Mass spectra were measured on Bruker Esquire 6000 (ESI) and
VG Autospec (FAB) instruments, only characteristic fragments
are given for the most abundant isotope peak. The solvent flow
rate for the ESI measurements was 4 ml/min with a nebulizer
pressure of 10 psi and a dry gas flow rate of 5 l min-1 at a dry gas
temperature of 300 ◦C. IR spectra were recorded on pure solid
samples with a Bruker Tensor 27 IR spectrometer equipped with a
Pike MIRacle Micro ATR accessory. The elemental composition
of the compounds was determined with a VarioEL analyzer
from Elementar Analysensysteme GmbH. The analytical HPLC
measurements were performed on a Varian ProStar instrument
d 8.70 (s, br, 3H, H(3-pz)), 8.59 (s, br, 3H, H(5-pz)), 6,79 (s, br,
3H, H(4-pz)), 5.60 (s, 2H, OCH2C(pz)3), 4.71 (d, 2H, OCH2CC,
4
4
J = 2.0 Hz), 3.82 (t, 1H, C CH, J = 2.0 Hz) ppm; 13C NMR
∫
=
(100.62 MHz, DMSO-d6): d 219 (C O), 148.00 (C3-pz), 139.07
(C5-pz), 108.66 (C4-pz), 82.56 (Cq-tpm), 79.87 (C C), 78.18 (C C),
∫
∫
∫
64.99 (OCH2–Cq-tpm), 58.63 (OCH2–C C) ppm.
[Mn(CO)3(tpm-L2)]PF6 (11). Manganese pentacarbonyl bro-
mide (126 mg, 0.47 mmol) und tpm-L2 (10) (234 mg, 0.47 mmol)
were dissolved in anhydrous acetone (15 mL) and heated to
reflux for 4.5 h under a nitrogen atmosphere with exclusion of
light. After cooling to RT, the solvent was removed in vacuo and
the yellow residue redissolved in methanol. Upon addition of
an aqueous solution of sodium hexafluorophosphate (87.0 mg,
0.47 mmol), a bright yellow precipitate formed which was
dissolved again by heating and finally crystallized at +4 ◦C.
Yield: 65% (240 mg, 0.31 mmol). Elemental analysis (%): calc.
for C29H34F6MnN7O7P·3.5H2O: C 41.05, H 4.04, N 11.55, found:
˚
using a Dynamax RP analytical column (C18 microsorb 60 A,
diameter 10 mm, 250 mm length) with a mixture of water and
acetonitrile containing 0.1% v/v trifluoroacetic acid as the eluent,
using a linear gradient of 5–95% acetonitrile over 30 min at a
flow rate of 1 mL min-1. The myoglobin assay was carried out in a
quartz cuvette (d = 1 cm) with a Jasco V-670 UV/Vis spectrometer
as described below.
C 40.85, H 3.01, N 11.14; MS (ESI+, acetone): m/z 640 [M - PF6]+;
-1
=
=
IR (ATR, cm ): 2049 (s) n(fac-C O), 2019 (s) n(fac-C O), 1934
Microwave-assisted solid-phase peptide synthesis
=
=
=
(s) n(fac-C O), 1738 (s) n(C O, ester), 1661 (s) n(C O, amide);
1H NMR (400.13 MHz, DMSO-d6): d 8.90 (d, 1H, NH, 3JCH,NH
=
All peptides were prepared on a CEM Liberty peptide synthesizer
on a 0.25 mmol scale, using the Fmoc-strategy and a pre-
loaded Fmoc-Leu–Wang resin as solid support under microwave-
irradiation in all steps. Deprotection of the Fmoc-protected
amino acids was done with a solution of 20% piperidine in
dimethylformamide. For each coupling step, four equivalents of
amino acid (0.2 M in DMF) and coupling reagent (HOBT/TBTU,
0.45 M in DMF) were used. Diisopropylethylamine (DIPEA)
served as the activator base. After the last coupling step, the resin
was taken out of the microwave reactor and cleavage of the peptide
from the solid support was performed in a filter syringe at room
temperature, using a solution of TFA–TIS–H2O (90 : 5 : 5).
The peptide was then isolated by precipitation with cold diethyl
ether (-20 ◦C) and repeated cycles of washing, centrifugation and
decanting. The remaining residue was dissolved in a acetonitrile–
water mixture and lyophilized, yielding the peptides as essentially
white solids. Different from the above procedure, the final coupling
of azidoacetic acid (15) was performed in a filter syringe at RT
using a solution of azidoacetic acid–HOBT–TBTU (each 0.4 M) in
DMF with DIPEA as the activator base (0.3 M) over 90 min. After
excessive washing with DMF and dichloromethane, the peptide
was cleaved from the resin as described above.
