9778
E. R. Jarvo et al. / Tetrahedron 56 (2000) 9773±9779
H, 8.30; N, 7.60; Exact mass calcd for [C9H15N1O31H]1
requires m/z 186.1130. Found 186.1130 (FAB).
(d, J7.7 Hz, 1H), 6.37 (d, J9.5 Hz, 1H), 5.89
(d, J9.2 Hz, 1H), 5.55 (broad m, 1H), 4.91 (t, J9.5 Hz,
1H), 4.60 (dd, J6.2, 8.8 Hz, 1H), 4.54 (m, 1H), 4.45 (dd,
J7.2, 17.0 Hz, 1H), 4.31±4.23 (m, 2H), 3.91 (m, 1H), 3.75
(overlapping s and m, 5H), 3.53 (s, 3H), 3.30 (broad m, 1H),
2.96 (m, 1H), 2.89 (m, 1H), 2.26 (m, 1H), 2.18±2.07
(m, 4H), 1.95 (m, 3H), 1.84±1.68 (m, 2H), 1.51 (m, 1H),
1.43 (s, 9H), 0.94±0.82 (m, 30H); TLC Rf 0.18 (8% MeOH/
CH2Cl2); Exact mass calcd for [C46H78N10O111H]1
requires m/z 947.5930. Found 947.5948 (ESI); Analytical
HPLC: Purity of peptide 7 was assayed using a reverse
phase RP-18 X Terra (Waters) column. Conditions:
isocratic elution with 60% methanol in water, at a ¯ow
rate of 0.2 mL/min. Retention time4.7 min.
Assay of enantiomeric purity. Enantiomers of starting
material 12 and product 12-Ac were separated by chiral
GC employing a 30 m Chiraldex G-TA column (Alltech).
Conditions: Oven Temperature 1508C. Flow rate60 psi.
Retention Times: 12-Ac: Rt(R,R)5.2 min, Rt(S,S)6.3 min.
Retention Time: 12: Rt(R,R)7.5 min, Rt(S,S)10.1 min.
Proof of absolute stereochemistry. Product 12-Ac was
hydrolyzed in a fashion analogous to that employed for
1-Ac. Measurement of the optical rotation and comparison
to the literature showed the sample to be of the (R,R)-con®g-
uration. [a]D213.3 (0.77, EtOH); Literature for (S,S)-
trans-2-aminocyclopentanol´HCl: [a]D129.7 (1.95,
EtOH).18
1
Peptide 8. H NMR (CDCl3, 400 MHz) d 8.83 (d, J
8.1 Hz, 1H), 8.22 (d, J8.4 Hz, 1H), 7.75 (d, J8.4 Hz,
1H), 7.38 (s, 1H), 7.24 (m, 1H), 6.85 (m, 3H), 5.57
(d, J8.8 Hz, 1H), 4.93 (broad m, 1H), 4.78 (t, J8.4 Hz,
1H), 4.71 (t, J8.8 Hz, 1H), 4.57±4.53 (m, 2H), 4.6 (dd,
J5.1, 7.3 Hz, 1H), 4.19 (dd, J7.7, 17.9 Hz, 1H), 3.95
(t, J7.7 Hz, 1H), 3.73 (overlapping s and m, 4H), 3.65
(s, 4H), 3.27 (broad m, 1H), 3.19 (dd, J11.4, 14.2 Hz,
1H), 2.78 (dd, J3.5, 14.4 Hz, 1H), 2.18±1.95 (m, 7H),
1.83 (m, 1H), 1.73 (m, 1H), 1.63 (m, 2H), 1.44 (s, 9H),
0.98±0.86 (m, 30H); TLC Rf 0.21 (8% MeOH/CH2Cl2);
Exact mass calcd for [C46H78N10O111H]1 requires m/z
947.5930. Found 947.5911 (ESI); Analytical HPLC: Purity
of peptide 8 was assayed using a reverse phase RP-18 X
Terra (Waters) column. Conditions: isocratic elution with
60% methanol in water, at a ¯ow rate of 0.2 mL/min. Reten-
tion time4.0 min.
Peptide synthesis
Peptides were synthesized on the solid support using
commercially available HMBA-AM polystyrene resin
(Novabiochem). The carboxy terminus amino acid was
loaded as the N-a-Fmoc derivative via conventional
symmetrical anhydride loading protocols. Couplings were
performed using 4 equiv. amino acid derivative, 4 equiv.
HBTU, and 8 equiv. Hunig's base in DMF, for 3 h.
