Targeting mitochondria: Esters of rhodamine B with triterpenoids are mitocanic triggers of apoptosis

Article abstract of DOI:10.1016/j.ejmech.2018.04.031

Triterpenoic acids, ursolic acid (1), oleanolic acid (2), glycyrrhetinic acid (3) and betulinic acid (4) were converted into their corresponding methyl 5–8 and benzyl esters 9–12 or benzyl amides 21–24. These derivatives served as starting materials for the synthesis of pink colored rhodamine B derivatives 25–36 which were screened for cytotoxicity in colorimetric SRB assays. All of the compounds were cytotoxic for a variety of human tumor cell lines. The activity of the benzyl ester derivatives 29–32 was lower than the cytotoxicity of the methyl esters 25–28. The benzyl amides 33–36 were the most cytotoxic compounds of this series. The most potential compound was a glycyrrhetinic acid rhodamine B benzyl amide 35. This compound showed activity against the different cancer cell lines in a two-digit to low three-digit nano-molar range. Staining experiments combined with fluorescence microscopy showed that this compound triggered apoptosis in A2780 ovarian carcinoma cells and acted as a mitocan.

Full text of DOI:10.1016/j.ejmech.2018.04.031

Accepted Manuscript
Targeting mitochondria: Esters of rhodamine B with triterpenoids are mitocanic
triggers of apoptosis
Ratna Kancana Wolfram, Lucie Heller, René Csuk
PII:
S0223-5234(18)30365-9
10.1016/j.ejmech.2018.04.031
EJMECH 10380
DOI:
Reference:
To appear in: European Journal of Medicinal Chemistry
Received Date: 6 December 2017
Revised Date: 10 April 2018
Accepted Date: 15 April 2018
Please cite this article as: R.K. Wolfram, L. Heller, René. Csuk, Targeting mitochondria: Esters of
rhodamine B with triterpenoids are mitocanic triggers of apoptosis, European Journal of Medicinal
Chemistry (2018), doi: 10.1016/j.ejmech.2018.04.031.
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ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
Targeting mitochondria: esters of rhodamine B with triterpenoids are mitocanic triggers
of apoptosis
Ratna Kancana Wolfram, Lucie Heller, René Csuk*
Martin-Luther-Universität Halle-Wittenberg, Bereich Organische Chemie, Kurt-Mothes-Str.
2, D-06120 Halle (Saale), Germany.
Abstract
Triterpenoic acids, ursolic acid (1), oleanolic acid (2), glycyrrhetinic acid (3) and betulinic
acid (4) were converted into their corresponding methyl 5-8 and benzyl esters 9-12 or benzyl
amides 21-24. These derivatives served as starting materials for the synthesis of pink colored
rhodamine B derivatives 25-36 which were screened for cytotoxicity in colorimetric SRB
assays. All of the compounds were cytotoxic for a variety of human tumor cell lines. The
activity of the benzyl ester derivatives 29-32 was lower than the cytotoxicity of the methyl
esters 25-28. The benzyl amides 33-36 were the most cytotoxic compounds of this series. The
most potential compound was a glycyrrhetinic acid rhodamine B benzyl amide 35. This
compound showed activity against the different cancer cell lines in a two-digit to low three-
digit nano-molar range. Staining experiments combined with fluorescence microscopy
showed that this compound triggered apoptosis in A2780 ovarian carcinoma cells and acted as
a mitocan.
1.
Introduction
Mitochondria, cytoplasmatic organelles, are important and critical for normal cell
functions. They are, however, not only the power-plants of the cell but they also take part in
the regulation of cell signaling and of cell death, and they are regulators of tumorigenesis.
Thus, a next generation of cytotoxic agents for treating cancer is likely to be developed from
compounds targeting mitochondria.[1-3] Compounds like these are also known [3] as
mitocans, and they might prove as efficient cytotoxic agents that can developed into selective
cytotoxic drugs targeting cancer, inasmuch as previous studies showed an increased
mitochondrial membrane potential for malignant cells.[4] Mitocans derived from lipophilic
cations act on the inner mitochondrial membrane.[5] Recently, our group reported an
increased cytotoxic activity for triterpenoid piperazine-spacered rhodamine B derivatives. In
colorimetric sulforhodamine B assays (SRB) EC50 values in nano-molar concentrations were
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observed for these compounds while parent rhodamine B and the unsubstituted triterpenoic
acids were not cytotoxic at all (EC50 > 30 µM).[6] Rhodamine B derivatives are widely used
as fluorescent probes [7-13], e.g. in biological assays, while substituted rhodamine B
triterpenoid derivatives [originating, for example, from ursolic acid (1), oleanolic acid (2),
glycyrrhetinic acid (3) and betulinic acid (4) (Fig. 1)] were merely investigated so far [6].
In previous works the significant role of the presence of the carboxyl group in
triterpenes and of the substituent at C-3 for obtaining compounds of high cytotoxic potency
and good tumor cell/nonmalignant cell selectivity has been shown [14].
Fig. 1. Structure of important pentacyclic triterpenoic acids: ursolic acid (1), oleanolic acid
(2), glycyrrhetinic acid (3) and betulinic acid (4).
Therefore, we decided to synthesize some pentacyclic triterpenoic acid derivatives
coupled at C-3 position directly with rhodamine B. The antitumor activities of these
compounds were screened using SRB assays employing different human cancer cell lines.
Their ability to accumulate in the mitochondria and to trigger apoptosis was investigated in
more detail.
2.
Results and discussion
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2.1. Chemistry
The starting materials 1-4 were purchased from different suppliers. The synthesis of
the methyl and benzyl ester as well as of the N-benzyl amides are presented in Scheme 1.
Triterpenoic acids (TP, 1-4) were treated with MeI or BnBr in the presence of K2CO3 in DMF
at ambient temperature to afford the corresponding methyl or benzyl ester derivatives (5-8, 9-
12) in 70-90% or 55-62% yields, respectively.
Scheme 1. Synthesis of triterpenoic acids derivatives 5-24: a) MeI, K2CO3, DMF, rt, 24 h, 70-
90%; b) BnBr, K2CO3, DMF, rt, 24 h, 55-62%; c) Ac2O, reflux, 2 h, 70-90%; d) 1. (COCl)2,
DCM, rt, 3 h 2. BnNH2, TEA, DMAP, DCM, rt, 24 h, 65-95%; e) KOH, MeOH, rt, 3 d, 76-
94%.
