, 1H); 13C NMR (CDCl3): 28.16 (d,
J = 7.2Hz), 52.41 (d, J = 154.0Hz), 67.59, 79.75, 83.87,
120.49 (t, J = 3.3Hz), 122.44, 125.40, 128.27 (d,
J = 5.7Hz), 128.58, 128.80 (d, J = 8.5Hz), 129.74,
130.36, 135.96, 137.31, 150.01 (d, J = 11.6Hz), 155.41,
153.43, 159.57, 163.49.
References and notes
1. Duffy, M. J. Curr. Pharm. Des. 2004, 10, 39–49.
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Hamilton, R.; Walker, B. J.; Walker, B. Tetrahedron Lett.
1993, 34, 2847–2850.
5. Cheng, L.; Goodwin, C.; Scully, M. F.; Kakkar, V. V.;
Claeson, G. Tetrahedron Lett. 1991, 32, 7333–7336.
6. Joossens, J.; Van der Veken, P.; Lambeir, A.-M.; August-
yns, K.; Haemers, A. J. Med. Chem. 2004, 47, 2411–2413.
7. This work is the subject of patent application (P368474).
8. Oleksyszyn, J.; Subotkowska, L.; Mastalerz, P. Synthesis,
1979, 985–986.
10. Duringpeptide synthesis we discovered that the hydro-
bromide salt of the p-nitro derivative is highly unstable in
alkaline medium––even addition of Et3N prevents peptide
formation. The Cbz-protected derivative is more stable,
but after 12h in weak-alkaline solution (DMSO–Et3N) we
observed, by 31P NMR monitoring, formation of a
degradation product. This abnormal behaviour and
probable mechanism leadingto this instability, is currently
the subject of additional investigations.
11. Wiesner, J.; Wißner, P.; Dahse, H.-M.; Jomaa, H.;
Schlitzer, M. Bioorg. Med. Chem. Lett. 2001, 9, 785–792.
12. (a) Cucha, S.; Costa, M. B.; Napolitano, H. B.; Lariucci,
C.; Vencato, I. Tetrahedron 2001, 57, 1671–1675; (b) Kim,
K. S.; Qian, L. Tetrahedron Lett. 1993, 34, 7677–7680.
9. 1H, 13C NMR and 31P NMR spectra were recorded at
300.13, 75.47 and 121.50MHz, respectively.
1a: White crystals, mp 150ꢁC [Found C, 62.36; H, 4.70; N,
5.30; P, 5.80. C27H23N2O7P requires C, 62.55; H, 4.47; N,
5.40; P, 5.97%]; 31P NMR (CDCl3): 17.31 (s); 1H NMR
(CDCl3): 5.12 (q, J = 12.1Hz, 2H), 5.67 (dd, J = 8.8,
23.2Hz, 1H), 6.16 (dd, J = 6.0, 9.0Hz, 1H), 6.94–8.35 (m,
Ar–H, 19H); 13C NMR (CDCl3): 52.36 (d, J = 155.8Hz),
67.91, 120.20 (dd, J = 4.4, 12.4Hz), 122.96 (d, J = 6.1Hz),
123.56, 125.75 (d, J = 3.0Hz), 128.28, 128.57 (d,
J = 11.1Hz), 129.83, 129.92, 134.19, 135.65, 136.72,
148.44, 150.07, 155.6.