Selective treatment of cancer: Synthesis, biological evaluation and structural elucidation of novel analogues of the antibiotic CC-1065 and the duocarmycins

Article abstract of DOI:10.1002/chem.200700113

Novel diastereomerically pure β-D-galactosidic prodrugs (+)-12a-e of the cytotoxic antibiotics CC-1065 and the duocarmycins were prepared for an antibody directed enzyme prodrug therapy (ADEPT) using 4 as a substrate via a radical cyclization to give rac-

Full text of DOI:10.1002/chem.200700113

FULL PAPER
DOI: 10.1002/chem.200700113
4396
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Chem. Eur. J. 2007, 13, 4396 –4409

FULL PAPER
Selective Treatment of Cancer: Synthesis, Biological Evaluation and
Structural Elucidation of Novel Analogues of the Antibiotic CC-1065 and the
Duocarmycins
Lutz F. Tietze,*[a] Felix Major,[a] Ingrid Schuberth,[a] Dirk A. Spiegl,[a] Birgit Krewer,[a]
[c]
Katja Maksimenka,[b] Gerhard Bringmann,[b] and JçrgMagull
Dedicated to Professor Burchard Franck on the occasion of his 80th birthday
Abstract: Novel diastereomerically
pure b-d-galactosidic prodrugs (+)-
12a–e of the cytotoxic antibiotics CC-
1065 and the duocarmycins were pre-
pared for an antibody directed enzyme
prodrug therapy (ADEPT) using 4 as a
substrate via a radical cyclization to
give rac-5 and rac-6 followed by a
chromatographic resolution of the
enantiomers of rac-5, glycosidation and
linkage to the DNA-binding units 10a–
e. These only slightly toxic compounds
can be toxified enzymatically by an an-
tibody–b-d-galactosidase conjugate at
the surface of malignant cells to give
the cytotoxic drugs, which then alkylate
DNA. The new prodrugs were tested in
in vitro cytotoxicity assays showing ex-
cellent QIC50 values of 4800 and 4300
for (+)-12a and (+)-12b, respectively.
The absolute configuration of precur-
sor (+)-5 was determined by compari-
son of the experimental CD spectrum
with the theoretically predicted CD
spectra and by X-ray structure analysis.
Keywords:
antitumor agents
·
cancer therapy · circular dichroism ·
prodrugs
Introduction
cells by employing an antibody–enzyme conjugate. It is a
prerequisite that the prodrug has a relatively low toxicity
whereas the corresponding drug selectively formed from the
prodrug at the cancer cells should have a very high cytotox-
icity. For a successful application of ADEPT in the treat-
ment of cancer we propose the following requirements: The
The antibody directed enzyme prodrug therapy
(ADEPT)[1,2] is a promising concept for a selective treat-
ment of cancer, in which a prodrug is enzymatically convert-
ed into a cytotoxic compound at the surface of malignant
1
drug should have a high cytotoxicity with an IC50 value of
less than 10 nm and the QIC50 should be above 1000 [QIC50 =
IC50 (prodrug)/IC50 (prodrug + corresponding enzyme)].[3]
A class of compounds which is very appropriate for
ADEPT is characterized by the antibiotic CC-1065 (1) and
the duocarmycins such as 2, which belong to the most
potent antitumor agents discovered so far.[4] CC-1065 (1)
and duocarmycin SA (2) specifically bind to double-strand-
ed DNA within AT-rich minor grooves and alkylate N-3 of
particular adenine moieties.[5] CC-1065 (1) itself, however, is
less suitable due to a delayed lethal liver toxicity,[6] whereas
other compounds of this type such as 2 having a similar cy-
totoxicity do not show this effect.
[a] Prof. Dr. Dr. h.c. L. F. Tietze, Dr. F. Major, Dr. I. Schuberth,
Dipl.-Chem. D. A. Spiegl, Dipl.-Chem. B. Krewer
Institut für Organische und Biomolekulare Chemie
Georg-August-Universität Gçttingen
Tammannstrasse 2, 37077 Gçttingen (Germany)
Fax : (+49)(0)551-399476
E-mail: ltietze@gwdg.de
[b] Dipl.-Chem. K. Maksimenka, Prof. Dr. Dr. h.c. G. Bringmann
Institut für Organische Chemie
Julius-Maximilians-Universität Würzburg
Am Hubland, 97074 Würzburg (Germany)
[c] Prof. Dr. J. Magull
Institut für Anorganische Chemie
Georg-August-Universität Gçttingen
Tammannstrasse 4, 37077 Gçttingen (Germany)
Some time ago we have demonstrated that the formation
of the spirocyclopropane moiety as the pharmacophoric
group of CC-1065 (1) and duocarmycin SA (2) from a corre-
Supporting information for this article is available on the WWW
under http://www.chemeurj.org/ or from the author: CD spectra of
(+)-5 in different solvents (Figure S1), defined dihedral angles and
heats of formation of the 16 minimum conformers of (1S,10R)-5
(Table S1), CD spectra predicted by OM2 and TDDFT calculations.
1
IC50 refers to the drug concentration required for 50% inhibition of
target cells.
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L. F. Tietze et al.
sponding seco-compound can be halted by transforming its
phenolic hydroxyl group into a glycoside as shown in 3
(Scheme 1).[7] Such a derivative can be hydrolyzed enzymati-
cally using a glycohydrolase which liberates the drug. In this
way, glycosidic seco-CBI-Q 3 and similar compounds bear-
ing a bisindolyl carboxylic acid moiety as a DNA-binding
subunit were developed by us for ADEPT.[8,9] However,
major drawbacks in their application are their poor water
solubility and difficulties in the preparation of sufficient
amounts of especially 3 due to low yields in the last steps of
the synthesis. Moreover, the compounds have been em-
ployed so far as diastereomeric mixtures since the chiral
core was used as a racemic mixture in the glycosidation.
iodonaphthylamine 4[11] with (E/Z)-1,3-dichloro-2-butene
and subsequent radical cyclization employing nontoxic tris-
trimethylsilylsilane (TTMSS) and AIBN led to N-Boc-
methyl-seco-CBI 5/6 (Scheme 2). In the ring formation, two
stereogenic centers are formed, and since a facial differen-
tiation does not occur, a 1:1 mixture of the diastereomers 5
and 6 was obtained as a racemic mixture. In vitro cytotoxici-
ty tests showed that the diastereomers possess a consider-
able difference in their biological activity. Thus, compounds
with a syn-orientation of the two hydrogens at the two ste-
reogenic centers such as 6 (1S/R,10S/R) are not suitable for
the development of prodrugs due to a rather low cytotoxici-
ty of the corresponding seco-drugs, whereas compounds
with the anti-orientation such as 5 (1S/R,10R/S) show appro-
priate properties.[8] The syn- and anti-diastereomers could be
easily separated by chromatography on silica gel. For the
synthesis of enantiopure (+)-5 the use of classical resolution
methods was investigated. However, differential crystalliza-
tion of diastereomeric salts with enantiopure acids such as
tartaric acid or camphorsulfonic acid and preparation of dia-
stereomeric compounds using enantiopure reagents were
not successful due to the low stability of the corresponding
free amine of rac-5. Therefore, we employed an effective
chromatographic resolution on a semipreparative Chiralpak
IA column, which allowed the separation of 50 mg racemic
5 per injection within 10 min. By this method (+)-5 and (ꢀ)-
5 could be obtained with ee values of 99.9%. Finally, the
benzylic ether moiety in (+)-5 was cleaved by catalytic
transfer hydrogenation[12] to provide phenol (+)-7 as a pre-
cursor of diastereopure glycosidic prodrugs.
Scheme 1. Structures of (+)-CC-1065 (1), (+)-duocarmycin SA (2), and
glycosidic prodrug 3.
Here we describe a new type of prodrugs which are easily
accessible, have a much better water solubility, can be pre-
pared in diastereomerically pure form, and moreover show
higher QIC50 values, which make these prodrugs superior to
all other compounds described so far for the use in ADEPT.
A short communication of parts of this work has recently
been published.[10]
Scheme 2. a) NaH, DMF, RT, 1 h, then (E/Z)-1,3-dichloro-2-butene,
DMF, RT, 2 h, 98%; b) TTMSS, AIBN, toluene, 808C, 5 h, rac-5: 44%,
rac-6: 42%; c) resolution of rac-5: Chiralpak IA (250”20 mm, particle
size: 5 mm), CH2Cl2/n-heptane 4:1, flow: 18 mLminꢀ1, a=2.05, (+)-5:
99.9% ee, (ꢀ)-5: 99.9% ee; d) Pd/C/NH4HCO2, THF, 408C, 15 min,
93%; e) 4m HCl/EtOAc, RT, 3 h, then 3,5-dibromobenzoic acid,
EDC·HCl, DMF, RT, 19 h, 63%.
Results and Discussion
Synthesis and chromatographic resolution of the N-Boc-
methyl-seco-CBI compound 5: N-Alkylation of the known
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Analogues of the Antibiotic CC-1065 and Duocarmycins
FULL PAPER
Determination of the absolute configuration of (+)-5 and
(ꢀ)-5: The absolute configurations of the two enantiomers
of 5 were independently determined by quantum chemical
circular dichroism (CD) computations[13–15] and X-ray struc-
ture analysis. For the prediction of a reliable theoretical CD
spectrum, in principle all possible conformational species
that may influence the overall CD behavior had to be taken
into consideration. For this purpose, two different ap-
proaches were applied: a comprehensive conformational
analysis and, taking into account the high flexibility of the
molecule, molecular dynamics (MD) simulations. Both cal-
culations were arbitrarily started with the (1S,10R)-enantio-
mer of 5. The conformational analysis was performed on the
semiempirical AM1 level,[16] revealing the existence of 15
conformers with energies not higher than 3 kcalmolꢀ1 above
the global minimum (Figure 1 and Table S1 in the Support-
ing Information). In the case of the molecular dynamics sim-
ulation,[17] 1000 structures were extracted in 0.5 ps intervals
over a total MD time of 500 ps.
5a) and, in a second approach, by a hydroxy group (i.e.,
structure 5b). The geometries thus obtained were submitted
to CD calculations at the semiempirical CNDO/S[18] level.
For the 16 conformers obtained from the conformational
analysis, CD calculations were also performed by the
OM2[20] approach (Figure S2a, Supporting Information). De-
spite their identical absolute configuration, those two single
conformers (Figure 2) that differed only in the position of
the “freely” rotating phenyl ring, provided almost opposite
CD spectra, once again demonstrating the necessity of con-
sidering all sufficiently populated conformational species
and not only the global minimum structure.
Figure 2. Two single conformers, A and B, of (1S,10R)-5 that differ only
in the orientation of the phenyl ring, and the corresponding CNDO/S
based CD spectra.
The overall calculated CD curves were obtained by
means of Boltzmann weighting of the single CD spectra,
that is, according to the heat of formation of the respective
conformer obtained during the conformational analysis (Fig-
ure 3a), while for the MD simulated structures the respec-
tive single spectra were just arithmetically added up (Fig-
ure 3b). Reflection of these calculated CD spectra at the
zero line generated the theoretical spectra predicted for the
enantiomeric compounds (1R,10S)-5a and (1R,10S)-5b. The
comparison of the calculated CD spectra of both, (1S,10R)-
5a and (1S,10R)-5b, with the measured CD curve of (+)-5
showed a good agreement in the decisive region of 200–
290 nm, while the broad doubled band between 300 and
380 nm was not entirely reproduced (Figure 3a, left). On
the other hand, the respective MD based CD spectra reflect-
ed this region correctly (Figure 3b, left). Expectedly, the CD
curves predicted for (1R,10S)-5a and (1R,10S)-5b behaved
almost oppositely (Figure 3a, b, right). By this way, the ab-
solute configuration of (+)-5 was assigned to be (1S,10R).
Unexpectedly, CD calculations at the TDDFT/B3LYP/
TZVP[21–23] level gave less clear results (Figure S2b, Support-
ing Information).
Figure 1. Results of the AM1 based conformational analysis of (1S,10R)-
5; a) global minimum geometry; b) set of 15 conformers within a range
of 3 kcalmolꢀ1 above that global minimum.
Since halogen atoms are not parametrized within the semi-
empirical CNDO/S,[18] INDO/S,[19] and OM2 methods,[20] the
chlorine atom in 5 had to be replaced by other appropriate
groups. On the one hand an ethyl group as the closest no
lone-pair electrons containing substituent and on the other
hand a hydroxy group, which does possess an electron pair,
were chosen. Based on the geometries found during the con-
formational analysis and the MD simulation, the chlorine
atom was replaced by an ethyl substituent (to give structure
These results were confirmed independently by structure
elucidation using anomalous X-ray scattering of (+)-
(1S,10R)-8, which was obtained from (+)-(1S,10R)-5 by
acid-catalyzed amine deprotection and subsequent 1-(3-di-
methylaminopropyl)-3-ethylcarbodiimide
hydrochloride
(EDC·HCl) mediated coupling with 3,5-dibromobenzoic
acid.[24]
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L. F. Tietze et al.
Figure 3. Determination of the absolute configuration of (+)-5 as
(1S,10R) by comparison of the experimental CD curve (in acetonitrile)
with the theoretically predicted CD spectra (CNDO/S) of 5a and 5b; a)
according to the conformational analysis; b) by using the MD method.