To obtain N-benzyl amide derivatives, HO-C-3 of the triterpenoic acids 1-4 had to be
protected by acetylation. Activation of the acetates 13-16 at C-28 or C-30 carboxyl group
with oxalyl chloride followed by reaction with benzyl amine gave compounds 17-20 in 65-
95% yields. Afterwards deacetylation of 17-20 with KOH in methanol at ambient temperature
furnished the deprotected triterpenoic acid N-benzyl amide derivatives 21-24 in 76-94%
yields.
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Scheme 2. Esterification of rhodamine B with triterpenoic acid derivatives at C-3 positions.
Scheme 2 shows the coupling of triterpenoic acids derivatives and rhodamine B.
Firstly, rhodamine B was activated [15] with oxalyl chloride followed by reactions with the
corresponding methyl esters 5-8, benzyl esters 9-12 or benzyl amides 21-24. The desired
rhodamine B triterpenoic acid methyl esters 25-28, benzyl esters 29-32, amides 33-36 were
obtained in good to moderate yields; the lower yields of product are due to loss during
chromatographic purification.
2.2. Biology
The cytotoxicity of the rhodamine B derivatives 25-36, parent triterpenoic acids 1-4
and rhodamine B (Rh) were evaluated in SRB-assays, the results of which are summarized in
Table 1.
In general, the screening results showed for all of the tested compounds potent
cytotoxic activity with EC50 values ranging from 0.02 ± 0.001 to 15.79 ± 1.15 µM.
Furthermore, the screening results revealed that the activity for benzyl esters 29-32 was lower
than the cytotoxicity of the methyl esters 25-28; benzyl amides 33-36 were the most cytotoxic
derivatives. Thus, the presence of a benzyl ester as protecting group (as in 29-32) seems to be
disadvantageous for obtaining compounds of high cytotoxicity while for benzyl amides 33-36
the opposite is true. With respect to the backbone of the triterpenoic acids, the data showed an
extra ordinarily higher potency for the glycyrrhetinic acid rhodamine B derivatives 27, 31 and
35. This finding was somewhat surprising since the cytotoxicity of parent glycyrrhetinic acid
3 is lower than the cytotoxicity of the other parent triterpenoic acids of this study.
Consequently, the most potential compound found during the investigation was the
glycyrrhetinic acid rhodamine B benzyl amide derivative 35 which shows activity against the
different cancer cell lines in a two-digit to low three-digit nano-molar range.
Compound 35 was investigated in cell imaging experiments to elucidate its mechanism of
action. Fluorescence microscopic studies with fluorescent dyes rhodamine 123 and Hoechst
33342 revealed compound 35 is not accumulated in the nucleus, but in the mitochondria of
ovarian carcinoma cells A2780 as indicated by double staining experiments with rhodamine
123. These double stained cells showed overlapping patterns of green and red fluorescence
(Fig. 2B). Furthermore, these cells showed after treatment with 35 and Hoechst 33342
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crescent-shaped nuclei - a characteristic hallmark of apoptosis (Fig. 2D). In addition, incipient
membrane blebbing was detected. Thus, compound 35 is cytotoxic by triggering of apoptosis,
and it acts as a mitocan. At this point no statement can be made if and to which extent the
number of mitochondria and/or their generation is influenced, too.
Table 1. Cytotoxicity of selected compounds (EC50 values in µM from SRB assays after 96 h
of treatment, the values are averaged from three independent experiments performed each in
triplicate, confidence interval CI = 95%, cut-off the assay 30 µM, n.m. not measured). Human
cancer cell lines: FADU (squamous carcinoma), A2780 (ovarian carcinoma), HT29
(colorectal adenocarcinoma), MCF7 (breast adenocarcinoma), SW1736 (thyroidea
carcinoma), NIH 3T3 (non-malignant mouse fibroblasts). Data for 1-4 are taken from
literature [references: 6, 16, 17].
Compound
FADU
A2780
HT29
MCF7
NiH3T3
SW1736
n. m.
11.7±0.6
10.6±0.7
12.7±0.1
>60
18.7±1.6
n. m.
n. m.
1
n. m.
14.0±2.3
38.8±3.1
76.4±0.7
2
84.55±4.23
n. m.
74.57±3.73
8.8±0.9
80.09±4.00
14.4±2.3
84.70±4.24
10.2±1.2
1.83±0.11
2.31±0.13
0.18±0.01
0.81±0.12
13.75±1.47
9.40±0.27
1.47±0.13
5.05±0.25
0.30±0.01
0.36±0.03
0.040±0.002
0.47±0.04
18.52±0.93
16.1±1.4
76.93±3.85
n. m.
3
4
1.96±0.16
1.99±0.17
0.19±0.04
1.29±0.26
15.79±1.15
9.12±0.24
1.54±0.28
7.59±0.46
0.44±0.04
0.50±0.04
0.06±0.01
0.54±0.06
1.75±0.01
1.14±0.18
0.08±0.01
0.42±0.04
10.1±0.95
3.35±0.15
0.90±0.03
3.36±0.13
0.34±0.02
0.32±0.02
0.020±0.001
0.31±0.01
1.85±0.08
2.75±0.38
0.15±0.02
0.61±0.12
11.41±1.79
8.90±0.31
1.42±0.13
5.33±0.35
0.45±0.04
0.46±0.16
0.06±0.01
0.53±0.05
1.84±0.08
2.63±0.20
0.20±0.02
1.77±0.10
15.42±1.60
11.25±1.37
1.28±0.12
8.04±0.28
0.37±0.07
0.40±0.03
0.08±0.01
0.54±0.06
1.72±0.12
1.76±0.11
0.15±0.01
0.74±0.09
12.66±1.14
9.05±0.53
1.13±0.12
6.43±0.72
0.24±0.02
0.27±0.03
0.04±0.01
0.45±0.02
25
26
27
28
29
30
31
32
33
34
35
36
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Fig. 2. Fluorescence microscopic investigation of compound 35 (200 nM) after 24 h
incubation of A2780 ovarian carcinoma cells. (A) compound 35, (B) overlay of A and C, (C)
Rhodamine 123, (D) Hoechst 33342, (E) overlay of A, C and D, (F) bright field; scale bar =
10 µm.
3.
Conclusion
Triterpenoic acids, 1-4 were converted into their corresponding methyl 5-8 and benzyl esters
9-12 or benzyl amides 21-24. These derivatives were transformed into pink colored
rhodamine B derivatives 25-36. Screening of these compounds for cytotoxicity in colorimetric
SRB assays was performed, and of the compounds were cytotoxic for a variety of human
tumor cell lines. The activity of the benzyl ester derivatives 29-32 was lower than the
cytotoxicity of the methyl esters 25-28. The benzyl amides 33-36 were the most cytotoxic
compounds of this series. Thus, the most potential compound was a glycyrrhetinic acid
rhodamine B benzyl amide 35. This compound showed activity against the different cancer
cell lines in a two-digit to low three-digit nano-molar range. Staining experiments combined
with fluorescence microscopy showed that this compound triggered apoptosis in A2780
ovarian carcinoma cells and acted as a mitocan.