FMOC-deprotections were performed using 20% piperidine
in DMF for 20 min (to minimize diketopiperazine for-
mation, dipeptides were deprotected using 50% piperidine
in DMF for 5 min). BOC-deprotections were performed
using TFA for 30 min, followed by a free base wash with
20% piperidine in DMF for one minute. Peptides were
cleaved from solid support using
a
mixture of
Peptide 9. 1H NMR (CDCl3, 400 MHz) d 8.62 (broad s, 1H),
8.36 (d, J7.7 Hz, 1H), 8.03 (broad s, 1H), 7.70 (broad s,
1H), 7.43 (broad s, 1H), 7.05 (broad s, 1H), 6.98 (broad s,
1H), 6.69 (d, J9.5 Hz, 1H), 5.60 (broad d, J9.2 Hz, 1H),
4.76 (m, 2H), 4.67 (t, J9.4 Hz, 1H), 4.56±4.50 (m, 3H),
4.32 (m, 1H), 4.23 (m, 1H), 3.89 (t, J8.4 Hz, 1H), 3.84±
3.77 (m, 1H), 3.73 (s, 3H), 3.65 (m, 1H), 3.48 (broad s, 3H),
3.31 (broad m, 1H), 2.86 (broad m, 1H), 2.20±1.90 (m, 9H),
1.41 (s, 9H), 0.99±0.87 (m, 30H); TLC Rf 0.12 (8% MeOH/
CH2Cl2); Exact mass calcd for [C45H76N10O111H]1
requires m/z 933.5773. Found 933.5737 (ESI); Analytical
HPLC: Purity of peptide 9 was assayed using a reverse
phase RP-18 X Terra (Waters) column. Conditions:
isocratic elution with 60% methanol in water, at a ¯ow
rate of 0.2 mL/min. Retention time4.0 min.
MeOH:DMF:NEt3 (9:1:1) for 4 d. Peptides were puri®ed
using reverse phase HPLC techniques. Preparative HPLC
was performed using a reverse phase RP-18 X Terra
(Waters) column, eluting with 65±75% methanol in water,
at a ¯ow rate of 6 mL/min. The purity was checked
by analytical HPLC under similar conditions, and the
1
peptides were characterized by H NMR and electrospray
mass spectrometry.
Data for peptides
Peptide 5. 1H NMR (CDCl3, 400 MHz) d 7.84 (broad
m, 3H), 7.34 (broad s, 2H), 7.20 (broad d, J8.2 Hz, 1H),
6.75 (broad s, 1H), 6.58 (broad d, J9.2 Hz, 1H), 5.39
(broad d, J7.7 Hz, 1H), 4.66±4.52 (m, 4H), 4.44±4.34
(m, 3H), 4.11 (dd, J6.8, 16.8 Hz, 1H), 3.84±3.78
(m, 2H), 3.72 (m, 1H), 3.70 (s, 3H), 3.56 (s, 3H), 3.04±
2.90 (m, 2H), 2.22±1.98 (m, 8H), 1.80±1.53 (m, 3H), 1.40
(s, 9H), 0.97±0.85 (m, 30H); TLC Rf 0.18 (8% MeOH/
CH2Cl2); Exact mass calcd for [C46H78N10O111H]1
requires m/z 947.5930. Found 947.5932 (FAB); Analytical
HPLC: Purity of peptide 5 was assayed using a reverse
phase RP-18 X Terra (Waters) column. Conditions:
isocratic elution with 60% methanol in water, at a ¯ow
rate of 0.2 mL/min. Retention time3.4 min.
1
Peptide 10. H NMR (CDCl3, 400 MHz) d 8.49 (d, J
8.8 Hz, 1H), 7.80 (d, J8.8 Hz, 1H), 7.61 (d, J7.3 Hz,
1H), 7.38 (broad s, 1H), 7.18 (m, 1H), 7.08 (broad m,
1H), 6.82 (broad s, 1H), 6.68 (broad s, 1H), 5.71
(d, J8.4 Hz, 1H), 5.00 (m, 1H), 4.68 (m, 1H), 4.50±4.42
(m, 3H), 4.36 (m, 1H), 3.97±3.91 (m, 2H), 3.87±3.83
(m, 2H), 3.72 (s, 3H), 3.66 (m, 1H) 3.51 (s, 3H), 3.08 (dd,
J7.2, 15.7 Hz, 1H), 2.96 (dd, J7.0, 14.6 Hz, 1H) 2.19±
1.97 (m, 9H), 1.71±1.65 (m, 2H), 1.45 (s, 9H), 0.92±0.85
(m, 30H); TLC Rf 0.21 (8% MeOH/CH2Cl2); Exact mass
calcd for [C46H78N10O111H]1 requires m/z 947.5930.
Found 947.5948 (ESI); Analytical HPLC: Purity of peptide
10 was assayed using a reverse phase RP-18 X Terra
1
Peptide 7. H NMR (CDCl3, 400 MHz) d 8.45 (d, J
8.8 Hz, 1H), 8.22 (d, J8.4 Hz, 1H), 7.79 (broad m, 1H),
7.63 (d, J8.8 Hz, 1H), 7.27 (s, 1H), 6.80 (s, 1H), 6.57