Scheme 3. Synthesis of b-d-galactosidic prodrugs (+)-(1S,10R)-12a–e: a)
9, BF3·OEt2, CH2Cl2, 4 Š MS, ꢀ108C ! RT, 9 h; b) 10a–c, EDC·HCl,
DMF, RT, 20–22 h; 10d,e, EDC·HCl, DMF, RT, 20–22 h, then PtO2·H2O/
H2, EtOH, RT, 5–16 h; c) NaOMe/MeOH, RT, 20–120 min; yields from
(+)-7: (+)-12a: 46%, (+)-12b: 43%, (+)-12c: 39%, (+)-12d: 29%, (+)-
12e: 36%.
Synthesis of b-d-galactosidic prodrugs (+)-(1S,10R)-12a–e:
As already mentioned, it has been shown for CC-1065 (1)
that the type of the DNA-binding unit connected to the
pharmacophoric group has a considerable influence on the
toxicity of the drug and on the water solubility. Moreover,
we expected that this unit might also affect the QIC50
values. We therefore prepared five novel glycosidic prodrugs
12a–e which differ in the side chain of the indole carboxylic
acids 10a–e.[27,28]
tocol described above provided exclusively the N-oxide 11 f
and a mixture of 11e and g, respectively. However, reduc-
tion of the N-oxides using hydrogen in the presence of cata-
lytic amounts of PtO2·H2O followed by solvolysis of the ace-
tate groups yielded the desired b-d-galactosidic compounds
(+)-(1S,10R)-12d in 29% and (+)-(1S,10R)-12e in 36%
yield over four steps.
For the synthesis of the b-d-galactosides (+)-(1S,10R)-
12a–c, phenol (+)-(1S,10R)-7 was treated with the trichloro-
acetimidate 9 of tetraacetylgalactose in the presence of
BF3·OEt2 using the Schmidt procedure (Scheme 3).[29] Since
we were able to remove the protecting group at the nitrogen
Synthesis of seco-drughydrochlorides ( +)-(1S,10R)-14a–e:
For a comparison of the cytotoxicity of the b-d-galactosidic
prodrugs (+)-(1S,10R)-12a–e in the presence of the enzyme
b-d-galactosidase with the seco-drugs (+)-(1S,10R)-14a–e
containing a free phenolic hydroxy group, we synthesized
the corresponding unstable indoline hydrochloride salt,
which was subsequently reacted in an EDC-mediated cou-
pling with indole carboxylic acid hydrochlorides 10a–e to
give (+)-(1S,10R)-13a–e (Scheme 4). These compounds
were converted into their hydrochlorides using again 4m
HCl/EtOAc. The debenzylation was then achieved under
mild conditions using 10% Pd/C in the presence of ammoni-
simultaneously during the glycosidation,
a subsequent
EDC·HCl-mediated addition of indole carboxylic acid hy-
drochlorides 10a–c was performed providing 11a–c. Finally,
the acetate groups in 11a–c were removed by solvolysis with
sodium methoxide in methanol to give the desired b-d-ga-
lactoside prodrugs (+)-(1S,10R)-12a–c in 39–46% overall
yield based on (+)-(1S,10R)-7. Surprisingly, the use of the
indole carboxylic acid hydrochlorides 10d and e in the pro-
4400
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Analogues of the Antibiotic CC-1065 and Duocarmycins
FULL PAPER
Table 1. In vitro cytotoxicity of b-d-galactosidic prodrugs (+)-12a–e in
the presence or absence of b-d-galactosidase and of the seco-drug hydro-
chlorides (+)-14a–e against human bronchial carcinoma cells (A549).[a]
Compound
Addition of
IC50 [nm]
QIC50
b-d-galactosidase
(+)-12a
(+)-12a
(+)-14a
(+)-12b
(+)-12b
(+)-14b
(+)-12c
(+)-12c
(+)-14c
(+)-12d
(+)-12d
(+)-14d
(+)-12e
(+)-12e
(+)-14e
ꢀ
+
ꢀ
ꢀ
+
ꢀ
ꢀ
+
ꢀ
ꢀ
+
ꢀ
ꢀ
+
ꢀ
3.6”103
0.75
4800
0.75
9.4”102
0.22
4300
1300
600
0.20
7.7”103
5.9
3.8
1.5”103
2.5
3.7
8.3”102
0.75
1100
0.80
[a] Cells were exposed to various concentrations of the test substance for
24 h at 378C; after 12 days of incubation the clone formation was com-
pared with an untreated control assay and the relative clone forming rate
was determined. b-d-galactosidase: Escherichia coli, 4 UmLꢀ1
.
The cytotoxicities found for all seco-drug hydrochlorides
(+)-14a–e were similar to those observed for the corre-
sponding glycosidic prodrugs (+)-12a–e in the presence of
the enzyme b-d-galactosidase, which indicates that the
enzyme is not deactivated in the hydrolytic process. Except
for (+)-12d, all prodrugs fortunately met the requirements
for a successful use in ADEPT (QIC50 > 1000; IC50 (pro-
drug + enzyme) < 10 nm). Prodrug (+)-12a is the most
potent one with an excellent QIC50 of 4800 and a high cyto-
toxicity of the corresponding seco-drug (+)-14a (IC50 =
0.75 nm) as well as of the prodrug in presence of b-d-galac-
tosidase (IC50 =0.75 nm). Compound (+)-12b bearing an ad-
ditional methoxy substituent at C-6 of the DNA-binding
subunit is four times more toxic than (+)-12a but has a
slightly lower QIC50 of 4300. By contrast, prodrug (+)-12c,
which has no longer an N,N-dimethylaminoethoxy but an
N,N-dimethylglycine substituent at C-5 of the indole moiety,
shows a twofold decreased cytotoxicity compared with (+)-
12a, also a decreased cytotoxicity of the corresponding
seco-drug and a moderate QIC50 of 1300. Surprisingly, pro-
drug (+)-12e with a sterically demanding N-methylpiperi-
dinyl-methoxy substituent is four times more toxic than (+)-
12a. In addition, (+)-12e shows the same cytotoxicity in the
presence of the enzyme as it was found for (+)-12a in the
presence of the enzyme resulting in a moderate QIC50 of
1100. Finally, prodrug (+)-12d bearing a morpholinoethoxy
substituent, which is also sterically demanding, is two times
more toxic than (+)-12a whereas prodrug (+)-12d in the
presence of the enzyme shows a three times lower cytotoxic-
ity. This is the reason for the low QIC50 of 600, which is in
our opinion not sufficient for an application of (+)-12d in
ADEPT.
Scheme 4. Synthesis of seco-drug hydrochlorides (+)-(1S,10R)-14a–e: a)
4m HCl/EtOAc, RT, 3–3.5 h; b) 10a–e, EDC·HCl, DMF, RT, 19–24 h; c)
4m HCl/EtOAc, RT, 2 h, then Pd/C/NH4HCO2, THF, 408C, 20–120 min;
yields from (+)-5: (+)-14a: 65%, (+)-14b: 57%, (+)-14c: 66%, (+)-
14d: 69%, (+)-14e: 62%.
um formate[12] to yield the seco-drug hydrochlorides (+)-
14a–e in a yield of 57–69% based on (+)-5. Direct debenzy-
lation of (+)-13a to the corresponding phenol, by contrast,
led to decomposition, which is probably due to deprotona-
tion of the phenol moiety by the tertiary amine followed by
cyclization and other unwanted side reactions. It is also
noteworthy that the direct glycosidation of the seco-drug hy-
drochlorides, for example, (+)-14a using the Schmidt proce-
dure was not successful. In contrast to the reaction of the
galactoside of (+)-7 with 10d and e, the formation of N-
oxides was not observed in the synthesis of 14d and e.
In vitro cytotoxicity tests: The in vitro cytotoxicity assays
were carried out in triplicate with coherent cells of the
human bronchial carcinoma cell line A549 in six multiwell
plates with concentrations of 102, 103, 104, and 105 cells per
cavity. Incubation with various concentrations of seco-drug
hydrochlorides (+)-14a–e and b-d-galactosidic prodrugs
(+)-12a–e in the absence or in the presence of b-d-galacto-
sidase was performed in ultraculture medium (Table 1). An
important criterion is the comparison of the IC50 value of
the seco-drug hydrochloride and the IC50 value of the galac-
tosidic prodrug in the presence of b-d-galactosidase. If the
IC50 values are similar one can assume that the seco-drug is
formed from the prodrug and that the activity of the
enzyme is not affected by the liberation of the seco-drug.
As expected, the different QIC50 values of our b-d-galac-
tosidic prodrugs (+)-12a–e and the different cytotoxicity of
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L. F. Tietze et al.
spectra were recorded with Mercury-200, VXR-200, Unity 300, Inova
500, Unity Inova-600 (Varian) or AMX 300 (Bruker) spectrometers.
Chemical shifts are reported in d (ppm) with tetramethylsilane (TMS) as
internal standard. Multiplicities of 13C NMR peaks were determined with
the APT pulse sequence. Mass spectra were measured with a Finnigan
MAT 95, TSQ 7000 and LCQ instrument. HRMS was performed with a
7 T FTICR-MS APEX IV (Bruker). The following abbreviations are
used in the text: EtOAc=ethyl acetate, PE=petroleum ether (b.p. 35–
608C).
the seco-drug hydrochlorides (+)-14a–e are due to the
nature of the DNA-binding indole subunit. In this context,
Boger et al. have reported previously that substituents at C-
5 of the DNA binding subunit have a pronounced effect on
the rate and efficiency of DNA alkylation and the resulting
biological potency of CC-1065 analogues, which is largely in-
sensitive to the electronic character of the substituent but is
sensitive to its size, rigid length, and shape.[30] This would ex-
plain why the different seco-drugs 14a–e have such a differ-
ent cytotoxicity, but it does not explain the different QIC50
values ranging from 4800 to 600. Further work will thus con-
centrate on this aspect; we intend to investigate the mode of
action of these compounds employing our newly developed
ESI-HRMS based method[31] for the determination of the
DNA alkylation activity and selectivity.
CD measurements: CD spectra of (+)-(1S,10R)-5 were obtained on a J-
715 spectrometer (Jasco) in a 0.2 mm quartz cuvette at room temperature
within the range of 200–400 nm.
Computational methods: The conformational analysis of 5 was performed
on
a Linux AMD MP 2800+ workstation using the semiempirical
AM1[16] method as implemented in the program package Gaussian 98.[32]
The molecular dynamics (MD) simulation was performed at a virtual
temperature of 500 K using the TRIPOS[17] force field, as implemented in
the molecular modeling package SYBYL. The overall simulation time
was 500 ps.
The single structures of 5a and b were created by the replacement of the
chlorine atom of 5 by an ethyl and by a hydroxy group, respectively,
using the program package Molden 4.2.[33] The wave functions for the cal-
culation of the rotational strengths for the electronic transitions from the
ground state to the excited states were obtained by CNDO/S-CI[18] and
OM2-CI[20] computations with a CI expansion including 576 and 900
singly occupied configurations, respectively, and the ground state deter-
minant. These calculations were carried out on a Linux Pentium III
workstation by the use of the BDZDO/MCDSPD[34] and MNDO99[35]
program packages. The calculated rotational strengths were transformed
into De values and superimposed with a Gaussian band shape function.
The CD spectra thus obtained were then UV-corrected[36] by 15 nm in
the case of the conformational analysis, and by 5 nm for the MD based
approach. Time-dependent DFT calculations of 35 excited states being
lowest in energy were performed using the B3LYP[21,22] functional and a
TZVP[23] basis set within the TURBOMOLE[37] suite of programs.
Conclusion
Ten enantio- and diastereopure (+)-anti-methyl-seco-CBI
compounds [(+)-12a–e and (+)-14a–e] bearing the DNA-
binding subunits 10a–e were prepared. In vitro cytotoxicity
tests of these compounds against the human bronchial carci-
noma cell line A549 revealed that all prodrugs except (+)-
12d meet the requirements for a successful use in ADEPT.