4.
Experimental part
4.1. General
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Melting points were determined on Leica hot stage microscope and in open capillaries
on Büchi M-565 melting point apparatus and are uncorrected, NMR spectra were recorded on
Varian spectrometers Gemini 2000 or Unity 500 (δ given in ppm, J in Hz), mass spectra were
obtained on a Finnigan MAT LCQ 7000 (electrospray, voltage 4.1 kV, sheath gas nitrogen)
instrument. The optical rotations were measured on a Perkin-Elmer polarimeter at 20 °C.
Merck 5554 pre-coated silica gel 60 F254 plates were used for thin layer chromatography. IR
spectra were recorded on a Perkin-Elmer FT-IR spectrometer Spectrum 1000 and wave
numbers are expressed in cm-1. The absorption spectra were measured on Perkin Elmer
Lambda14 spectrometer. The solvents were dried according to usual procedures. The SRB
assays were performed as previously reported [6, 16, 18, 19]. The purity of the products was
> 97% (HPLC).
4.2. General procedures
4.2.1. General procedure for the synthesis of methyl and benzyl esters (GP1)
To a solution of the triterpenoic acid (10.0 g, 22.0 mmol, 1.0 eq.) in DMF (100 mL) finely
grounded potassium carbonate (3.3 g, 24.0 mmol, 1.1 eq.) was added. After stirring at
ambient temperature for 30 min methyl iodide (3.7 g, 1.6 mL, 26 mmol, 1.2 eq.) or benzyl
bromide (4.1 g, 2.9 mL, 24 mmol, 1.1 eq.) was added, and stirring was continued for 24 h.
The mixture was slowly added to 5% hydrochloric acid (300 mL), and the precipitate was
filtered off and washed with water (2×100 mL). After purification by re-crystallisation from
methanol or by chromatography (silica gel, hexane/ethyl acetate) the esters were obtained as
white solids.
4.2.2. General procedure for acetylation (GP2)
A solution of the triterpenoic acid (10 g, 22 mmol, 1.0 eq.) in acetic anhydride (160 mL) was
stirred at reflux for 2 h. To the hot reaction mixture acetic acid (20 mL) and water (40 mL)
were slowly added. The precipitate was filtered off, washed with water (4×50 mL), cold
EtOH (20 mL) and dried under reduced pressure. The products were obtained as white solids.
4.2.3. General procedure for the synthesis of amides (GP3)
To an ice-cold solution of the triterpenoic acetate (3.0 g, 5.9 mmol, 1.0 eq.) in dry DCM
(50 mL), oxalyl chloride (3.0 g, 2.0 mL, 23.4 mmol, 4.0 eq.) was slowly added, and the
mixture was allowed to warm to ambient temperature; stirring was continued for 3 h. The
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solvent was removed under reduced pressure, the residue dissolved in dry THF (20 mL), and
volatiles were evaporated again. To a solution of the residue in dry DCM (50 mL), benzyl
amine (1.9 g, 1.9 mL, 17.6 mmol, 3.0 eq.), NEt3 (0.6 g, 0.8 mL, 5.8 mmol, 1 eq.) and DMAP
(5 mol-%) were added, and stirring was continued overnight. Evaporation of the solvent under
reduced pressure and purification of the residue by chromatography (silica gel, hexane/ethyl
acetate) afforded the desired amides as white solids.
4.2.4. General procedure for deacetylation (GP4)
To a solution of the acetate (1.7 mmol, 1 eq.) in MeOH (20 mL) KOH (0.6 g, 8.9 mmol, 5 eq.)
was added, and the mixture was stirred at ambient temperature for 3 d. The mixture was
slowly added to hydrochloric acid (1 M, 15 mL). The aqueous phase was extracted with DCM
(4 x15 mL), the combined organic phases were washed with water (20 mL), brine (20 mL)
and dried over MgSO4. Evaporation of the solvent under reduced pressure and purification of
the residue by chromatography (silica gel, hexane/ethyl acetate) afforded the desired products
as white solids.
4.2.5. General procedure for the preparation of the rhodamine B derivatives (GP5)
To an ice-cold solution of rhodamine B (0.56 g, 1.16 mmol, 1 eq.) in dry DCM (10 mL),
oxalyl chloride (0.58 g, 0.4 mL, 4.64 mmol, 4 eq.) was slowly added, and the mixture was
allowed to warm to ambient temperature and stirring was continued for 3 h. The solvent was
removed under reduced pressure, the residue dissolved in dry THF (2×10 mL) and volatiles
were evaporated again. To a solution of the residue (0.676 g, 1.36 mmol, 1.5 eq.) in dry DCM
(15 mL) triterpenoic acid esters or amides (0.89 mmol, 1 eq.), NEt3 (0.13 g, 0.19 mL,
1.34 mmol, 1.5 eq.) and DMAP (5 mol-%) were added, and stirring was continued overnight.
Evaporation of the solvent under reduced pressure and purification of the residue by
chromatography (silica gel, ACN/DCM/H2O 10:1:1) afforded the desired rhodamine B
derivatives as intensive violet solids.
4.3.Syntheses
4.3.1. Methyl 3ß-hydroxy-urs-12-en-28-oate, ursolic acid methyl ester (5)
Following GP1 1 was transformed to 5 in 85% yield; m.p. 170–172 °C, [α]ꢀ = +58.16° (c
0.32, CHCl3), (lit.: m.p. 172–173 °C [20], [α]ꢀ = +68° (c 0.53, CHCl3) [18]).
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4.3.2. Methyl 3ß-hydroxy-olean-12-en-28-oate, oleanolic acid methyl ester (6)
Following GP1 2 was transformed to 6 in 80% yield; m.p. 197–200 °C, [α]ꢀ = +67.9° (c 0.32,
CHCl3), (lit.: m.p. 198–200 °C, [α]ꢀ = +70° (c 0.43, CHCl3)) [17].
4.3.3. Methyl 3ß-hydroxy-11-oxo-20ß-olean-12-en-29-oate, 18ß-glycyrrhetinic acid
methyl ester (7)
Following GP1 3 was transformed to 7 in 92% yield; m.p. 251–255°C, [α]ꢀ = +163.3° (c
0.33, CHCl3), (lit.: m.p. 254–258 °C, [α]ꢀ = +141.2° (c 0.48, CHCl3)) [21].