3
7.7 Hz); 8.68 (d, br, 3H, H(3-pz), J = 2.5 Hz), 8.62 (d, br, 3H,
3
H(5-pz), J = 2.5 Hz), 8.14 (s, br, 2H, H-Ar2,6), 7.96 (s, br, 2H,
3
H-Ar3,5), 6.77 (pseudo t, 3H, H(4-pz), J = 2.5 Hz), 5.66 (s, 2H,
OCH2C(pz)3), 4.53 (ddd, 1H, H-a, 3JCH,NH = 7.7 Hz, 3Ja,b = 8.8 Hz,
3
∫
Ja,b¢ = 5.8 Hz), 5.13 (s, 2H, C C–CH2), 3.60 (s, 3H, OCH3), 3.07
(dd, 1H, H-b, 3Ja,b = 8.8 Hz, 2Jb,b¢ = 13.8 Hz), 2.95 (dd, 1H, H-b¢,
3Ja,b¢ = 5.8 Hz, 2Jb,b¢ = 13.8 Hz), 2.74 (s, 3H, NHCO–CH3) ppm; 13C
=
=
NMR (100.62 MHz, DMSO-d6): d 219.29 (C O), 171.44 (C O,
=
ester), 165.41 (C O, amide), 141.80 (C3-pz), 136.65 (C1-Ar), 129.01
(C2,6-Ar), 128.26 (C5-pz), 126.61 (C3,5-Ar), 126.19 (C4-Ar), 108.62 (C4-pz),
∫
∫
82.62 (Cq-tpm), 65.53 (Ar–C C), 64.07 (Ar–C C), 53.74 (OCH2-
∫
(pz)3), 51.92 (C C–CH2–O), 51.28 (Ca), 36.70 (OCH3), 35.71 (Cb),
30.71 (NHCO–CH3) ppm.
[Mn(CO)3(tpm-L3)]PF6 (17). N-Azidoacetyl-DL-phenylala-
ninemethyl ester (16) (100 mg, 0.38 mmol) and [Mn(tpm-
L1)(CO)3]PF6 (5) (213 mg, 0.38 mmol) were suspended in a
1 : 1 mixture of tert-butanol and water (12 mL). Then, sodium
ascorbate (7.5 mg, 0.038 mmol, 10 mol%) and copper(II) sulfate
pentahydrate (1 mg, 0.0038 mmol, 1 mol%) were added and
the suspension stirred at room temperature under a nitrogen
atmosphere for 48 h. The clear solution was poured into ice-water
(50 mL) and the light yellow precipitate formed was separated by
centrifugation, dissolved in acetonitrile and lyophilized, yielding
a yellow hygroscopic solid. Yield: 55% (172 mg, 0.21 mmol).
Elemental analysis (%): calc. for C29H28F6MnN10O7P: C 42.04,
H 3.41, N 16.91, found: C 42.41, H 3.77, N 16.74; MS (ESI+,
CH3OH): m/z 683 [M - PF6]+; IR (ATR, cm-1): 3403 (w), 3153
Synthetic procedures
[Mn(CO)3(tpm-L1)]PF6 (5). Tris-2,2,2-(pyrazol-1-yl)ethoxy-
propargyl ether (4) (1.00 g, 3.50 mmol) and manganese pentacar-
bonyl bromide (0.94 g, 3.40 mmol) were dissolved in anhydrous
acetone (30 mL) and heated to reflux for 6 h under a nitrogen
atmosphere with exclusion of light. The yellow precipitate was
filtered off, re-dissolved in methanol and an aqueous solution of
potassium hexafluorophosphate (571 mg, 3.40 mmol) was added.
The yellow precipitate was filtered off and dried under vacuum.
Yield: 54% (1.03 g, 1.82 mmol). Elemental analysis (%): calc. for
C17H14F6MnN6O4P: C 36.06, H 3.49, N 14.84, found: C 35.71,
=
=
(w), 2957 (w), 2049 (s) n(fac-C O), 1938 (s) n(fac-C O), 1740 (m)
1
=
=
n(C O, ester), 1661 (m) n(C O, amide); H NMR (400.13 MHz,
DMSO-d6): d 8.69 (s, br, 3H, H(3-pz)), 8.64 (s, br, 3H, H(5-pz)),
3
8.32 (d, 1H, H-Ar4, J = 5.7 Hz), 8.29 (s, 1H, triazolyl-H), 7.47
3
(d, br, 2H, H-Ar(2,6)(3,5), J = 5.7 Hz), 7.26 (d, br, 2H, H-Ar(2,6)(3,5)
,
3J = 5.7 Hz), 6.78 (s, br, 3H, H(4-pz)), 5.69 (s, 2H, CH2), 4.94 (s,
2H, CH2), 4.46 (s, br, 1H, H-a), 3.58 (s, 2H, CH2), 3.02 (m, br,
1H, H-b), 2.88 (m, br, 1H, H-b¢), 1.76 (s, 3H, OCH3) ppm; 13C
H 3.42, N 14.69; MS (ESI+, CH3OH): m/z 421 [M - PF6]+; IR
-1
∫
=
(ATR, cm ): 3306 (w) n(CC–H), 2130 (w) n(C C), 2050 (s) n(fac-
NMR (100.62 MHz, DMSO-d6): d 219.03 (C O), 147.68 (C3-pz),
1
=
=
C O), 1951 (s) n(fac-C O); H NMR (400.13 MHz, DMSO-d6):
138.43 (C5-pz), 131.17, 129.09, 119.19, 108.80 (C4-pz), 108.34, 87.70,
4296 | Dalton Trans., 2009, 4292–4298
This journal is
The Royal Society of Chemistry 2009
©