Moreover, b-d-galactosidic prodrugs (+)-12a and (+)-12b
show excellent QIC50 values of 4800 and 4300, respectively;
thus, these substances are superior to all compounds de-
scribed so far for the use in ADEPT. Besides this, the cyto-
toxicities found for all seco-drug hydrochlorides (+)-14a–e
were similar to those observed for the corresponding glyco-
sidic prodrugs (+)-12a–e in the presence of the enzyme b-d-
galactosidase, which indicates that the enzyme is not deacti-
vated in the hydrolytic process. In addition, an advantage of
all new compounds is their improved water solubility due to
their solubilizing tertiary amino functionality as part of their
DNA-binding subunit. Furthermore, resolution of precursor
rac-5 and determination of the absolute configuration of
(+)-(1S,10R)-5 by comparison of the experimental CD
curve with the theoretically predicted CD spectra were re-
ported. These results were confirmed independently by an
X-ray structure analysis using anomalous scattering of the
3,5-dibromobenzoic acid amide (+)-(1S,10R)-8.
rac-(1S,10R)-5-Benzyloxy-3-(tert-butyloxycarbonyl)-1-(10-chloroethyl)-
1,2-dihydro-3H-benz[e]indole (rac-5): A solution of amine
4 (9.51 g,
20.0 mmol) in DMF (100 mL) was added to a suspension of NaH (60%
in oil, 2.00 g, 50.0 mmol) in DMF (150 mL) and the resulting mixture was
stirred for 1 h at room temperature. Then, (E/Z)-1,3-dichloro-2-butene
(4.31 mL, 5.00 g, 38.4 mmol) was added and the reaction mixture stirred
for further 2 h followed by addition of a saturated aqueous solution of
NH4Cl (200 mL) and extraction with EtOAc (3”250 mL). The combined
organic layers were washed with water (3”250 mL) and brine (250 mL),
dried (MgSO4) and the solvent was removed in vacuo. The resulting
crude product was purified by column chromatography on silica gel (PE/
EtOAc 20:1) to provide (E/Z)-2-amino-4-benzyloxy-N-(tert-butyloxycar-
bonyl)-N-(3-chloro-2-butenyl)-1-iodonaphthalene as a white solid (11.0 g,
19.5 mmol, 98%). Rf =0.33, 0.40 (PE/EtOAc 10:1); 1H NMR (200 MHz,
CDCl3): d=1.32/1.58 (s, 9H, CCATHREU(NG CH3)3), 1.81/2.03 (s, 3H, 4’-CH3), 3.77–
4.31 (m, 1H, 1’-Ha), 4.41–4.64 (m, 1H, 1’-Hb), 5.25 (brs, 2H, OCH2Ph),
5.65–5.90 (m, 1H, 2’-H), 6.65–6.88 (m, 1H, 3-H), 7.34–7.68 (m, 7H, 6-H,
7-H, 5”Ph-H), 8.15–8.37 ppm (m, 2H, 5-H, 8-H); 13C NMR (50 MHz,
CDCl3): d=20.9/26.2 (C-4’), 28.3/28.5 (C
ACHTRE(UNG CH3)3), 46.5/47.8 (C-1’), 70.4/
70.5 (OCH2), 80.5 (C(CH3)3), 94.9/95.2 (C-1), 107.1/107.8 (C-3), 121.6/
AHCTREUNG
Experimental Section
122.8 (C-2’), 122.5 (2 signals) (C-5), 125.4 (C-4a), 126.2, 126.3, 127.3, (C-
6, C-8), 128.1, 128.2, 128.5 (2 signals), 128.7 (2 signals) (5”Bn-CH),
132.7/132.8 (C-7), 134.0/135.3 (C-3’), 135.3 (C-8a), 136.3/136.4 (Bn-C),
142.5/143.1 (C-2), 153.7/153.9 (C=O), 155.2/155.3 ppm (C-4); MS (DCI,
200 eV): m/z (%): 581.5 (100) [M ++NH4]; HRMS (ESI): m/z: calcd for
C26H27ClINO3Na: 586.0622; found: 586.0616 [M ++Na].
General: All reactions were performed under argon in flame-dried flasks.
All solvents were dried and distilled prior to use by usual laboratory
methods. All reagents obtained from commercial sources were used with-
out further purification. Thin-layer chromatography (TLC) was per-
formed on precoated silica gel SIL G/UV254 plates (Macherey–Nagel)
and silica gel 60 (0.032–0.063 mm, Merck) was used for column chroma-
tography. Phosphomolybdic acid in MeOH (PMA) or vanillin in metha-
nolic sulphuric acid were used as staining reagents for TLC. UV spectra
were taken in CH3CN or MeOH with a Perkin–Elmer Lambda 2 spec-
trometer. IR spectra were recorded as KBr pellets or as films with a
Bruker IFS 25 spectrometer. Optical rotations were measured with a
A thoroughly degassed solution of (E/Z)-2-amino-4-benzyloxy-N-(tert-
butyloxycarbonyl)-N-(3-chloro-2-butenyl)-1-iodonaphthalene
(4.00 g,
7.09 mmol) in toluene (120 mL) was treated with tris(trimethylsilyl)silane
(2.41 mL, 7.80 mmol) and AIBN (291 mg, 1.77 mmol). Then, the stirred
reaction mixture was heated to 808C using a preheated oil bath and stir-
ring was continued for 5 h. After cooling to room temperature the sol-
vent was removed in vacuo and the two diastereomers were separated by
Perkin–Elmer 241 polarimeter in the solvent indicated. H and 13C NMR
1
4402
www.chemeurj.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 4396 –4409

Analogues of the Antibiotic CC-1065 and Duocarmycins
FULL PAPER
column chromatography on silica gel (PE/EtOAc 40:1 ! 10:1) to give
the desired diastereomer rac-5 (1.37 g, 3.12 mmol, 44%) as a white solid.
Rf =0.32 (PE/EtOAc 10:1); 1H NMR (200 MHz, CDCl3): d=1.58–1.65
1H, 2-Ha), 4.34 (dd, J=11.5, 9.2 Hz, 1H, 2-Hb), 4.75 (dq, J=6.7, 3.0 Hz,
1H, 10-H), 5.19 (brs, 2H, OCH2), 7.31–7.62 (m, 8H, 4’-H, 7-H, 8-H, 5”
Bn-H), 7.79 (d, J=1.8 Hz, 2H, 2’-H, 6’-H), 7.92 (d, J=8.3 Hz, 1H, 9-H),
8.00 (m, 1H, 4-H), 8.23 ppm (d, J=8.3 Hz, 1H, 6-H); 13C NMR (75 MHz,
[D6]DMSO, 1008C): d=22.9 (C-11), 45.1 (C-1), 52.0 (C-2), 60.6 (C-10),
69.8 (OCH2), 97.7 (C-5a*), 118.0, 122.3, 122.7, 123.5 (C-4’, C-6, C-7, C-9,
C-9a, C-9b*), 126.8, 127.1, 127.4, 128.0 (C-8, 5”Bn-CH), 128.3 (C-2’, C-
6’), 129.5 (C-3’, C-5’), 134.7 (C-4), 136.2 (Bn-C), 139.9, 140.3 (C-1’, C-3a),
154.2 (C-5), 163.8 ppm (C=O); IR (KBr): n˜ =3064, 2918, 1642, 1579,
1551, 1454, 1404 cmꢀ1; UV (CH3CN): lmax (lg e)=208.5 (4.750), 252.0
(4.584), 324.5 nm (4.113); MS (EI, 70 eV): m/z (%): 599 (14) [M +], 536
(33) [M +ꢀCHClCH3]; HRMS (EI): m/z: calcd for C28H22Br2ClNO2:
596.9706; found: 596.9706.
(m, 12H, CACHTREUNG(CH3)3, 11-H3), 3.86 (ddd, J=9.4, 2”3.1 Hz, 1H, 1-H), 4.07
(m, 1H, 2-Ha), 4.34 (m, 1H, 2-Hb), 4.60 (m, 1H, 10-H), 5.26 (s, 2H,
OCH2Ph), 7.27–7.69 (m, 8H, 7-H, 8-H, 9-H, 5”Ph-H), 7.87 (brs, 1H, 4-
H), 8.30 ppm (d, J=8.0 Hz, 1H, 6-H); 13C NMR (50 MHz, CDCl3): d=
23.7 (C-11), 28.5 (C
ACHTREUNG(CH3)3), 46.0 (C-1), 50.7 (C-2), 60.2 (C-10), 70.2
(OCH2), 80.9 (C(CH3)3), 96.3 (C-4), 115.2 (C-9b), 122.4 (C-5a), 122.1,
ACHTREUNG
122.9, 123.6 (C-6, C-7, C-9), 127.3 (C-8), 127.6, 127.9, 128.5 (5”Bn-CH),
130.4 (C-9a), 136.9 (Bn-C), 142.0 (C-3a), 152.4 (C=O), 155.8 ppm (C-5);
IR (KBr): n˜ =3445, 2977, 2928, 1698, 1626, 1580, 1455, 1410, 1367, 1338,
1272, 1147, 910, 846, 751 cmꢀ1; UV (CH3CN): lmax (lg e)=207.0 (4.442),
217.5 (4.388), 255.0 (4.845), 302.5 (3.966), 314.0 (4.051), 341.0 nm (3.537);
MS (DCI, 200 eV): m/z (%): 455.5 (100) [M ++NH4], 438.5 (47) [M +
+H]; HRMS (ESI): m/z: calcd for C26H28ClNO3Na: 460.1655; found:
460.1650 [M ++Na].
General procedure 1
Preparation of b-d-galactosidic prodrugs [(+)-(1S,10R)-12a–c]: A solu-
tion of phenol (+)-(1S,10R)-7 in dry CH2Cl2 (c=0.02m) was treated with
molecular sieves (4 Š; 0.8 g) and stirred for 30 min at room temperature.
Then trichloroacetimidate 9 (1.03 equiv) was added, the reaction mixture
cooled to ꢀ108C and a solution of BF3·OEt2 (0.5 equiv) in dry CH2Cl2
(c=0.10m) added dropwise. Stirring was continued for 4 h at this temper-
ature followed by dropwise addition of additional BF3·OEt2 (3.0 equiv) in
dry CH2Cl2 (c=0.66m). The reaction mixture was allowed to warm to
room temperature and was stirred for further 5 h. The solution was sepa-
rated from the molecular sieves under argon by transfer cannula and the
molecular sieves were washed with CH2Cl2 (2”10 mL). The combined
solutions were concentrated and the residue was thoroughly dried in
vacuo.
Chromatographic resolution of rac-5:
A solution of rac-5 (1.10 g,
2.51 mmol) in a 1:1 mixture of n-heptane and CH2Cl2 (22 mL) was sepa-
rated consecutively (injection volume: 1 mL) by semipreparative HPLC
(Chiralpak IA, 250”20 mm, particle size: 5 mm; n-heptane/CH2Cl2 4:1;
flow: 18 mLminꢀ1; UV detector: l=250 nm) to provide (+)-(1S,10R)-5
(tR =5.2 min) and (ꢀ)-(1R,10S)-5 (tR =7.1 min). The optical purity was
determined by analytical HPLC (Chiralcel OD, 250”4.6 mm, particle
size: 10 mm; n-hexane/iPrOH 99:1; flow: 0.8 mLminꢀ1; UV detector: l=
254 nm): (+)-(1S,10R)-5: 99.9% ee (tR =13.6 min); [a]2D0 = +28.0 (c=0.8
in CHCl3); (ꢀ)-(1R,10S)-5: 99.9% ee (tR =17.4 min); [a]2D0 = ꢀ27.0 (c=
0.8 in CHCl3).
The residue was dissolved in dry DMF (c=0.02m) and the solution
cooled to 08C. EDC·HCl (3.0 equiv) and indole 10a–c (1.5 equiv) were
added and the reaction mixture was allowed to warm to room tempera-
ture. After stirring for 20–22 h at this temperature, the solution was dilut-
ed with EtOAc (25 mL), water (25 mL) and a saturated aqueous solution
of NaHCO3 (25 mL). The mixture was extracted with EtOAc (4”50 mL),
the combined organic fractions were washed with brine (4”100 mL),
dried (MgSO4) and the solvent was removed in vacuo. Purification by
column chromatography on silica gel (CH2Cl2/MeOH) provided tetraace-
tylglycosides (+)-11a–c.
(+)-{(1S,10R)-3-(tert-Butyloxycarbonyl)-1-(10-chloroethyl)-5-hydroxy-
1,2-dihydro-3H-benz[e]indole} [(+)-(1S,10R)-7]: (+)-(1S,10R)-5 (197 mg,
450 mmol) was dissolved in freshly distilled THF (15 mL) and the result-
ing solution was warmed to 408C. Then, Pd/C (10%, 96 mg) was added
under stirring and
a 25% (w/w) aqueous solution of NH4HCO2
(0.96 mL) was added dropwise. After stirring for 15 min at 408C, the
solid was removed by filtration through Celite which was washed thor-
oughly with acetone (250 mL). The concentrated filtrate was purified by
column chromatography (PE/EtOAc 30:1 ! 10:1) to give (+)-7 (146 mg,
420 mmol, 93%) as a white solid. Rf =0.30 (PE/EtOAc 5:1); [a]D20
=
A solution of (+)-11a–c in dry MeOH (c=0.02m) was treated with a
5.4m solution of NaOMe in MeOH (2.0 equiv) at 08C and the reaction
mixture was allowed to warm to room temperature. After stirring for 30–
120 min at this temperature, the solution was diluted with MeOH (2 mL)
and water (2 mL) and the mixture was adjusted to neutral pH by addition
of ion-exchange resin (Amberlite-IR 120). The solution was separated
from the ion-exchange resin by filtration and the ion-exchange resin was
washed with MeOH (10 mL). The combined solutions were concentrated
and the residue was purified by column chromatography (CH2Cl2/
MeOH) to provide galactosides (+)-12a–c.
+11.4 (c=0.5 in CHCl3); 1H NMR (300 MHz, CDCl3): d=1.55–1.64 (m,
12H, C(CH3)3, 11-H3), 3.80 (m, 1H, 1-H), 4.00 (m, 1H, 2-Ha), 4.30 (m,
ACHTREUNG
1H, 2-Hb), 4.54 (m, 1H, 10-H), 7.30 (m, 1H, 7-H), 7.44 (m, 1H, 8-H),
7.59 (d, J=8.3 Hz, 1H, 9-H), 7.70–7.92 (2”brs, 2H, 4-H, OH), 8.12 ppm
(d, J=8.3 Hz, 1H, 6-H); 13C NMR (75 MHz, CDCl3): d=23.8 (C-11),
28.5 (CACHTREUNG(CH3)3), 46.1 (C-1), 51.2 (C-2), 60.3 (C-10), 81.5 (CACHTRE(UGN CH3)3), 99.1
(C-4), 114.9 (C-9b), 121.7 (C-5a), 122.1, 122.6, 123.6 (C-6, C-7, C-9),
127.1 (C-8), 130.5 (C-9a), 141.4 (C-3a), 152.8 (C=O), 153.9 ppm (C-5); IR
(KBr): n˜ =3380, 2976, 1686, 1629, 1585, 1412, 1342, 1249, 1147, 1044, 911,
853, 751 cmꢀ1; UV (CH3CN): lmax (lg e)=207.5 (4.245), 219.0 (4.216),
255.5 (4.869), 304.5 (3.908), 315.5 (3.973), 342.5 nm (3.485); MS (ESI):
m/z (%): 717 (12) [2M ++Na], 370 (21) [M ++Na]; HRMS (ESI): m/z:
calcd for C19H22ClNO3H: 348.1366; found: 348.1361 [M ++H].