4.3.4. Methyl 3ß-hydroxy-lup-20(29)-en-28-oate, betulinic acid methyl ester (8)
Following GP1 4 was transformed to 8 in 70% yield; m.p. 226–228 °C, [α]ꢀ = +5.54° (c 0.34,
CHCl3), (lit.: m.p. 222–224 °C, [α]ꢀ = +3.2° (c 0.62, CHCl3)) [19].
4.3.5. Benzyl 3ß-hydroxy-urs-12-en-28-oate, ursolic acid benzyl ester (9)
Following GP1 1 afforded 9 in 62% yield; m.p. 184–189 °C, [ꢁ]ꢂ = +48.42° (c 0.36, CHCl3),
(lit.: m.p. 180–182 °C, [ꢁ]ꢂ = +45.6° (c 0.30, CHCl3)) [16].
4.3.6. Benzyl 3ß-hydroxy-olean-12-en-28-oate, oleanolic acid benzyl ester (10)
Following GP1 2 afforded 10 in 60% yield; m.p. 186–191 °C, [ꢁ]ꢂ = +58.53° (c 0.31,
CHCl3), (lit.: m.p. 185–187 °C, [ꢁ]ꢂ = +58.4° (c 0.45, CHCl3)) [16].
4.3.7. Benzyl 3ß-hydroxy-11-oxo-20ß-olean-12-en-29-oate, 18ß-glycyrrhetinic acid benzyl
ester (11)
Following GP1 3 afforded 12 in 55% yield; m.p. 134–137 °C, [α]ꢀ = +127.31° (c 0.32,
CHCl3), (lit.: m.p. 134–137 °C, [α]ꢀ = +136.4° (c 0.25, CHCl3)) [21].
4.3.8. Benzyl 3ß-hydroxy-lup-20(29)-en-28-oate, betulinic acid benzyl ester (12)
Following GP1 to a solution of 4 (10 g, 22 mmol, 1 eq.) in DMF (150 mL), finely grounded
potassium carbonate (3.1 g, 24 mmol, 1.0 eq.) and benzyl bromide (4.1 g, 2.9 mL, 24 mmol,
1.1 eq.) were added. After work-up as described followed by re-crystallisation from EtOH 12
was obtained as an off-white solid in 57% yield; m.p. 183–185 °C, [α]ꢀ = +12.96° (c 0.36,
CHCl3) (lit.: 202 °C, [α]ꢀ = -2.0 (c 1.0, EtOH) [22]); UV-Vis (MeOH): λmax (log
ε) = 267 nm (3.44); IR (KBr, cm-1): ῦ = 3448br, 2943s, 1694s, 1647m, 1452m, 1375m,
1
1219m, 1164m, 1042m, 960m, 889m, 759m, 699m; H NMR (400 MHz, CDCl3):
δ
= 7.38–
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7.29 (m, 5 H, Ph), 5.15 (d, J = 12.3 Hz, 1 H, CHaPh), 5.09 (d, J = 12.3 Hz, 1 H, CHbPh), 4.72
(mc, 1 H, 29-Ha), 4.59 (mc, 1 H, 29-Hb), 3.17 (dd, J = 11.1, 4.8 Hz, 1 H, 3-H), 3.02 (ddd,
J = 11.0, 11.0, 4.4 Hz, 1 H, 19-H), 2.28 (mc, 1 H, 16-Ha), 2.18 (ddd, J = 12.0, 12.0, 3.4 Hz,
1 H, 13-H), 1.95–1.81 (m, 2 H, 21-Ha, 22-Ha), 1.68 (s, 3 H, 30-H3), 1.71–1.63 (m, 2 H, 1-Ha,
12-Ha), 1.62–1.46 (m, 4 H, 18-H, 6-Ha, 2-H2), 1.45–1.19 (m, 10 H, 22-Hb, 21-Hb, 16-Hb,
15-Ha, 11-H2, 7-H2, 6-Hb, 9-H), 1.13–1.00 (m, 2 H, 15-Hb, 12-Hb), 0.95 (s, 3 H, 27-H3), 0.94
(s, 3 H, 26-H3), 0.90–0.83 (m, 1 H, 1-Hb), 0.80 (s, 3 H, 23-H3), 0.76 (s, 3 H, 25-H3), 0.75 (s,
3 H, 24-H3), 0.66 (mc, 1 H, 5-H) ppm; 13C NMR (100 MHz, CDCl3):
δ = 175.8 (C-28), 150.5
(C-20), 136.5 (Ci-Ph), 128.5, 128.2 (Co-Ph, Cm-Ph), 128.0 (Cp-Ph), 109.5 (C-29), 79.0 (C-3),
65.7 (CH2Ph), 56.5 (C-17), 55.3 (C-5), 50.6 (C-9), 49.5 (C-18), 46.9 (C-19), 42.4 (C-14), 40.7
(C-8), 38.8 (C-4), 38.7 (C-1), 38.2 (C-13), 37.2 (C-10), 36.9 (C-22), 31.3 (C-7), 32.1 (C-16),
30.6 (C-21), 29.6 (C-15), 28.0 (C-23), 27.4 (C-12), 25.5 (C-2), 20.9 (C-11), 19.4 (C-30), 18.3
(C-6), 16.1 (C-24), 15.8 (C-25), 15.3 (C-26), 14.7 (C-27) ppm; MS (ESI, MeOH): m/z (%)
1115.2 (100) [2M+Na]+, 569.3 (30) [M+Na]+, 547.3 (49) [M+H]+, 529.2 (67) [M+H–H2O]+.
4.3.9. 3ß-Acetoxy-urs-12-en-28-oic acid, 3-O-acetyl-ursolic acid (13)
Following GP2 1 afforded 13 in 90% yield; m.p. 280–285 °C, [α]ꢀ = +65.59° (c 0.33,
CHCl3), (lit.: m.p. 285 °C [23], [α]ꢀ = +69° (c 0.19, CHCl3) [16]).
4.3.10. 3ß-Acetoxy-olean-12-en-28-oic acid, 3-O-acetyl-oleanolic acid (14)
Following GP2 2 (10 g, 22 mmol, 1.0 eq.) gave 14 in 73% yield; m.p. 266–269 °C,
[α]ꢀ = +69.4° (c 0.30, CHCl3), (lit.: m.p. 265–268 °C [24], [α]ꢀ = +65° (c 0.33, CHCl3) [16]).
