Notes and References
† E-mail: bcchen@gate.sinica.edu.tw
Fmoc–Gly–CH2O
O
CO2H
1 (a) J. Pless, W. Bauer, U. Briner, W. Doepfner, P. Marbach, R. Maurer,
T. J. Petcher, J.-C. Reubi and J. Vonderscher, Scand. J. Gastroenterol.,
1986, 21 (Suppl. 119), 54; (b) W. Bauer, U. Briner, W. Doepfner,
R. Haller, R. Hugenin, P. Marbach, T. J. Petcher and J. Pless, Life Sci.,
1982, 31, 1133.
6
O
CO2H
Fmoc–Phe–CH2O
7
2 D. Roemer, H. H. Buescher, R. C. Hill, J. Pless, W. Bauer, F. Cardinaux,
A. Closse, D. Hauser and R. Hugenin, Nature (London), 1977, 268, 547;
D. Roemer and J. Pless, Life Sci., 1979, 24, 621.
3 B. Cornell, J. Bioemerg. Biomembr., 1987, 19, 655; W. Neugebauer,
R. Brzezinski and G. E. Willick, in Peptide 1990, ed. E. Giralt and D.
Andreu, ESCOM, 1991, p. 188.
4 M. Solfrizzo, C. Altomare, A. Visconti, A. Bottalico and G. Perrone,
Nat. Toxins, 1994, 2, 360; S. Rebuffat, L. Conraux, M. Massias,
C. Auvin-Guette and B. Bodo, Int. J. Peptide Protein Res., 1993, 41,
74.
5 G. Weckbecker, F. Raulf, B. Stolz and C. Bruns, Pharmacol. Ther.,
1993, 60, 245.
6 (a) M. Mergler and R. Nyfeler, in Peptide 1992, ed. C. H. Schneider and
A. N. Eberle, ESCOM, 1993, p. 177; (b) W. B. Edwards, C. G. Fields,
C. J. Anderson, T. S. Pajeau, M. J. Welch and G. B. Fields, J. Med.
Chem., 1994, 37, 3749; (c) M. A. Schmidt, R. R. Wilhelm and
A. Srinivasan, in Abstracts of the Fifteenth American Peptide Sympo-
sium, June 14–19, 1997, Nashville, Tennessee, p. 2.
7 Compound 2 was prepared in two stages: (i) dimerization of acrolein
was either carried out with the standard high-pressure method [ref. 8(a)]
(37% yield) or with a recently described microwave-assisted method
(91% yield) [ref. 8(b)]; (ii) 3,4-dihydro-2H-pyran-2-carboxaldehyde
was oxidized and hydrolyzed to obtain sodium 3,4-dihydro-2H-pyran-
2-carboxylate 2 [ref. 8(c)].
8 (a) T. Shiraishi, K. Ichimura and T. Haga, Jpn. Kokai, 74 86, 373; Chem.
Abstr., 1975, 82, 156 072d; (b) H.-P. Hsieh, S.-T. Chen and K.-T. Wang,
J. Chim. Chem. Soc. (Taipei), 1997, 44, 597; (c) M. Okada,
H. Sumitomo and I. Tajima, Macromolecules, 1977, 10, 505.
9 W. Neugebauer and E. Escher, Helv. Chim. Acta, 1989, 72, 1319.
10 E. K. Kick and J. A. Ellman, J. Med. Chem., 1995, 38, 1427;
L. A. Thompson and J. A. Ellman, Tetrahedron Lett., 1994, 35, 9333.
11 Purchased from BACHEM Inc., Switzerland.
12 L. A. Carpino and G. Y. Han, J. Am. Chem. Soc., 1970, 92, 5748;
J. Martinez, J. C. Tolle and M. Bodanszky, J. Org. Chem., 1979, 44,
3596; E. Atherton, C. Bury, R. C. Sheppard and B. J. Williams,
Tetrahedron Lett., 1979, 32, 3041.
cidin3 and Trichoderma species,4 were also obtained from
Fmoc-Gly-ol13 and Fmoc-Phe-ol13 in yields of 72 and 78%,
respectively (see Scheme 1).
The novel linker was used successfully to synthesize
Octreotide. Fmoc-Thr(But)-THP-2-CO2H was attached to an
amine resin and the peptide Fmoc-d-Phe-Cys(Trt)-Phe-
d-Trp(Boc)-Lys(Boc)-Thr(But)-Cys(Trt)-Thr(But)-CH2O-
THP-CO-amide resin was synthesized stepwise using an Fmoc
protocol. After completion of the peptide synthesis, simul-
taneous cleavage of Octreotide from the resin and deprotection
of the side-chains was performed using the TFA method (TFA–
thioanisole–ethanedithiol–H2O = 0.9:0.5:0.25:0.25). Dilsul-
fide bond formation was achieved by air oxidation in aqueous
phosphate buffer at 25 °C pH 7 for 48 h monitored by HPLC.
Pure Octreotide was isolated via preparative reverse-phase
HPLC (70% total yield). Fig. 1 illustrates the time course of the
disulfide bond formation. The reduced form of Octreotide and
the final product appeared as major peaks (Fig. 1). The presence
of Octreotide was confirmed by amino acid analysis and FAB
mass spectrometry (m/z 1019.5 [M+ + 1]).
The high yields and purity (Fig. 1) of Octreotide produced
using the novel bifunctional linker demonstrate that the linker is
stable under basic Fmoc/But synthetic conditions as well as
acid-labile and easily removed from the resin to regenerate the
desired C-terminal alcohol. Furthermore, because the DHP-
2-CO2H linker first couples with the C-terminal amino alcohol
to form the first residue for SPPS, the linker can more easily
couple to any primary, secondary or even tertiary alcohols
compared to Ellman’s DHP-resin bound system.6 In conclusion,
the novel bifunctional linker can be used successfully in the
synthesis of peptide C-terminal alcohols in addition to the
preparation and screening of combinatorial peptide and non-
peptide libraries via solid-phase synthesis techniques.14
Support for this research by the National Science Council,
Taiwan, is gratefully acknowledged.
13 Purchased from NOVA Biochem Inc., Switzerland.
14 L. A. Thompson and J. A. Ellman, Chem. Rev., 1996, 96, 555.
Received in Cambridge, UK, 4th November 1997; 7/07934F
650
Chem. Commun., 1998