(+)-{[(1S,10R)-1-(10-Chloroethyl)-3-[(5-(2-N,N-dimethylaminoethoxy)-
indol-2-yl)carbonyl]-1,2-dihydro-3H-benz[e]indol-5-yl] b-d-galactopyra-
noside} [(+)-(1S,10R)-12a]: According to GP 1 phenol (+)-7 (130 mg,
374 mmol) in dry CH2Cl2 (16 mL) was glycosylated with
9 (190 mg,
386 mmol) and BF3·OEt2 (24 mL, 189 mmol) in dry CH2Cl2 (1.9 mL). Addi-
tional BF3·OEt2 (142 mL, 1.12 mmol) in dry CH2Cl2 (1.7 mL) was added
for N-Boc deprotection and the residue was then treated with EDC·HCl
(215 mg, 1.12 mmol) and indole 10a (160 mg, 561 mmol) in DMF (17 mL)
for 20 h to give (+)-11a (168 mg, 208 mmol, 56%) after purification by
column chromatography (CH2Cl2/MeOH 10:1) as a brown solid. Rf =0.43
(CH2Cl2/MeOH 10:1); HRMS (ESI): m/z: calcd for C41H46ClN3O12H:
808.2843; found: 808.2843 [M ++H].
(+)-{(1S,10R)-5-Benzyloxy-1-(10-chloroethyl)-3-[(3,5-dibromophenyl)car-
bonyl]-1,2-dihydro-3H-benz[e]indole} [(+)-8]: Benzyl ether (+)-5
(70.0 mg, 160 mmol) was treated with 4m HCl/EtOAc (10 mL) and stirred
at room temperature for 3 h. The resulting solution was concentrated in
vacuo and the residue was thoroughly dried under vacuum. Then, the res-
idue was dissolved in dry DMF (10 mL) and the solution cooled to 08C.
EDC·HCl (92.0 mg, 480 mmol) and 3,5-dibromobenzoic acid (58.0 mg,
208 mmol) were added and the reaction mixture was allowed to warm to
room temperature. After stirring for 19 h at this temperature, the solu-
tion was diluted with water (25 mL) and a saturated aqueous solution of
NaHCO3 (10 mL). The mixture was extracted with EtOAc (3”50 mL),
the combined organic fractions were washed with brine (4”100 mL),
dried (MgSO4) and the solvent was removed in vacuo. Purification by
column chromatography on silica gel (PE/EtOAc 5:1) provided (+)-8 as
pale yellow needles (60 mg, 100 mmol, 63%). Rf =0.35 (PE/EtOAc 5:1);
Solvolysis of (+)-11a (164 mg, 203 mmol) in MeOH (9 mL) was per-
formed in 2 h with
a 5.4m solution of NaOMe in MeOH (75 mL,
406 mmol). Purification by column chromatography on silica gel (CH2Cl2/
MeOH 1:1) provided (+)-12a (106 mg, 166 mmol, 82%) as a pale yellow
solid. Rf =0.26 (CH2Cl2/MeOH 1:1); [a]2D0 = +10.0 (c=0.2 in DMSO);
1H NMR (600 MHz, [D6]DMSO): d=1.65 (d, J=6.6 Hz, 3H, 11-H3), 2.24
(s, 6H, NMe2), 2.66 (t, J=5.9 Hz, 2H, 2’’-H2), 3.44–3.61 (m, 3H, 3’’’-H,
5’’’-H, 6’’’-Ha), 3.63–3.72 (m, 1-H, 6’’’-Hb), 3.76–3.86 (m, 2H, 2’’’-H, 4’’’-
H), 4.07 (t, J=5.9 Hz, 2H, 1’’-H2), 4.24 (m, 1H, 1-H), 4.58–4.71 (m, 3H,
[a]2D0
=
+13.7 (c=0.35, CHCl3); 1H NMR (300 MHz, [D6]DMSO,
1008C): d=1.58 (d, J=6.7 Hz, 3H, 11-H3), 4.08 (m, 1H, 1-H), 4.15 (m,
Chem. Eur. J. 2007, 13, 4396 –4409
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
4403

L. F. Tietze et al.
2”OH, 2-Ha), 4.75 (m, 1H, 2-Hb), 4.82 (m, 1H, 10-H), 4.93 (m, 2H, 1’’’-
H, OH), 5.36 (brs, 1H, OH), 6.92 (dd, J=9.0, 2.2 Hz, 1H, 6’-H), 7.13–
7.19 (m, 2H, 3’-H, 4’-H), 7.37–7.46 (m, 2H, 7-H, 7’-H), 7.56 (m, 1H, 8-
H), 7.95 (d, J=8.4 Hz, 1H, 9-H), 8.23 (brs, 1H, 4-H), 8.36 (d, J=8.4 Hz,
1H, 6-H), 11.64 ppm (brs, 1H, NH); 13C NMR (150 MHz, [D6]DMSO):
d=23.4 (C-11), 45.5 (NMe2), 45.9 (C-1), 52.1 (C-2), 57.8 (C-2’’), 59.6 (C-
6’’’), 61.3 (C-10), 66.3 (C-1’’), 67.5, 70.4, 73.2, 75.2 (C-2’’’, C-3’’’, C-4’’’, C-
5’’’), 101.9 (C-4), 102.3 (C-1’’’), 103.2 (C-4’), 105.4 (C-3’), 113.1 (C-7’),
115.8 (C-6’), 118.8 (C-5a), 123.0, 123.4, 123.6 (C-6, C-7, C-9, C-9b), 127.2
(C-8), 127.5 (C-3a’), 129.4, 130.9, 131.7 (C-2’, C-7a’, C-9a), 142.0 (C-3a),
153.0 (C-5’), 153.6 (C-5), 160.1 ppm (C=O); IR (KBr): n˜ =3386, 1624,
1590, 1515, 1464, 1415, 1267, 1232, 1075, 760 cmꢀ1; UV (CH3CN): lmax (lg
e)=206.0 (4.644), 246.0 (4.322), 299.0 (4.487), 336.5 nm (4.424); MS
(ESI): m/z (%): 1280.9 (14) [2M ++H], 640.2 (100) [M ++H]; HRMS
(ESI): m/z: calcd for C33H38ClN3O8H: 640.2420; found: 640.2420 [M +
+H].
346 mmol). Purification by column chromatography on silica gel (CH2Cl2/
MeOH 7:1 ! 3:1) and washing with n-pentane (5”15 mL) provided (+)-
12c (93 mg, 142 mmol, 82%) as a yellow solid. Rf =0.32 (CH2Cl2/MeOH
5:1); [a]2D0
=
+19.1 (c=0.35 in DMSO); 1H NMR (600 MHz,
[D6]DMSO): d=1.65 (d, J=6.7 Hz, 3H, 11-H3), 2.31 (s, 6H, NMe2), 3.08
(s, 2H, 1’’-H2), 3.45–3.52 (m, 1H, 3’’’-H), 3.53–3.61 (m, 2H, 5’’’-H, 6’’’-Ha),
3.64–3.71 (m, 1H, 6’’’-Hb), 3.77–3.85 (m, 2H, 2’’’-H, 4’’’-H), 4.25 (m, 1H,
1-H), 4.55–4.66 (m, 3H, 2-Ha, 2”OH), 4.72–4.90 (m, 3H, 2-Hb, 10-H,
OH), 4.93 (m, 1H, 1’’’-H), 5.31 (brs, 1H, OH), 7.25 (brs, 1H, 3’-H), 7.37–
7.46 (m, 3H, 6’-H, 7’-H, 7-H), 7.57 (m, 1H, 8-H), 7.96 (d, J=8.4 Hz, 1H,
9-H), 8.13 (brs, 1H, 4’-H), 8.24 (brs, 1H, 4-H), 8.36 (d, J=8.6 Hz, 1H, 6-
H), 9.60 (s, 1H, NH), 11.70 ppm (s, 1H, NH); 13C NMR (150 MHz,
[D6]DMSO): d=23.4 (C-11), 45.3 (NMe2), 46.0 (C-1), 52.1 (C-2), 59.6 (C-
6’’’), 61.4 (C-10), 63.2 (C-1’’), 67.5 (C-4’’’), 70.6 (C-2’’’), 73.3 (C-3’’’), 75.2
(C-5’’’), 101.9 (C-4), 102.3 (C-1’’’), 105.8 (C-3’), 112.1 (C-4’), 112.2 (C-7’),
118.6 (C-6’), 119.0 (C-5a), 122.9, 123.1, 123.4, 123.7 (C-6, C-7, C-9, C-9b),
127.1 (C-3a’), 127.3 (C-8), 129.5, 131.1, 131.5, 133.3 (C-2’, C-5’, C-7a’, C-
9a), 142.0 (C-3a), 153.6 (C-5), 160.1 (C=O), 168.2 ppm (C=O); IR (KBr):
(+)-{[(1S,10R)-1-(10-Chloroethyl)-3-[(5-(2-N,N-dimethylaminoethoxy)-6-
methoxy-indol-2-yl)carbonyl]-1,2-dihydro-3H-benz[e]indol-5-yl] b-d-gal-
actopyranoside} [(+)-(1S,10R)-12b]: According to GP 1, phenol (+)-7
n˜ =3386, 2928, 1625, 1591, 1525, 1467, 1416, 1335, 1313, 1267, 1232 cmꢀ1
;
UV (CH3CN): lmax (lg e)=206.0 (4.505), 233.0 (4.470), 259.0 (4.488),
299.5 (4.424), 336.5 nm (4.382); MS (ESI): m/z (%): 653.2 (100) [M +
+H]; HRMS (ESI): m/z: calcd for C33H37ClN4O8H: 653.2378; found:
653.2373 [M ++H].
(106 mg, 305 mmol) in dry CH2Cl2 (14 mL) was glycosylated with
9
(155 mg, 314 mmol) and BF3·OEt2 (19 mL, 152 mmol) in dry CH2Cl2
(1.5 mL). Additional BF3·OEt2 (116 mL, 914 mmol) in dry CH2Cl2
(1.4 mL) was added for N-Boc deprotection and the residue was then
treated with EDC·HCl (175 mg, 914 mmol) and indole 10b (144 mg,
457 mmol) in DMF (14 mL) for 22 h to give (+)-11b (128 mg, 153 mmol,
50%) after purification by column chromatography (CH2Cl2/MeOH
10:1) as a brown solid. Rf =0.53 (CH2Cl2/MeOH 5:1); HRMS (ESI): m/z:
calcd for C42H48ClN3O13H: 838.2957; found: 838.2948 [M ++H].
(+)-{[(1S,10R)-1-(10-Chloroethyl)-3-[(5-(2-morpholin-4-yl-ethoxy)-indol-
2-yl)-carbonyl]1,2-dihydro-3H-benz[e]indol-5-yl] b-d-galactopyranoside}
[(+)-(1S,10R)-12d]: A solution of phenol (+)-7 (142 mg, 408 mmol) in
dry CH2Cl2 (18 mL) was treated with molecular sieves (4 Š; 0.8 g) and
stirred for 30 min at room temperature. After that, trichloroacetimidate 9
(207 mg, 420 mmol) was added and the reaction mixture was cooled to
ꢀ108C. Then, a solution of BF3·OEt2 (26 mL, 205 mmol) in dry CH2Cl2
(2.0 mL) was added dropwise and stirring was continued for 4 h at this
temperature. After dropwise addition of additional BF3·OEt2 (155 mL,
1.22 mmol) in dry CH2Cl2 (1.9 mL) the reaction mixture was allowed to
warm to room temperature and was stirred for further 5 h at room tem-
perature. The solution was separated from the molecular sieves under
argon by transfer cannula and the molecular sieves were washed with
CH2Cl2 (2”10 mL). The combined solutions were concentrated and the
residue was thoroughly dried in vacuo.