4.3.11. 3ß-Acetoxy-11-oxo-20ß-olean-12-en-29-oic acid, 3-O-acetyl-18ß-glycyrrhetinic acid
(15)
Following GP2 a solution of 3 (10 g, 22 mmol, 1.0 eq.) in acetic anhydride (160 mL) was
stirred under reflux for 2 h. Work-up as described followed by filtration afforded the desired
product 15 in 85% yield as an white solid; m.p. 316–318 °C, [α]ꢀ = +142.44° (c 0.33, CHCl3)
(lit.: m.p. 319–332 °C [25], [α]ꢀ = +150.0° (c 0.04, MeOH) [26] UV-Vis (MeOH): λmax (log
ε) = 263 nm (3.97); IR (KBr, cm-1): ῦ = 3432br, 2956m, 1730s, 1705m, 1646s, 1451m,
1383m, 1276m, 1259m, 1143m, 1090m, 985m; 1H NMR (400 MHz, CDCl3):
δ = 5.71 (s, 1 H,
12-H), 4.52 (dd, J = 11.8, 4.7 Hz, 1 H, 3-H), 2.79 (ddd, J = 13.6, 3.5, 3.5 Hz, 1 H, 1-Ha), 2.37
(s, 1 H, 9-H), 2.19 (dd, J = 13.4, 3.6 Hz, 1 H, 18-H), 2.04 (s, 3 H, CH3CO), 2.07–1.97 (m,
2 H, 16-Ha, 21-Ha), 1.94 (ddd, J = 13.7, 4.1, 2.6 Hz, 1 H, 19-Ha), 1.83 (ddd, J = 13.6, 13.6,
10

ACCEPTED MANUSCRIPT
4.4 Hz, 1 H, 15-Ha), 1.75–1.55 (m, 5 H, 2-H2, 7-Ha, 19-Hb, 6-Ha), 1.49–1.38 (m, 4 H, 6-Hb,
7-Hb, 22-H2), 1.37 (s, 3 H, 27-H3), 1.36–1.30 (m, 1 H, 21-Hb), 1.22 (s, 3 H, 29-H3), 1.19 (mc,
1 H, 15-Hb), 1.16 (s, 3 H, 24-H3), 1.13 (s, 3 H, 26-H3), 1.09–0.99 (m, 2 H, 1-Hb, 16-Hb), 0.87
13
(s, 6 H, 25-H3, 23-H3), 0.83 (s, 3 H, 28-H3), 0.80 (dd, J = 11.8, 1.6 Hz, 1 H, 5-H) ppm; C
NMR (100 MHz, CDCl3):
δ = 200.3 (C-11), 181.7 (C-30), 171.0 (CH3CO), 169.4 (C-13),
128.4 (C-12), 80.6 (C-3), 61.7 (C-9), 55.0 (C-5), 48.2 (C-18), 45.5 (C-8), 43.8 (C-20), 43.2
(C-14), 40.8 (C-19), 38.7 (C-1), 38.0 (C-4), 37.7 (C-22), 36.9 (C-10), 32.7 (C-7), 31.9 (C-17),
30.9 (C-21), 28.5 (C-28), 28.4 (C-29), 28.0 (C-23), 26.5 (C-15), 26.4 (C-16), 23.6 (C-2), 23.3
(C-27), 21.3 (CH3CO), 18.7 (C-26), 17.4 (C-6), 16.7 (C-25), 16.4 (C-24) ppm; MS (ESI,
MeOH): m/z (%) 1045.5 (14) [2M-2H+Na]-, 1023.3 (100) [2M-H]-, 557.9 (6) [M+HCO2]-,
511.4 (56) [M-H]-.
4.3.12. 3ß-Acetoxy-lup-20(29)-en-28-oic acid; 3-O-acetyl-betulinic acid (16)
Following GP2 4 afforded 16 in 70% yield; m.p. 282–285 °C, [ꢁ]ꢂ = +20.98° (c 0.33,
CHCl3), (lit.: m.p. 287–289 °C [27], [ꢁ]ꢂ = +20.5° (c 0.58, CHCl3) [19]).
4.3.13. N-Benzyl 3ß-Acetoxy-urs-12-en-28-amide (17)
Following GP3 1 afforded 17 in 95% yield; m.p. 145 °C, [α]ꢀ = +17.89° (c 0.31, CHCl3),
(lit.: m.p. 197–198 °C [28], [α]ꢀ = +18.6° (c 0.33, CHCl3) [16]).
4.3.14. N-Benzyl 3ß-acetoxy-olean-12-en-28-amide (18)
Following GP3 2 afforded 18 in 95% yield; m.p. 247–249 °C, [α]ꢀ = +30.66° (c 0.35,
CHCl3), (lit.: m.p. 254–259 °C, [α]ꢀ = +29° (c 0.56, CHCl3)) [16].
4.3.15. N-Benzyl 3ß-acetoxy-11-oxo-20ß-olean-12-en-29-amide (19)
Following GP3 3 afforded 19 in 65% yield; m.p. 180–183 °C, [α]ꢀ = +125.22° (c 0.34,
CHCl3).
4.3.16. 3-O-Acetyl-betulinic benzyl amide / N-Benzyl 3ß-acetoxy-lup-20(29)-en-28-amide (20)
Following GP3 4 afforded 20 in 80% yield; m.p. 138–140 °C, [α]ꢀ = +22.19° (c 0.36,
CHCl3), (lit.: m.p. 124–127 °C, [α]ꢀ = +23° (c 0.35, CHCl3)) [19].
4.3.17. N-Benzyl-ursolic amide / N-Benzyl-3ß-hydroxy-urs-12-en-28-amide (21)
11

ACCEPTED MANUSCRIPT
Following GP4 17 afforded 21 in 79% yield; m.p. 273–275 °C, [α]ꢀ = +32.33° (c 0.34,
CHCl3), (lit.: m.p. 272–275 °C, [α]ꢀ = +41.9° (c 0.39, CHCl3)) [16].
4.3.18. N-Benzyl -oleanolic amide / N-Benzyl-3ß-hydroxy-olean-12-en-28-amide (22)
Following GP4 18 afforded 22 in 80% yield; m.p. 249–251 °C, [α]ꢀ = +30.42° (c 0.33,
CHCl3), (Lit.: m.p. 247–249 °C, [α]ꢀ = +30.4° (c 0.56, CHCl3) [16].