Solvolysis of (+)-11b (125 mg, 149 mmol) in MeOH (7 mL) was per-
formed in 30 min with a 5.4m solution of NaOMe in MeOH (55 mL,
298 mmol). Purification by column chromatography on silica gel (CH2Cl2/
MeOH 1:1) provided (+)-12b (86 mg, 128 mmol, 86%) as a pale yellow
solid. Rf =0.27 (CH2Cl2/MeOH 1:1, 1% NEt3); [a]2D0 = +2.0 (c=0.4 in
DMSO); 1H NMR (600 MHz, [D6]DMSO): d=1.66 (d, J=6.7 Hz, 3H,
11-H3), 2.25 (s, 6H, NMe2), 2.66 (t, J=6.0 Hz, 2H, 2’’-H2), 3.47 (m, 1H,
3’’’-H), 3.53–3.59 (m, 2H, 5’’’-H, 6’’’-Ha), 3.67 (m, 1-H, 6’’’-Hb), 3.77–3.83
(m, 5H, 2’’’-H, 4’’’-H, OCH3), 4.05 (t, J=6.0 Hz, 2H, 1’’-H2), 4.24 (m, 1H,
1-H), 4.54–4.77 (m, 4H, 2”OH, 2-H2), 4.82 (m, 1H, 10-H), 4.85–4.99 (m,
2H, 1’’’-H, OH), 5.32 (brs, 1H, OH), 6.98 (s, 1H, 7’-H), 7.14 (brs, 1H, 3’-
H), 7.18 (s, 1H, 4’-H), 7.42 (t, J=7.7 Hz, 1H, 7-H), 7.56 (t, J=7.6 Hz,
1H, 8-H), 7.95 (d, J=8.6 Hz, 1H, 9-H), 8.23 (brs, 1H, 4-H), 8.35 (d, J=
8.6 Hz, 1H, 6-H), 11.48 ppm (s, 1H, NH); 13C NMR (150 MHz,
[D6]DMSO): d=23.4 (C-11), 45.6 (NMe2), 46.0 (C-1), 52.0 (C-2), 55.6
(OCH3), 57.8 (C-2’’), 59.6 (C-6’’’), 61.3 (C-10), 67.2 (C-1’’), 67.5 (C-4’’’),
70.6 (C-2’’’), 73.3 (C-3’’’), 75.2 (C-5’’’), 94.7 (C-7’), 101.9 (C-4), 102.3 (C-
1’’’), 104.7 (C-4’), 106.1 (C-3’), 118.6 (C-5a), 120.3 (C-3a’), 122.8 (C-9),
122.9 (C-9b), 123.4 (C-6), 123.5 (C-7), 127.2 (C-8), 128.9, 129.5 (C-2’, C-
9a), 131.8 (C-7a’), 142.2 (C-3a), 144.6 (C-5’), 149.4 (C-6’), 153.6 (C-5),
160.1 ppm (C=O); IR (KBr): n˜ =3386, 2929, 1614, 1590, 1514, 1464, 1417,
1307, 1267, 1202, 1153, 1076 cmꢀ1; UV (CH3CN): lmax (lg e)=205.5
(4.666), 305.5 (4.265), 346.5 nm (4.539); MS (ESI): m/z (%): 670.3 (100)
[M ++H]; HRMS (ESI): m/z: calcd for C34H40ClN3O9H: 670.2531; found:
670.2526 [M ++H].
The residue was then dissolved in dry DMF (19 mL) and the solution
cooled to 08C. EDC·HCl (235 mg, 1.23 mmol) and indole 10d (200 mg,
612 mmol) were added and the reaction mixture was allowed to warm to
room temperature. After stirring for 20 h at this temperature, the solu-
tion was diluted with EtOAc (25 mL), water (25 mL) and a saturated
aqueous solution of NaHCO3 (25 mL). The mixture was extracted with
EtOAc (4”50 mL), the combined organic fractions were washed with
brine (4”100 mL), dried (MgSO4) and the solvent was removed in vacuo.
Purification by column chromatography on silica gel (CH2Cl2/MeOH
10:1) provided N-oxide (+)-11 f (142 mg, 164 mmol, 40%) as a pale
brown solid. Rf =0.15 (CH2Cl2/MeOH 10:1); HRMS (ESI): m/z: calcd for
C43H48ClN3O14H: 866.2903; found: 866.2898 [M ++H].
A solution of N-oxide (+)-11 f (67 mg, 77 mmol) was then dissolved in
dry EtOH (15 mL) and hydrogenated (balloon) over PtO2·H2O (81%,
6 mg) for 5 h at room temperature. The solid was removed by filtration
through Celite which was washed thoroughly with MeOH (50 mL) and
the concentrated filtrate was purified by column chromatography
(CH2Cl2/MeOH 10:1) to provide (+)-11d (53 mg, 62 mmol, 81%) as a
yellow solid. Rf =0.69 (CH2Cl2/MeOH 10:1); HRMS (ESI): m/z: calcd
for C43H48ClN3O13H: 850.2954; found: 850.2948 [M ++H].
(+)-{[(1S,10R)-1-(10-Chloroethyl)-3-[(5-(2-N,N-dimethylaminoacetylami-
no)-indol-2-yl)-carbonyl]-1,2-dihydro-3H-benz[e]indol-5-yl] b-d-galacto-
pyranoside} [(+)-(1S,10R)-12c]: According to GP
1 phenol (+)-7
(137 mg, 394 mmol) in dry CH2Cl2 (17 mL) was glycosylated with
9
(200 mg, 406 mmol) and BF3·OEt2 (25 mL, 197 mmol) in dry CH2Cl2
(1.9 mL). Additional BF3·OEt2 (150 mL, 1.18 mmol) in dry CH2Cl2
(1.8 mL) was added for N-Boc deprotection and the residue was then
treated with EDC·HCl (227 mg, 1.18 mmol) and indole 10c (176 mg,
591 mmol) in DMF (18 mL) for 21 h to give (+)-11c (155 mg, 189 mmol,
48%) after purification by column chromatography (CH2Cl2/MeOH
25:1) as a pale brown solid. Rf =0.57 (CH2Cl2/MeOH 10:1); HRMS
(ESI): m/z: calcd for C41H45ClN4O12H: 821.2801; found: 821.2795 [M +
+H].
Then, a solution of (+)-11d (51 mg, 60 mmol) in dry MeOH (6 mL) was
treated with a 5.4m solution of NaOMe in MeOH (22 mL, 120 mmol) at
08C and the reaction mixture was allowed to warm to room temperature.
After stirring for 20 min at this temperature, the solution was diluted
with MeOH (2 mL) and water (2 mL) and the mixture was adjusted to
neutral pH by addition of ion-exchange resin (Amberlite-IR 120). The
solution was separated from the ion-exchange resin by filtration and the
ion-exchange resin was washed with MeOH (10 mL). The combined solu-
tions were concentrated and the residue was purified by column chroma-
tography on silica gel (CH2Cl2/MeOH 10:1 ! 4:1). The obtained solid
Solvolysis of (+)-11c (142 mg, 173 mmol) in MeOH (6 mL) was per-
formed in 30 min with a 5.4m solution of NaOMe in MeOH (64 mL,
4404
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ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 4396 –4409

Analogues of the Antibiotic CC-1065 and Duocarmycins
FULL PAPER
was washed with n-pentane (4”15 mL) to provide galactoside (+)-12d
(37 mg, 54 mmol, 90%) as a yellow solid. Rf =0.19 (CH2Cl2/MeOH 10:1);
[a]2D0 = +4.4 (c=0.25 in DMSO); 1H NMR (600 MHz, [D6]DMSO): d=
1.65 (d, J=6.6 Hz, 3H, 11-H3), 2.48–2.52 (m, 4H, 3’’’-H2, 5’’’-H2), 2.73 (t,
J=5.8 Hz, 2H, 2’’-H2), 3.45–3.70 (m, 8H, 2’’’-H2, 6’’’-H2, 3’’’’-H, 5’’’’-H,
6’’’’-H2), 3.76–3.85 (m, 2H, 2’’’’-H, 4’’’’-H), 4.11 (t, J=5.8 Hz, 2H, 1’’-H2),
4.25 (m, 1H, 1-H), 4.52–4.65 (m, 3H, 2-Ha, 2”OH), 4.72–4.79 (m, 1H, 2-
Hb), 4.79–4.88 (m, 2H, 10-H, OH), 4.92 (m, 1H, 1’’’-H), 5.30 (brs, 1H,
OH), 6.92 (dd, J=8.9, 2.4 Hz, 1H, 6’-H), 7.14–7.20 (m, 2H, 3’-H, 4’-H),
7.40 (d, J=8.8 Hz, 1H, 7’-H), 7.43 (m, 1H, 7-H), 7.57 (m, 1H, 8-H), 7.96
(d, J=8.4 Hz, 1H, 9-H), 8.22 (brs, 1H, 4-H), 8.36 (d, J=8.5 Hz, 1H, 6-
H), 11.63 ppm (s, 1H, NH); 13C NMR (150 MHz, [D6]DMSO): d=23.4
(C-11), 46.0 (C-1), 52.1 (C-2), 53.6 (C-3’’’, C-5’’’), 57.1 (C-2’’), 59.5 (C-
6’’’’), 61.3 (C-10), 65.9 (C-1’’), 66.2 (C-2’’’, C-6’’’), 67.5 (C-4’’’’), 70.6 (C-
2’’’’), 73.2 (C-3’’’’), 75.1 (C-5’’’’), 101.9 (C-4), 102.3 (C-1’’’’), 103.4 (C-4’),
105.4 (C-3’), 113.2 (C-7’), 115.9 (C-6’), 118.9 (C-5a), 122.9, 123.0, 123.4,
123.7 (C-6, C-7, C-9, C-9b), 127.3, 127.5 (C-3a’, C-8), 129.5, 130.9, 131.7
(C-2’, C-7a’, C-9a), 142.0 (C-3a), 152.9 (C-5’), 153.6 (C-5), 160.1 ppm (C=
O); IR (KBr): n˜ =3385, 2924, 1624, 1590, 1516, 1462, 1416, 1290, 1267,
1233, 1071 cmꢀ1; UV (CH3CN): lmax (lg e)=205.5 (4.665), 246.5 (4.336),
299.0 (4.496), 336.0 nm (4.433); MS (ESI): m/z (%): 1385.1 (13) [2M +
+Na], 704.3 (100) [M ++Na], 682.3 (32) [M ++H]; HRMS (ESI): m/z:
calcd for C35H40ClN3O9H: 682.2531; found: 682.2526 [M ++H].
tions were concentrated and the residue was purified by column chroma-
tography on silica gel (CH2Cl2/MeOH 5:1). The obtained solid was
washed with n-pentane (5”15 mL) to provide galactoside (+)-12d
(53 mg, 78 mmol, 90%) as a pale yellow solid. Rf =0.22 (CH2Cl2/MeOH
5:1, 1% NEt3); [a]2D0 = +4.8 (c=0.25 in DMSO); 1H NMR (600 MHz,
[D6]DMSO, 1008C): d=1.40–1.50 (m, 2H, 3’’’-Hax, 5’’’-Hax), 1.65 (d, J=
6.7 Hz, 3H, 11-H3), 1.77–1.86 (m, 3H, 3’’’-Heq, 4’’’-H, 5’’’-Heq), 2.14 (m,
2H, 2’’’-Hax, 6’’’-Hax), 2.29 (s, 3H, NCH3), 2.87–2.93 (m, 2H, 2’’’-Heq, 6’’’-
H
eq), 3.15 (brs, H2O, 4”OH), 3.47–3.51, 3.52–3.56, 3.60–3.64, 3.68–3.73
(4”m, 4H, 3’’’’-H, 5’’’’-H, 6’’’’-H2), 3.81–3.92 (m, 4H, 1’’-H2, 2’’’’-H, 4’’’’-
H), 4.22 (m, 1H, 1-H), 4.63–4.73 (m, 2H, 2-H2), 4.81 (m, 1H, 10-H), 4.92
(d, J=7.6 Hz, 1H, 1’’’’-H), 6.93 (m, 1H, 6’-H), 7.09, 7.18 (2”brs, 2H, 3’-
H, 4’-H), 7.40–7.45 (m, 2H, 7-H, 7’-H), 7.56 (m, 1H, 8-H), 7.93 (d, J=
8.4 Hz, 1H, 9-H), 8.17 (brs, 1H, 4-H), 8.37 (d, J=8.6 Hz, 1H, 6-H),
11.31 ppm (s, 1H, NH); 13C NMR (150 MHz, [D6]DMSO): d=23.4 (C-
11), 28.1 (C-3’’’, C-5’’’), 34.5 (C-4’’’), 45.5 (NCH3), 46.0 (C-1), 52.1 (C-2),
54.5 (C-2’’’, C-6’’’), 59.6 (C-6’’’’), 61.3 (C-10), 67.5 (C-4’’’’), 70.6 (C-2’’’’),
72.5 (C-1’’), 73.3 (C-3’’’’), 75.2 (C-5’’’’), 101.9 (C-4), 102.3 (C-1’’’’), 103.4
(C-4’), 105.4 (C-3’), 113.2 (C-7’), 115.8 (C-6’), 118.9 (C-5a), 122.9, 123.0,
123.4, 123.7 (C-6, C-7, C-9, C-9b), 127.3, 127.5 (C-3a’, C-8), 129.5, 130.9,
131.7 (C-2’, C-7a’, C-9a), 142.0 (C-3a), 153.2 (C-5’), 153.6 (C-5),
160.2 ppm (C=O); IR (KBr): n˜ =3384, 2926, 1624, 1590, 1515, 1466, 1413,
1267, 1234 cmꢀ1; UV (CH3CN): lmax (lg e)=205.0 (4.618), 245.5 (4.270),
299.0 (4.434), 337.0 nm (4.368); MS (ESI): m/z (%): 702.3 (12) [M +
+Na], 680.3 (100) [M ++H]; HRMS (ESI): m/z: calcd for
C36H42ClN3O8H: 680.2739, found: 680.2733 [M ++H].
(+)-{[(1S,10R)-1-(10-Chloroethyl)-3-[(5-(1-methylpiperidin-4-yl-me-
thoxy)-indol-2-yl)-carbonyl]-1,2-dihydro-3-benz[e]indol-5-yl] b-d-galacto-
pyranoside} [(+)-(1S,10R)-12e]: A solution of phenol (+)-7 (134 mg,
385 mmol) in dry CH2Cl2 (17 mL) was treated with molecular sieves (4 Š;
0.8 g) and stirred for 30 min at room temperature. Trichloroacetimidate 9
(196 mg, 398 mmol) was added and the reaction mixture was cooled to
ꢀ108C. Then, a solution of BF3·OEt2 (25 mL, 197 mmol) in dry CH2Cl2
(1.9 mL) was added dropwise and stirring was continued for 4 h at this
temperature. After dropwise addition of additional BF3·OEt2 (146 mL,
1.15 mmol) in dry CH2Cl2 (1.8 mL) the reaction mixture was allowed to
warm to room temperature and was stirred for further 5 h at room tem-
perature. The solution was separated from the molecular sieves under
argon by transfer cannula and the molecular sieves were washed with
CH2Cl2 (2”10 mL). The combined solutions were concentrated and the
residue was thoroughly dried in vacuo.
General procedure 2
Preparation of (+)-(1S,10R)-13a–e: Benzyl ether (+)-5 was treated with
4m HCl/EtOAc (14 mL) and stirred at room temperature for 3–3.5 h.
The resulting solution was concentrated in vacuo and the residue was
thoroughly dried under vacuum. Then, the residue was dissolved in dry
DMF (10 mL) and the solution cooled to 08C. EDC·HCl (3.0 equiv) and
indole 10 (1.3 equiv) were added and the reaction mixture was allowed
to warm to room temperature. After stirring for 19–24 h at this tempera-
ture, the solution was diluted with EtOAc (50 mL), water (50 mL) and a
saturated aqueous solution of NaHCO3 (50 mL). The mixture was ex-
tracted with EtOAc (4”50 mL), the combined organic fractions were
washed with brine (4”100 mL), dried (MgSO4) and the solvent was re-
moved in vacuo. Purification by column chromatography on silica gel
(CH2Cl2/MeOH) provided (+)-13.
The residue was then dissolved in dry DMF (18 mL) and the solution
cooled to 08C. EDC·HCl (222 mg, 1.16 mmol) and indole 10e (188 mg,
579 mmol) were added and the reaction mixture was allowed to warm to
room temperature. After stirring for 20 h at this temperature, the solu-
tion was diluted with EtOAc (50 mL), water (50 mL) and a saturated
aqueous solution of NaHCO3 (50 mL). The mixture was extracted with
EtOAc (4”50 mL), the combined organic fractions were washed with
brine (4”100 mL), dried (MgSO4) and the solvent was removed in vacuo.
Purification by column chromatography on silica gel (CH2Cl2/MeOH
10:1 ! 5:1) provided (+)-11e (65 mg, 77 mmol, 20%) as a pale brown
solid and N-oxide (+)-11g (110 mg, 127 mmol, 33%) as a pale brown
solid. (+)-11e: Rf =0.27 (CH2Cl2/MeOH 10:1); HRMS (ESI): m/z: calcd
for C44H50ClN3O12H: 848.3161; found: 848.3156 [M ++H]; N-oxide (+)-
11g: Rf =0.13 (CH2Cl2/MeOH 10:1); HRMS (ESI): m/z: calcd for
C44H50ClN3O13H: 864.3110; found: 864.3105 [M ++H].
(+)-{(1S,10R)-5-Benzyloxy-1-(10-chloroethyl)-3-[(5-(2-N,N-dimethylami-
noethoxy)-indol-2-yl)-carbonyl]-1,2-dihydro-3H-benz[e]indole}
[(+)-
(1S,10R)-13a]: According to GP 2 benzyl ether (+)-5 (200 mg, 457 mmol)
was stirred in 4m HCl/EtOAc for 3.5 h at room temperature. The residue
was then treated with EDC·HCl (263 mg, 1.37 mmol) and indole 10a
(169 mg, 594 mmol) in DMF for 19 h at room temperature. Purification of
the crude product by column chromatography on silica gel (CH2Cl2/
MeOH 10:1) provided (+)-13a (196 mg, 345 mmol, 76%) as a pale brown
solid. Rf =0.40 (CH2Cl2/MeOH 10:1); [a]2D0 = +43.2 (c=0.5 in CHCl3);
1H NMR (300 MHz, CDCl3): d=1.62 (d, J=6.8 Hz, 3H, 11-H3), 2.37 (s,
6H, NMe2), 2.77 (t, J=5.7 Hz, 2H, 2’’-H2), 3.88–3.97 (m, 1H, 1-H), 4.10
(t, J=5.7 Hz, 2H, 1’’-H2), 4.46–4.60 (m, 2H, 2-Ha, 10-H), 4.84 (m, 1H, 2-
Hb), 5.24 (m, 2H, OCH2Ph), 6.94–7.04 (m, 2H, 3’-H, 6’-H), 7.12 (d, J=
2.2 Hz, 1H, 4’-H), 7.28–7.44, 7.45–7.55 (2”m, 8H, 7-H, 7’-H, 8-H, 5”Ph-
H), 7.67 (d, J=8.3 Hz, 1H, 9-H), 8.18 (brs, 1H, 4-H), 8.35 (d, J=8.3 Hz,
1H, 6-H), 9.81 ppm (brs, 1H, NH); 13C NMR (75 MHz, CDCl3): d=24.0
(C-11), 45.8 (NMe2), 47.5 (C-1), 53.6 (C-2), 58.3 (C-2’’), 59.9 (C-10), 66.5
(C-1’’), 70.3 (OCH2Ph), 98.2 (C-4), 103.5 (C-4’), 105.9 (C-3’), 112.7 (C-7’),
117.1, 117.2 (C-6’, C-5a), 122.5, 123.7, 123.7, 123.8 (C-6, C-7, C-9, C-9b),
127.4, 127.6, 127.9, 128.1, 128.5 (C-3a’, C-8, 5”Bn-CH), 130.0, 130.8,
131.4 (C-2’, C-7a’, C-9a), 136.7 (Bn-C), 142.4 (C-3a), 153.8 (C-5’), 155.6
(C-5), 160.5 ppm (C=O); IR (KBr): n˜ =3452, 2937, 1621, 1518, 1456,
1414 cmꢀ1; UV (CH3CN): lmax (lg e)=207.0 (4.826), 249.5 (4.434), 290.0
(4.446), 300.0 (4.606), 339.5 nm (4.519); MS (EI, 70 eV): m/z (%): 567.4
(11) [M +]; HRMS (EI): m/z: calcd for C34H34ClN3O3: 567.2289; found:
567.2289.
A solution of N-oxide (+)-11g (40 mg, 46 mmol) was then dissolved in
dry EtOH (6 mL) and hydrogenated (balloon) over PtO2·H2O (81%,
6 mg) for 16 h at room temperature. The solid was removed by filtration
through Celite which was washed thoroughly with MeOH (50 mL) and
the concentrated filtrate was purified by column chromatography
(CH2Cl2/MeOH 10:1) to provide (+)-11e (24 mg, 28 mmol, 61%) as a
yellow solid.
Then, a solution of (+)-11e (74 mg, 87 mmol) in dry MeOH (6 mL) was
treated with a 5.4m solution of NaOMe in MeOH (32 mL, 120 mmol) at
08C and the reaction mixture was allowed to warm to room temperature.
After stirring for 30 min at this temperature, the solution was diluted
with MeOH (2 mL) and water (2 mL) and the mixture was adjusted to
neutral pH by addition of ion-exchange resin (Amberlite-IR 120). The
solution was separated from the ion-exchange resin by filtration and the
ion-exchange resin was washed with MeOH (10 mL). The combined solu-
(+)-{(1S,10R)-5-Benzyloxy-1-(10-chloroethyl)-3-[(5-(2-N,N-dimethylami-
noethoxy)-6-methoxy-indol-2-yl)-carbonyl]-1,2-dihydro-3H-benz[e]in-
Chem. Eur. J. 2007, 13, 4396 –4409
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
4405

L. F. Tietze et al.
dole} [(+)-(1S,10R)-13b]: According to GP 2, benzyl ether (+)-5
(150 mg, 342 mmol) was stirred in 4m HCl/EtOAc for 3 h at room temper-
ature. The residue was then reacted with EDC·HCl (197 mg, 1.03 mmol)
and indole 10b (140 mg, 445 mmol) in DMF for 20 h at room tempera-
ture. Purification of the crude product by column chromatography on
silica gel (CH2Cl2/MeOH 10:1) provided (+)-13b (134 mg, 224 mmol,
54.1 (C-3’’’, C-5’’’), 57.8 (C-2’’), 59.9 (C-10), 66.3 (C-1’’), 66.9 (C-2’’’, C-
6’’’), 70.3 (OCH2Ph), 98.2 (C-4), 103.7 (C-4’), 105.8 (C-3’), 112.8 (C-7’),
117.0, 117.2 (C-6’, C-5a), 122.6 (C-9), 123.7, 123.7, 123.9 (C-6, C-7, C-9b),
127.4, 127.6, 127.9, 128.1, 128.5 (C-3a’, C-8, 5”Bn-CH), 130.0, 130.8,
131.5 (C-2’, C-7a’, C-9a), 136.7 (Bn-C), 142.4 (C-3a), 153.7 (C-5’), 155.6
(C-5), 160.5 ppm (C=O); IR (KBr): n˜ =3444, 2856, 1625, 1579, 1518,
1453, 1406, 1288, 1266 cmꢀ1; UV (CH3CN): lmax (lg e)=207.0 (4.783),
249.5 (4.391), 291.0 (4.405), 300.0 (4.566), 339.5 nm (4.477); MS (EI,
70 eV): m/z (%): 609.2 (1) [M +], 573.1 (3) [M +ꢀClꢀH], 100.0 (100)
66%) as a pale brown solid. Rf =0.46 (CH2Cl2/MeOH 5:1); [a]D20
=
+61.7 (c=0.3 in CHCl3); 1H NMR (300 MHz, CDCl3): d=1.60 (d, J=
6.7 Hz, 3H, 11-H3), 2.35 (s, 6H, NMe2), 2.80 (t, J=6.1 Hz, 2H, 2’’-H2),
3.28 (s, 3H, OCH3), 3.89–3.98 (m, 1H, 1-H), 4.09 (t, J=6.1 Hz, 2H, 1’’-
H2), 4.48–4.65 (m, 2H, 2-Ha, 10-H), 4.78–4.88 (m, 1H, 2-Hb), 5.26 (m,
2H, OCH2Ph), 6.71 (s, 1H, 7’-H), 6.98 (d, J=1.5 Hz, 1H, 3’-H), 7.07 (s,
1H, 4’-H), 7.22–7.43, 7.45–7.56 (2”m, 7H, 7-H, 8-H, 5”Ph-H), 7.67 (d,
J=8.2 Hz, 1H, 9-H), 8.35 (d, J=8.3 Hz, 1H, 6-H), 8.39 (brs, 1H, 4-H),
10.68 ppm (brs, 1H, NH); 13C NMR (75 MHz, CDCl3): d=23.8 (C-11),
45.8 (NMe2), 47.4 (C-1), 53.5 (C-2), 55.2 (OCH3), 58.0 (C-2’’), 59.7 (C-
10), 67.4 (C-1’’), 70.4 (OCH2Ph), 93.9 (C-7’), 98.5 (C-4), 104.8 (C-4’),
106.5 (C-3’), 117.3 (C-5a), 120.5 (C-3a’), 122.4 (C-9), 123.5, 123.6, 123.9
(C-6, C-7, C-9b), 127.5 (2 signals), 127.9, 128.5, (C-8, 5”Bn-CH), 128.7,
129.9, 132.3 (C-2’, C-7a’, C-9a), 136.6 (Bn-C), 142.7 (C-3a), 145.0 (C-5’),
150.4 (C-6’), 155.5 (C-5), 160.5 ppm (C=O); IR (KBr): n˜ =3256, 2938,
1625, 1585, 1514, 1459, 1405, 1306 cmꢀ1; UV (CH3CN): lmax (lg e)=206.5
(4.802), 245.0 (4.340), 307.0 (4.350), 349.0 nm (4.608); MS (ESI): m/z
(%): 1217.0 (19) [2M ++Na], 598.2 (100) [M ++H]; HRMS (ESI): m/z:
calcd for C35H36ClN3O4H: 598.2473; found: 598.2467 [M ++H].
(CH2)4O+]; HRMS (EI): m/z: calcd for C36H36ClN3O4: 609.2394;
[CH2ACHTREUNG
found: 609.2394.
(+)-{(1S,10R)-5-Benzyloxy-1-(10-chloroethyl)-3-[(5-(1-methylpiperidin-4-
yl-methoxy)-indol-2-yl)-carbonyl]-1,2-dihydro-3H-benz[e]indole}
[(+)-
(1S,10R)-13e]: According to GP 2, benzyl ether (+)-5 (150 mg,
342 mmol) was stirred in 4m HCl/EtOAc for 3.5 h at room temperature.