4.3.19. N-Benzyl-3ß-hydroxy-11-oxo-20ß-olean-12-en-29-amide (23)
Following GP4 to a solution of 19 (0.5 g, 0.8 mmol, 1 eq.) in MeOH (15 mL) KOH (0.4 g,
3.3 mmol, 4 eq.) was added. Work-up as described and purification by chromatography (silica
gel, hexane/ethyl acetate 7:3) afforded 23 in 94% yield as a white solid; m.p. 227–229 °C,
[α]ꢀ = +12.76° (c 0.30, CHCl3) (lit.: m.p. 233–235°C) [29]; UV-Vis (MeOH): λmax (log
ε) = 250 nm (4.26); IR (KBr, cm-1): ῦ = 3442br, 2950m, 2867m, 1648s, 1528m, 1454m,
1
1387m, 1258m, 1206m, 1047m, 730m; H NMR (500 MHz, CDCl3):
δ = 7.36–7.25 (m, 5 H,
Ph,), 5.94 (t, J = 5.6 Hz, 1 H, NH), 5.55 (s, 1 H, 12-H), 4.49 (dd, J = 14.6, 5.7 Hz, 1 H,
CHaPh), 4.43 (dd, J = 14.6, 5.6 Hz, 1 H, CHbPh), 3.20 (dd, J = 10.7, 4.9 Hz, 1 H, 3-H), 2.76
(ddd, J = 13.5, 3.5, 3.5 Hz, 1 H, 1-Ha), 2.30 (s, 1 H, 9-H), 2.15 (dd, J = 12.9, 4.7 Hz, 1 H,
18-H), 2.04 (ddd, J = 13.6, 13.6, 4.4 Hz, 1 H, 16-Ha), 1.95 (mc, 1 H, 21-Ha), 1.83 (ddd,
J = 13.8, 13.8, 4.6 Hz, 1 H, 15-Ha), 1.80–1.56 (m, 6 H, 19-H2, 2-H2, 7-Ha, 6-Ha), 1.48–1.33
(m, 5 H, 6-Hb, 22-H2, 7-Hb, 21-Hb), 1.35 (s, 3 H, 27-H3), 1.18 (ddd, J = 13.9, 4.3, 2.2 Hz, 1 H,
15-Hb), 1.15 (s, 3 H, 29-H3), 1.12 (s, 3 H, 25-H3), 1.11 (s, 3 H, 26-H3), 1.02 (mc, 1 H, 16-Hb),
0.99 (s, 3 H, 23-H3), 0.94 (ddd, J = 13.3, 13.3, 4.3 Hz, 1 H, 1-Hb), 0.80 (s, 3 H, 24-H3), 0.79
(s, 3 H, 28-H3), 0.68 (dd, J = 11.6, 1.4 Hz, 1 H, 5-H) ppm; 13C NMR (125 MHz, CDCl3):
δ
= 200.0 (C-11), 175.5 (C-30), 169.0 (C-13), 138.6 (Ci-Ph), 128.7 (Cm-Ph), 128.4 (C-12),
127.7 (Co-Ph), 127.5 (Cp-Ph), 78.7 (C-3), 61.8 (C-9), 55.0 (C-5), 48.1 (C-18), 45.3 (C-8), 43.6
(CH2Ph), 43.5 (C-20), 43.2 (C-14), 41.8 (C-19), 39.2 (C-4), 39.1 (C-1), 37.4 (C-22), 37.1
(C-10), 32.8 (C-7), 31.9 (C-17), 31.5 (C-21), 29.5 (C-29), 28.4 (C-28), 28.1 (C-23), 27.3
(C-2), 26.5 (C-15), 26.4 (C-16), 23.3 (C-27), 18.7 (C-26), 17.5 (C-6), 16.3 (C-26), 15.6
(C-24) ppm; MS (ESI, MeOH): m/z (%) 1141.5 (97) [2M+Na]+, 1119.4 (100) [2M+H]+, 582.5
(10) [M+Na]+, 560.4 (92) [M+H]+.
4.3.20. N-Benzyl-3ß-hydroxy-lup-20(29)-en-28-amide (24)
Following GP4 20 afforded 24 in 76% yield; m.p. 250–254 °C, [α]ꢀ = +17.17° (c 0.32,
CHCl3), (lit.: m.p. 246–248 °C, [α]ꢀ = +14.3° (c 0.31, CHCl3)). [19]
12

ACCEPTED MANUSCRIPT
4.3.21. 9-(2-(28-Methoxy-28-oxo-urs-12-en-3ß-oxycarbonyl)phenyl)-3,6-bis(diethylamino)-
xanthylium chloride (25):
Following GP5 to a solution of rhodamine B (0.66 g, 1.39 mmol, 1 eq.) in dry DCM (10 mL),
oxalyl chloride (0.70 g, 0.48 mL, 5.55 mmol, 4 eq.) was added. After work-up as described, to
a solution of the residue in dry DCM (15 mL), 5 (0.55 g, 1.16 mmol, 1 eq.), NEt3 (0.18 g,
0.24 mL, 1.75 mmol, 1.5 eq.) and DMAP (5 mol-%) were added. Work-up as described and
purification by chromatography afforded 25 in 39% yield; m.p. 235–242 °C; UV-Vis
(MeOH): λmax (log ε) = 473 nm (4.87); IR (KBr, cm-1): ῦ = 3442br, 2926m, 1718m, 1648m,
1
1590s, 1467m, 1413m, 1338m, 1274m, 1181m; Rf 0.46 (ACN/DCM/H2O 10:1:1); H NMR
(500 MHz, CDCl3):
δ = 8.23 (dd, J = 7.9, 1.0 Hz, 1 H, 3″-H), 7.79 (dt, J = 7.5, 1.0 Hz, 1 H,
5″-H), 7.73 (dt, J = 7.6, 1.0 Hz, 1 H, 4″-H), 7.32 (dd, J = 7.4, 1.0 Hz, 1 H, 6″-H), 7.15, 7.06
(2 x d, J = 9.5 Hz, 2 H, 1′-H, 8′-H), 6.91, 6.84 (2 x dd, J = 9.5, 2.2 Hz, 2 H, 2′-H, 7′-H), 6.82
(d, J = 2.2 Hz, 2 H, 4′-H, 5′-H), 5.18 (t, J = 3.5 Hz, 1 H, 12-H), 4.44 (dd, J = 10.4, 5.8 Hz,
1 H, 3-H), 3.65 (q, J = 7.0 Hz, 4 H, N(CH2CH3)2), 3.63 (q, J = 7.0 Hz, 4 H, N′(CH2CH3)2),
3.57 (s, 3 H, OMe), 2.19 (d, J = 11.3 Hz, 1 H, 18-H), 1.95 (ddd, J = 13.3, 13.3, 4.2 Hz, 1 H,
16-Ha), 1.85–1.60 (m, 5 H, 11-H2, 15-Ha, 16-Hb, 22-Ha), 1.58 (ddd, J = 13.5, 13.5, 3.9 Hz,
1 H, 22-Hb), 1.53–1.41 (m, 2 H, 21-Ha, 1-Ha), 1.41–1.19 (m, 9 H, 6-H2, 2-H2, 7-H2, 21-Hb,
9-H, 19-H), 1.32 (t, J = 7.0 Hz, 6 H, N(CH2CH3)2), 1.31 (t, J = 7.0 Hz, 6 H, N′(CH2CH3)2),