The residue was then treated with EDC·HCl (197 mg, 1.03 mmol) and
indole 10e (144 mg, 445 mmol) in DMF for 23 h at room temperature. Pu-
rification of the crude product by column chromatography on silica gel
(CH2Cl2/MeOH 10:1) provided (+)-13e (158 mg, 260 mmol, 76%) as a
beige solid. Rf =0.29 (CH2Cl2/MeOH 10:1); [a]2D0 = +36.3 (c=0.35 in
1
DMSO); H NMR (300 MHz, [D6]DMSO): d=1.32–1.51 (m, 2H, 3’’’-Hax,
5’’’-Hax), 1.63 (d, J=6.7 Hz, 3H, 11-H3), 1.71–1.88 (m, 3H, 3’’’-Heq, 4’’’-H,
5’’’-Heq), 2.07–2.22 (m, 2H, 2’’’-Hax, 6’’’-Hax), 2.30 (s, 3H, NCH3), 2.85–
3.01 (m, 2H, 2’’’-Heq, 6’’’-Heq), 3.85 (d, J=5.7 Hz, 2H, 1’’-H2), 4.16–4.27
(m, 1H, 1-H), 4.56–4.86 (m, 3H, 2-H2, 10-H), 5.30 (m, 2H, OCH2Ph),
6.93 (d, J=8.9, 2.3 Hz, 1H, 6’-H), 7.13–7.20 (m, 2H, 3’-H, 4’-H), 7.32–
7.49, 7.51–7.62 (2”m, 8H, 7-H, 7’-H, 8-H, 5”Ph-H), 7.96 (d, J=8.3 Hz,
1H, 9-H), 8.12 (brs, 1H, 4-H), 8.23 (d, J=8.4 Hz, 1H, 6-H), 11.62 ppm
(brs, 1H, NH); 13C NMR (75 MHz, [D6]DMSO): d=23.3 (C-11), 27.8 (C-
3’’’, C-5’’’), 34.2 (C-4’’’), 45.1 (NCH3), 45.9 (C-1), 52.0 (C-2), 54.3 (C-2’’’,
C-6’’’), 61.3 (C-10), 69.6 (OCH2Ph), 72.3 (C-1’’), 98.4 (C-4), 103.4 (C-4’),
105.3 (C-3’), 113.1 (C-7’), 115.8 (C-6’), 117.5 (C-5a), 122.6 (2 signals),
123.0, 123.7 (C-6, C-7, C-9, C-9b), 127.3, 127.4, 127.5, 127.8, 128.4 (C-3a’,
C-8, 5”Bn-CH), 129.6, 130.9, 131.6 (C-2’, C-7a’, C-9a), 136.8 (Bn-C),
142.1 (C-3a), 153.1 (C-5’), 154.2 (C-5), 160.1 ppm (C=O); UV (CH3CN):
lmax (lg e)=206.5 (4.768), 249.5 (4.369), 290.0 (4.385), 300.0 (4.546),
340.0 nm (4.457); IR (KBr): n˜ =3423, 2933, 2785, 1624, 1582, 1516, 1455,
1406, 1267, 1232 cmꢀ1; MS (EI, 70 eV): m/z (%): 607.0 (4) [M +], 571.0
(23) [M +ꢀClꢀH]; HRMS (ESI): m/z: calcd for C37H38ClN3O3H:
608.2680 [M ++H]; found: 608.2675.
(+)-{(1S,10R)-5-Benzyloxy-1-(10-chloroethyl)-3-[(5-(2-N,N-dimethylami-
noacetylamino)-indol-2-yl)-carbonyl]-1,2-dihydro-3H-benz[e]indole}
[(+)-(1S,10R)-13c]: According to GP 2, benzyl ether (+)-5 (150 mg,
342 mmol) was stirred in 4m HCl/EtOAc for 3.5 h at room temperature.
The residue was then reacted with EDC·HCl (197 mg, 1.03 mmol) and
indole 10c (133 mg, 445 mmol) in DMF for 24 h at room temperature. Pu-
rification of the crude product by column chromatography on silica gel
(CH2Cl2/MeOH 30:1) provided (+)-13c (155 mg, 267 mmol, 78%) as a
pale green foam. Rf =0.31 (CH2Cl2/MeOH 20:1); [a]2D0 = +66.0 (c=0.3
in CHCl3); 1H NMR (300 MHz, CDCl3): d=1.63 (d, J=6.8 Hz, 3H, 11-
H3), 2.39 (s, 6H, NMe2), 3.11 (s, 2H, 1’’-H2), 3.88–4.02 (m, 1H, 1-H),
4.47–4.63 (m, 2H, 2-Ha, 10-H), 4.84 (dd, J=10.8, 1.5 Hz, 1H, 2-Hb), 5.24
(m, 2H, OCH2Ph), 7.06 (d, J=1.4 Hz, 1H, 3’-H), 7.20 (dd, J=8.8, 1.9 Hz,
1H, 6’-H), 7.28–7.56 (m, 8H, 7-H, 7’-H, 8-H, 5”Ph-H), 7.68 (d, J=
8.2 Hz, 1H, 9-H), 8.13–8.28 (m, 2H, 4-H, 4’-H), 8.35 (d, J=8.3 Hz, 1H,
6-H), 9.11 (s, 1H, NH), 10.03 ppm (s, 1H, NH); 13C NMR (75 MHz,
CDCl3): d=23.9 (C-11), 46.0 (NMe2), 47.4 (C-1), 53.5 (C-2), 59.9 (C-10),
63.6 (C-1’’), 70.3 (OCH2Ph), 98.2 (C-4), 106.4 (C-3’), 112.1 (C-7’), 112.6
(C-4’), 117.3 (C-5a), 118.8 (C-6’), 122.5 (C-9), 123.7, 123.8, 123.9 (C-6, C-
7, C-9b), 127.4, 127.6, 127.9, 128.0, 128.5 (C-3a’, C-8, 5”Bn-CH), 129.9
(C-5’), 131.1, 131.2, 133.2 (C-2’, C-7a’, C-9a), 136.7 (Bn-C), 142.3 (C-3a),
155.5 (C-5), 160.4 (C=O), 168.6 ppm (C=O); IR (KBr): n˜ =3417, 3298,
2945, 1679, 1625, 1587, 1523, 1459, 1405, 1333, 1267 cmꢀ1; UV (CH3CN):
lmax (lg e)=207.5 (4.688), 233.5 (4.558), 260.0 (4.603), 301.0 (4.549),
339.5 nm (4.479); MS (EI, 70 eV): m/z (%): 580.0 (10) [M +], 544.0 (7)
[M +ꢀClꢀH]; HRMS (ESI): m/z: calcd for C34H33ClN4O3H: 580.2319;
found: 581.2314 [M ++H].
General procedure 3
Preparation of seco-drughydrochlorides
( +)-(1S,10R)-14a–e: Benzyl
ether (+)-13 was dissolved in 4m HCl/EtOAc (10 mL) and stirred for 2 h
at room temperature. The resulting solution was concentrated in vacuo
and the residue was thoroughly dried under vacuum. Then, the residue
was suspended in freshly distilled THF (8 mL) and 10% Pd/C and a 25%
(w/w) aqueous solution of NH4HCO2 were added. After stirring for 20–
120 min at 408C, the solid was removed by filtration through Celite
which was washed thoroughly with MeOH (150 mL). The concentrated
filtrate was purified by column chromatography (CH2Cl2/MeOH/conc.
HCl) to give seco-drug hydrochloride (+)-14.
(+)-{(1S,10R)-1-(10-Chloroethyl)-3-[(5-(2-N,N-dimethylaminoethoxy)-
indol-2-yl)-carbonyl]-5-hydroxy-1,2-dihydro-3H-benz[e]indole hydrochlo-
ride} [(+)-(1S,10)-14a]: According to GP 3, benzyl ether (+)-13a
(100 mg, 176 mmol) was stirred in 4m HCl/EtOAc. After that, a suspen-
sion of the residue was treated with Pd/C (10%, 38 mg) and a 25%
(w/w) aqueous solution of NH4HCO2 (0.38 mL), and the resulting mix-
ture was stirred for 2 h at 408C. Purification of the crude product by
column chromatography on silica gel (CH2Cl2/MeOH 5:1, 1% conc.
HCl) provided seco-drug hydrochloride (+)-14a (78 mg, 152 mmol, 86%)
as a green solid. Rf =0.43 (CH2Cl2/MeOH 5:1); [a]2D0 = +27.4 (c=0.5 in
MeOH); 1H NMR (300 MHz, [D6]DMSO): d=1.62 (d, J=6.6 Hz, 3H,
11-H3), 2.81 (s, 6H, NMe2), 3.47 (t, J=5.0 Hz, 2H, 2’’-H2), 4.16 (m, 1H,
1-H), 4.39 (t, J=5.0 Hz, 2H, 1’’-H2), 4.57 (m, 1H, 2-Ha), 4.66–4.81 (m,
2H, 2-Hb, 10-H), 7.00 (dd, J=8.9, 2.2 Hz, 1H, 6’-H), 7.16 (brs, 1H, 3’-H),
7.25 (d, J=2.0 Hz, 1H, 4’-H), 7.35 (t, J=7.6 Hz, 1H, 7-H), 7.45 (d, J=
8.9 Hz, 1H, 7’-H), 7.51 (t, J=7.5 Hz, 1H, 8-H), 7.88 (d, J=8.3 Hz, 1H, 9-
H), 7.97 (brs, 1H, 4-H), 8.14 (d, J=8.3 Hz, 1H, 6-H), 10.42 (s, 1H, OH),
(+)-{(1S,10R)-5-Benzyloxy-1-(10-chloroethyl)-3-[(5-(2-morpholin-4-yl-
ethoxy)-indol-2-yl)-carbonyl]-1,2-dihydro-3H-benz[e]indole}
[(+)-
(1S,10R)-13d]: According to GP 2, benzyl ether (+)-5 (150 mg,
342 mmol) was stirred in 4m HCl/EtOAc for 3 h at room temperature.
The residue was then reacted with EDC·HCl (197 mg, 1.03 mmol) and
indole 10d (146 mg, 445 mmol) in DMF for 21 h at room temperature. Pu-
rification of the crude product by column chromatography on silica gel
(CH2Cl2/MeOH 30:1) provided (+)-13d (156 mg, 256 mmol, 75%) as a
pale brown solid. Rf =0.25 (CH2Cl2/MeOH 30:1); [a]2D0 = +42.7 (c=0.3
in CHCl3); 1H NMR (300 MHz, CDCl3): d=1.62 (d, J=6.7 Hz, 3H, 11-
H3), 2.61 (m, 4H, 3’’’-H2, 5’’’-H2), 2.83 (t, J=5.8 Hz, 2H, 2’’-H2), 3.76 (m,
4H, 2’’’-H2, 6’’’-H2), 3.89–3.98 (m, 1H, 1-H), 4.15 (t, J=5.8 Hz, 2H, 1’’-
H2), 4.47–4.61 (m, 2H, 2-Ha, 10-H), 4.85 (m, 1H, 2-Hb), 5.25 (m, 2H,
OCH2Ph), 6.94–7.02 (m, 2H, 3’-H, 6’-H), 7.12 (d, J=2.3 Hz, 1H, 4’-H),
7.29–7.57 (m, 8H, 7-H, 7’-H, 8-H, 5”Ph-H), 7.68 (d, J=8.2 Hz, 1H, 9-H),
8.19 (brs, 1H, 4-H), 8.34 (d, J=8.2 Hz, 1H, 6-H), 9.88 ppm (brs, 1H,
NH); 13C NMR (75 MHz, CDCl3): d=24.0 (C-11), 47.5 (C-1), 53.6 (C-2),
4406
www.chemeurj.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 4396 –4409

Analogues of the Antibiotic CC-1065 and Duocarmycins
FULL PAPER
11.00 (brs, 1H, NH+), 11.65 ppm (brs, 1H, NH); 13C NMR (75 MHz,
[D6]DMSO): d=23.4 (C-11), 42.8 (NMe2), 45.9 (C-1), 52.1 (C-2), 55.4 (C-
2’’), 61.5 (C-10), 63.1 (C-1’’), 100.4 (C-4), 104.0 (C-4’), 105.2 (C-3’), 113.2
(C-7’), 115.6, 115.9 (C-6’, C-5a), 122.2, 122.9, 122.9, 123.1 (C-6, C-7, C-9,
C-9b), 127.0 (C-8), 127.4 (C-3a’), 129.8, 131.3, 131.9 (C-2’, C-7a’, C-9a),
142.1 (C-3a), 152.0 (C-5’), 153.9 (C-5), 159.8 ppm (C=O); IR (KBr): n˜ =
3318, 2227, 1614, 1589, 1516, 1417, 1236, 1023 cmꢀ1; UV (MeOH): lmax (lg
e)=207.5 (4.385), 248.5 (4.123), 303.0 (4.203), 337.5 nm (4.115); MS (EI,
70 eV): m/z (%): 441.3 (9) [M +ꢀ2HCl]; HRMS (ESI): m/z: calcd for
C27H29ClN3O3: 478.1892; found: 478.1892 [M +].
aqueous solution of NH4HCO2 (0.28 mL), and the resulting mixture was
stirred for 1 h at 408C. Purification of the crude product by column chro-
matography on silica gel (CH2Cl2/MeOH 5:1, 0.1% conc. HCl) provided
seco-drug hydrochloride (+)-14d (67 mg, 120 mmol, 82%) as a yellow
solid. Rf =0.30 (CH2Cl2/MeOH 10:1, 1% conc. HCl); [a]2D0 = +21.3 (c=
0.3 in DMSO); 1H NMR (300 MHz, [D6]DMSO): d=1.62 (d, J=6.5 Hz,
3H, 11-H3), 3.14–3.63 (m, 6H, 2’’-H2, 3’’’-H2, 5’’’-H2), 3.83–4.03 (m, 4H,
2’’’-H2, 6’’’-H2), 4.12–4.21 (m, 1H, 1-H), 4.41–4.64 (m, 3H, 1’’-H2, 2-Ha),
4.64–4.82 (m, 2H, 2-Hb, 10-H), 7.00 (dd, J=9.0, 1.8 Hz, 1H, 6’-H), 7.16
(brs, 1H, 3’-H), 7.25 (m, 1H, 4’-H), 7.35 (m, 1H, 7-H), 7.41–7.55 (m, 2H,
7’-H, 8-H), 7.88 (d, J=8.4 Hz, 1H, 9-H), 7.98 (brs, 1H, 4-H), 8.14 (d, J=
8.3 Hz, 1H, 6-H), 10.42 (s, 1H, OH), 11.65 (s, 1H, NH), 11.93 ppm (brs,
1H, NH+); 13C NMR (75 MHz, [D6]DMSO): d=23.4 (C-11), 45.9 (C-1),
51.6 (C-3’’’, C-5’’’), 52.1 (C-2), 54.9 (C-2’’), 61.5 (C-10), 62.8 (C-1’’), 63.0
(C-2’’’, C-6’’’), 100.4 (C-4), 104.0 (C-4’), 105.2 (C-3’), 113.2 (C-7’), 115.6,
115.9 (C-6’, C-5a), 122.2 (C-9b), 122.8, 122.9, 123.1 (C-6, C-7, C-9), 126.9
(C-8), 127.4 (C-3a’), 129.8, 131.3, 131.9 (C-2’, C-7a’, C-9a), 142.1 (C-3a),
151.9 (C-5’), 153.9 (C-5), 159.8 ppm (C=O); IR (KBr): n˜ =3406, 3204,
2594, 1629, 1610, 1589, 1518, 1445, 1415, 1236 cmꢀ1; UV (MeOH): lmax (lg
e)=206.5 (4.627), 249.0 (4.360), 303.0 (4.439), 336.0 nm (4.364); MS
(ESI): m/z (%): 520.1 (100) [M +ꢀCl]; HRMS (ESI): m/z: calcd for
C29H31ClN3O4: 520.2003; found: 520.1998 [M +].