1.05–0.94 (m, 2 H, 15-Hb, 20-H), 0.98 (s, 3 H, 27-H3), 0.93–0.84 (m, 1 H, 1-Hb), 0.90 (d,
J = 5.9 Hz, 3 H, 30-H3), 0.83 (s, 3 H, 25-H3), 0.81 (d, J = 6.4 Hz, 3 H, 29-H3), 0.72–0.62 (m,
1 H, 5-H), 0.69 (s, 6 H, 23-H3, 24-H3), 0.59 (s, 3 H, 26-H3) ppm; 13C NMR (125 MHz,
CDCl3):
δ = 178.0 (C-28), 165.2 (CO-Rhd), 158.8 (C-9′), 158.0, 157.7 (C-4a′, C-10a′), 155.6,
155.4 (C-3′, C-6′), 138.2 (C-13), 132.9 (C-1″), 132.7 (C-5″), 131.5, 131.2 (C-1′, C-8′), 131.1
(C-2″), 131.0 (C-3″), 130.4 (C-4″), 130.3 (C-6″), 125.2 (C-12), 114.3, 114.1 (C-2′, C-7′),
113.6 (C-8a′, C-9a′), 96.4 (C-4′, C-5′), 82.8 (C-3), 55.2 (C-5), 52.8 (C-18), 51.4 (OMe), 48.0
(C-17), 47.4 (C-9), 46.3, 46.2 (N(CH2CH3)2, N′(CH2CH3)2), 41.9 (C-14), 39.4 (C-8), 39.0
(C-19), 38.8 (C-20), 38.2 (C-1), 37.7 (C-4), 36.7 (C-10), 36.6 (C-22), 32.7 (C-7), 30.6 (C-21),
28.0 (C-23), 27.9 (C-15), 24.1 (C-16), 23.5 (C-27), 23.2 (C-11), 23.0 (C-2), 21.1 (C-30), 18.1
(C-6), 17.0 (C-29), 16.8 (C-26), 16.5 (C-24), 15.4 (C-25), 12.6 (N(CH2CH3)2, N′(CH2CH3)2)
ppm; MS (ESI, MeOH): m/z (%) 896 (100) [M-Cl]+; C59H79ClN2O5 (931.72).
4.3.22. 9-(2-(28-Methoxy-28-oxo-olean-12-en-3ß-oxycarbonyl)phenyl)-3,6-bis(diethylamino)-
xanthylium chloride (26)
13

ACCEPTED MANUSCRIPT
Following GP5 to a solution of rhodamine B (0.56 g, 1.17 mmol, 1 eq.) in dry DCM (15 mL),
oxalyl chloride (0.59 g, 0.40 mL, 4.70 mmol, 4 eq.) was added. After work-up as described, to
a solution of the residue in dry DCM (15 mL), 6 (0.45 g, 0.93 mmol, 1 eq.), NEt3 (0.14 g,
0.20 mL, 1.40 mmol, 1.5 eq.) and DMAP (5 mol-%) were added. Work-up as described and
purification by chromatography afforded 26 in 37% yield; m.p. 235–240 °C; UV-Vis
(MeOH): λmax (log ε) = 558 nm (4.87); IR (KBr, cm-1): ῦ = 3441br, 2944m, 1718m, 1648m,
1
1590s, 1467m, 1414m, 1338m, 1275m, 1181m; Rf 0.46 (ACN/DCM/H2O 10:1:1); H NMR
(500 MHz, CDCl3):
δ = 8.22 (dd, J = 7.8, 1.0 Hz, 1 H, 3″-H), 7.79 (dt, J = 7.5, 1.0 Hz, 1 H,
5″-H), 7.72 (dt, J = 7.7, 1.0 Hz, 1 H, 4″-H), 7.31 (dd, J = 7.4, 1.0 Hz, 1 H, 6″-H), 7.14, 7.05
(2 x d, J = 9.5 Hz, 2 H, 1′-H, 8′-H), 6.90, 6.84 (2 x dd, J = 9.5, 2.0 Hz, 2 H, 2′-H, 7′-H), 6.81
(d, J = 2.0 Hz, 2 H, 4′-H, 5′-H), 5.22 (t, J = 3.4 Hz, 1 H, 12-H), 4.42 (dd, J = 10.6, 5.7 Hz,
1 H, 3-H), 3.64 (q, J = 6.9 Hz, 4 H, N(CH2CH3)2), 3.63 (q, J = 6.9 Hz, 4 H, N′(CH2CH3)2),
3.59 (s, 3 H, OMe), 2.81 (dd, J = 13.8, 3.7 Hz, 1 H, 18-H), 1.92 (ddd, J = 14.3, 14.3, 3.8 Hz,
1 H, 16-Ha), 1.82 (ddd, J = 18.6, 11.2, 3.1 Hz, 1 H, 11-Ha), 1.74 (ddd, J = 18.6, 6.3, 4.0 Hz,
1 H, 11-Hb), 1.65 (ddd, J = 13.9, 13.9, 4.4 Hz, 1 H, 22-Ha), 1.61–1.50 (m, 3 H, 16-Hb, 15-Ha,
19-Ha), 1.50–1.38 (m, 4 H, 22-Hb, 1-Ha, 6-Ha, 9-H), 1.38–1.12 (m, 7 H, 7-H2, 21-H2, 2-H2,
6-Hb), 1.32 (t, J = 7.0 Hz, 6 H, N(CH2CH3)2), 1.31 (t, J = 7.0 Hz, 6 H, N′(CH2CH3)2), 1.09
(mc, 1 H, 19-Hb), 1.04 (s, 3 H, 27-H3), 0.99 (mc, 1 H, 15-Hb), 0.89 (s, 3 H, 30-H3), 0.88–0.83
(m, 1 H, 1-Hb), 0.86 (s, 3 H, 29-H3), 0.83 (s, 3 H, 25-H3), 0.71–0.65 (m, 1 H, 5-H), 0.69 (s,
13
3 H, 23-H3), 0.67 (s, 3 H, 26-H3), 0.61 (s, 3 H, 24-H3) ppm; C NMR (125 MHz, CDCl3):
δ
= 178.2 (C-28), 165.2 (CO-Rhd), 158.7 (C-9′), 157.9, 157.7 (C-4a′, C-10a′), 155.6, 155.4
(C-3′, C-6′), 143.8 (C-13), 133.0 (C-1″), 132.8 (C-5″), 131.5, 131.2 (C-1′, C-8′), 131.1 (C-2″),
131.0 (C-3″), 130.4 (C-4″), 130.3 (C-6″), 122.0 (C-12), 114.3, 114.1 (C-2′, C-7′), 113.6
(C-8a′, C-9a′), 96.4 (C-4′, C-5′), 82.8 (C-3), 55.2 (C-5), 51.5 (OMe), 47.5 (C-9), 46.7 (C-17),
46.3, 46.2 (N(CH2CH3)2, N′(CH2CH3)2), 45.8 (C-19), 41.6 (C-14), 41.2 (C-18), 39.2 (C-8),
38.0 (C-1), 37.7 (C-4), 36.8 (C-10), 33.8 (C-21), 33.0 (C-29), 32.5 (C-7), 32.3 (C-22), 30.6
(C-20), 27.9 (C-23), 27.6 (C-15), 25.8 (C-27), 23.6 (C-30), 23.3 (C-11), 23.0 (C-2, C-16),
18.1 (C-6), 16.8 (C-26), 16.5 (C-24), 15.3 (C-25), 12.6 (N(CH2CH3)2, N′(CH2CH3)2) ppm;
MS (ESI, MeOH): m/z (%) 896 (100) [M-Cl]+; C59H79ClN2O5 (931.72).