(+)-{(1S,10R)-1-(10-Chloroethyl)-3-[(5-(2-N,N-dimethylaminoethoxy)-6-
methoxy-indol-2-yl)-carbonyl]-5-hydroxy-1,2-dihydro-3H-benz[e]indole
hydrochloride} [(+)-(1S,10R)-14b]: According to GP 3, benzyl ether (+)-
13b (80 mg, 134 mmol) was stirred in 4m HCl/EtOAc. After that, a sus-
pension of the residue was treated with Pd/C (10%, 29 mg) and a 25%
(w/w) aqueous solution of NH4HCO2 (0.29 mL), and the resulting mix-
ture was stirred for 20 min at 408C. Purification of the crude product by
column chromatography on silica gel (CH2Cl2/MeOH 5:1, 0.1% conc.
HCl) provided seco-drug hydrochloride (+)-14b (63 mg, 116 mmol, 86%)
as a green-yellow solid. Rf =0.35 (CH2Cl2/MeOH 5:1, 1% conc. HCl);
[a]2D0 = +29.3 (c=0.4 in MeOH); 1H NMR (300 MHz, [D6]DMSO): d=
1.63 (d, J=6.6 Hz, 3H, 11-H3), 2.89 (s, 6H, NMe2), 3.51 (m, 2H, 2’’-H2),
3.84 (s, 3H, OCH3), 4.11–4.20 (m, 1H, 1-H), 4.39 (m, 2H, 1’’-H2), 4.50–
4.82 (m, 3H, 2-H2, 10-H), 7.04 (s, 1H, 7’-H), 7.14 (d, J=1.5 Hz, 1H, 3’-
H), 7.30 (s, 1H, 4’-H), 7.34 (m, 1H, 7-H), 7.50 (m, 1H, 8-H), 7.87 (d, J=
8.2 Hz, 1H, 9-H), 7.99 (s, 1H, 4-H), 8.13 (d, J=8.2 Hz, 1H, 6-H), 10.40
(s, 1H, OH), 11.18 (brs, 1H, NH+), 11.51 ppm (brs, 1H, NH); 13C NMR
(75 MHz, [D6]DMSO): d=23.4 (C-11), 42.8 (NMe2), 45.9 (C-1), 52.1 (C-
2), 55.3 (C-2’’), 55.6 (OCH3), 61.5 (C-10), 64.6 (C-1’’), 94.7 (C-7’), 100.4
(C-4), 105.9 (C-3’), 106.6 (C-4’), 115.6 (C-5a), 120.1 (C-3a’), 122.1 (C-9b),
122.7, 122.8 (C-7, C-9), 123.1 (C-6), 126.9 (C-8), 129.4, 129.8 (C-2’, C-9a),
132.3 (C-7a’), 142.3 (C-3a), 143.4 (C-5’), 149.3 (C-6’), 153.8 (C-5),
159.7 ppm (C=O); IR (KBr): n˜ =3385, 1612, 1587, 1516, 1471, 1415, 1313,
1201, 1153 cmꢀ1; UV (MeOH): lmax (lg e)=206.0 (4.653), 245.5 (4.321),
349.5 nm (4.492); MS (ESI): m/z (%): 508.2 (100) [M +ꢀCl]; HRMS
(ESI): m/z: calcd for C28H31ClN3O4: 508.2003; found: 508.1998 [M +].
(+)-{(1S,10R)-1-(10-Chloroethyl)-5-hydroxy-3-[(5-(1-methylpiperidin-4-
yl-methoxy)-indol-2-yl)-carbonyl]-1,2-dihydro-3H-benz[e]indole hydro-
chloride} [(+)-(1S,10R)-14e]: According to GP 3, benzyl ether (+)-13e
(90 mg, 148 mmol) was stirred in 4m HCl/EtOAc. After that, a suspension
of the residue was treated with Pd/C (10%, 32 mg) and a 25% (w/w)
aqueous solution of NH4HCO2 (0.32 mL), and the resulting mixture was
stirred for 75 min at 408C. Purification of the crude product by column
chromatography on silica gel (CH2Cl2/MeOH 5:1, 0.1% conc. HCl) pro-
vided seco-drug hydrochloride (+)-14e (67 mg, 121 mmol, 82%) as a
yellow solid. Rf =0.33 (CH2Cl2/MeOH 5:1, 1% conc. HCl); [a]D20
=
+44.2 (c=0.33, MeOH); 1H NMR (300 MHz, [D6]DMSO): d=1.60 (d,
J=6.5 Hz, 3H, 11-H3), 1.64–1.82 (m, 2H, 3’’’-Hax, 5’’’-Hax), 1.87–2.09 (m,
3H, 3’’’-Heq, 4’’’-H, 5’’’-Heq), 2.67 (s, 3H, NCH3), 2.85–3.04 (m, 2H, 2’’’-
Hax, 6’’’-Hax), 3.26–3.45 (m, 2H, 2’’’-Heq, 6’’’-Heq), 3.85 (m, 2H, 1’’-H2),
4.14 (m, 1H, 1-H), 4.47–4.79 (m, 3H, 2-H2, 10-H), 6.91 (m, 1H, 6’-H),
7.11, 7.16 (2”brs, 2H, 3’-H, 4’-H), 7.28–7.44 (m, 2H, 7-H, 7’-H), 7.48 (m,
1H, 8-H), 7.86 (d, J=8.3 Hz, 1H, 9-H), 7.96 (brs, 1H, 4-H), 8.12 (d, J=
8.3 Hz, 1H, 6-H), 10.43 (s, 1H, OH), 10.97 (brs, 1H, NH+), 11.59 ppm (s,
1H, NH); 13C NMR (75 MHz, [D6]DMSO): d=23.4 (C-11), 25.8 (C-3’’’,
C-5’’’), 32.8 (C-4’’’), 42.5 (NCH3), 45.8 (C-1), 52.1 (C-2), 52.8 (C-2’’’, C-
6’’’), 61.5 (C-10), 71.7 (C-1’’), 100.4 (C-4), 103.6, 105.2 (C-3’, C-4’), 113.1
(C-7’), 115.6, 115.8 (C-6’, C-5a), 122.2, 122.8, 122.9, 123.1 (C-6, C-7, C-9,
C-9b), 126.9 (C-8), 127.5 (C-3a’), 129.8, 131.1, 131.7 (C-2’, C-7a’, C-9a),
142.1 (C-3a), 152.9 (C-5’), 153.9 (C-5), 159.8 ppm (C=O); IR (KBr): n˜ =
3405, 2672, 1625, 1587, 1517, 1469, 1411, 1280 cmꢀ1; UV (MeOH): lmax (lg
e)=202.0 (4.676), 248.0 (4.356), 303.0 (4.450), 339.5 nm (4.362); MS
(ESI): m/z (%): 518.0 (100) [M +ꢀCl]; HRMS (ESI): m/z: calcd for
C30H33ClN3O3: 518.2210; found: 518.2205 [M +ꢀCl].
(+)-{(1S,10R)-1-(10-Chloroethyl)-3-[(5-(2-N,N-dimethylaminoacetylami-
no)-indol-2-yl)-carbonyl]-5-hydroxy-1,2-dihydro-3H-benz[e]indole hydro-
chloride} [(+)-(1S,10R)-14c]: According to GP 3, benzyl ether (+)-13c
(80 mg, 138 mmol) was stirred in 4m HCl/EtOAc. After that, a suspension
of the residue was treated with Pd/C (10%, 30 mg) and a 25% (w/w)
aqueous solution of NH4HCO2 (0.30 mL), and the resulting mixture was
stirred for 40 min at 408C. Purification of the crude product by column
chromatography on silica gel (MeOH, 0.1% conc. HCl) provided a solid
which was then dissolved in MeOH, 0.1% conc. HCl. Unsoluble silica
gel was removed by filtration and the filtrate was concentrated in vacuo
to give seco-drug hydrochloride (+)-14c (78 mg, 116 mmol, 84%) as a
green solid. Rf =0.62 (MeOH, 0.1% conc. HCl); [a]2D0 = +68.3 (c=0.3 in
MeOH); 1H NMR (300 MHz, [D6]DMSO): d=1.63 (d, J=6.3 Hz, 3H,
11-H3), 2.90 (s, 6H, NMe2), 4.11–4–25 (m, 3H, 1-H, 1’’-H2), 4.53–4.64 (m,
1H, 2-Ha), 4.65–4.81 (m, 2H, 2-Hb, 10-H), 7.21–7.55 (m, 5H, 3’-H, 6’-H,
7-H, 7’-H, 8-H), 7.88 (d, J=8.3 Hz, 1H, 9-H), 7.99 (brs, 1H, 4-H), 8.07–
8.19 (m, 2H, 4’-H, 6-H), 10.30 (brs, 1H, OH), 10.43, 11.03, 11.73 ppm
(3”s, 3H, 2”NH, NH+); 13C NMR (75 MHz, [D6]DMSO): d=23.3 (C-
11), 43.1 (NMe2), 45.8 (C-1), 52.1 (C-2), 57.9 (C-1’’), 61.5 (C-10), 100.3
(C-4), 105.6 (C-3’), 112.1, 112.3 (C-4’, C-7’), 115.9 (C-5a), 118.0 (C-6’),
122.2, 122.9 (2 signals), 123.1 (C-6, C-7, C-9, C-9b), 126.9, 127.0 (C-3a’,
C-8), 129.7, 130.8, 131.4, 133.3 (C-2’, C-5’, C-7a’, C-9a), 142.1 (C-3a),
153.8 (C-5), 159.7 (C=O), 162.4 ppm (C=O); IR (KBr): n˜ =3206, 1682,
Cell culture: Human bronchial carcinoma cells of line A549 (ATCC CCL
185) were kindly provided by the Institut für Zellbiologie, Universität
Essen (Germany), and were maintained as exponentially growing cul-
tures at 378C and 7.5% CO2 in air in Dulbeccoꢁs modified Eagleꢁs
medium (DMEM) (Biochrom, Berlin, Germany) supplemented with
10% fetal calf serum (heat-inactivated for 30 min at 568C, GibcoBRL,
Karlsruhe, Germany), 44 mm NaHCO3 (Biochrom, Berlin, Germany) and
4 mm l-glutamine (GibcoBRL, Karlsruhe, Germany).
In vitro cytotoxicity assays: Adherent cells of line A549 were sown in
triplicate in six multiwell plates at concentrations of 102, 103, 104 and 105
cells per cavity. Culture medium was sucked off after 24 h and cells were
washed in the incubation medium Ultraculture (UC, serum-free special
medium, purchased from BioWhittaker Europe, Verviers, Belgium). In-
cubation with compounds (+)-12a–e and (+)-14a–e was then performed
in Ultraculture medium at various concentrations for 24 h. All substances
were used as freshly prepared solutions in DMSO (Merck, Darmstadt,
Germany) diluted with incubation medium to a final concentration of
DMSO of 1% in the wells. After 24 h of exposure the test substance was
1589, 1518, 1473, 1412, 1252 cmꢀ1
; UV (MeOH): lmax (lg e)=207.5
(4.484), 257.0 (4.499), 303.5 (4.409), 337.5 nm (4.328); MS (ESI): m/z
(%): 981.0 (11) [2M ++H], 491.1 (100) [M +ꢀCl]; HRMS (ESI): m/z:
calcd for C27H28ClN4O3: 491.1850; found 491.1844 [M +].
(+)-{(1S,10R)-1-(10-Chloroethyl)-5-hydroxy-3-[(5-(2-morpholin-4-yl-
ethoxy)-indol-2-yl)-carbonyl]-1,2-dihydro-3H-benz[e]indole
hydrochlo-
ride} [(+)-(1S,10R)-14d]: According to GP 3, benzyl ether (+)-13d
(80 mg, 131 mmol) was stirred in 4m HCl/EtOAc. After that, a suspension
of the residue was treated with Pd/C (10%, 28 mg) and a 25% (w/w)
Chem. Eur. J. 2007, 13, 4396 –4409
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L. F. Tietze et al.
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Acknowledgement
This research was supported by the Deutsche Forschungsgemeinschaft
(Sonderforschungsbereich 416) and the Fonds der Chemischen Industrie.
F.M. thanks the Studienstiftung des deutschen Volkes (German National
Academic Foundation) and B.K. the Deutsche Telekom Stiftung for a
Ph.D. scholarship.
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Chem. Eur. J. 2007, 13, 4396 –4409

Analogues of the Antibiotic CC-1065 and Duocarmycins
FULL PAPER
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Received: January 23, 2007
Published online: April 23, 2007
Chem. Eur. J. 2007, 13, 4396 –4409
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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