4.3.23. 9-(2-(29-Methoxy-11,29-dioxo-20ß-olean-12-en-3ß-oxycarbonyl)phenyl)-3,6-
bis(diethylamino)-xanthylium chloride (27)
Following GP5 to a solution of rhodamine B (0.50 g, 1.04 mmol, 1 eq.) in dry DCM (10 mL),
oxalyl chloride (0.53 g, 0.36 mL, 4.18 mmol, 4 eq.) was added. After work-up as described, to
14

ACCEPTED MANUSCRIPT
a solution of the residue in dry DCM (15 mL), 7 (1.70 g, 3.52 mmol, 3 eq.), NEt3 (0.14 g,
0.20 mL, 1.40 mmol, 1.5 eq.) and DMAP (5 mol-%) were added. Work-up as described and
purification by chromatography afforded 27 in 35% yield; m.p. 235–240 °C; UV-Vis
(MeOH): λmax (log ε) = 558 nm (4.56); ); IR (KBr, cm-1): ῦ = 3447br, 2971m, 1718m, 1648m,
1
1590s, 1466m, 1414m, 1338m, 1276m, 1181m; Rf 0.46 (ACN/DCM/H2O 10:1:1); H NMR
(500 MHz, CDCl3):
δ = 8.22 (dd, J = 7.8, 1.2 Hz, 1 H, 3″-H), 7.80 (dt, J = 7.6, 1.3 Hz, 1 H,
5″-H), 7.72 (dt, J = 7.7, 1.2 Hz, 1 H, 4″-H), 7.32 (dd, J = 7.6, 1.1 Hz, 1 H, 6″-H), 7.16, 7.06
(2 x d, J = 9.5 Hz, 2 H, 1′-H, 8′-H), 6.91, 6.85 (2 x dd, J = 9.5, 2.4 Hz, 2 H, 2′-H, 7′-H), 6.80
(mc, 2 H, 4′-H, 5′-H), 5.61 (s, 1 H, 12-H), 4.44 (dd, J = 11.6, 4.8 Hz, 1 H, 3-H), 3.66 (q,
J = 7.0 Hz, 4 H, N(CH2CH3)2), 3.65 (s, 3 H, OMe), 3.63 (q, J = 7.0 Hz, 4 H, N′(CH2CH3)2),
2.62 (ddd, J = 13.7, 3.5, 3.5 Hz, 1 H, 1-Ha), 2.22 (s, 1 H, 9-H), 2.05 (dd, J = 13.4, 3.8 Hz, 1 H,
18-H), 2.02–1.93 (m, 2 H, 16-Ha, 21-Ha), 1.86 (ddd, J = 14.5, 4.0, 2.5 Hz, 1 H, 19-Ha), 1.77
(ddd, J = 13.7, 13.7, 4.4 Hz, 1 H, 15-Ha), 1.62–1.51 (m, 2 H, 7-Ha, 19-Hb), 1.48 (mc, 1 H,
6-Ha), 1.39–1.24 (m, 5 H, 22-H2, 7-Hb, 21-Hb, 6-Hb), 1.32 (t, J = 7.0 Hz, 6 H, N(CH2CH3)2),
1.31 (t, J = 7.0 Hz, 6 H, N′(CH2CH3)2), 1.27 (s, 3 H, 27-H3), 1.24–1.11 (m, 3 H, 2-H2, 15-Hb),
1.10 (s, 3 H, 29-H3), 1.06 (s, 3 H, 26-H3), 1.02 (s, 3 H, 25-H3), 1.01–0.95 (m, 1 H, 16-Hb),
0.84 (ddd, J = 13.7, 13.7, 3.5 Hz, 1 H, 1-Hb), 0.76 (s, 3 H, 28-H3), 0.71 (s, 3 H, 23-H3), 0.65
(dd, J = 12.1, 2.0 Hz, 1 H, 5-H), 0.55 (s, 3 H, 24-H3) ppm; 13C NMR (125 MHz, CDCl3):
δ
= 200.0 (C-11), 176.9 (C-30), 169.7 (C-13), 165.3 (CO-Rhd), 158.6 (C-9′), 157.9, 157.7
(C-4a′, C-10a′), 155.6, 155.4 (C-3′, C-6′), 132.8 (C-1″), 132.7 (C-5″), 131.5, 131.2 (C-1′,
C-8′), 131.1 (C-2″), 131.0 (C-3″), 130.4 (C-4″), 130.3 (C-6″), 128.3 (C-12), 114.3, 114.2
(C-2′, C-7′), 113.6 (C-8a′, C-9a′), 96.3 (C-4′, C-5′), 82.5 (C-3), 61.5 (C-9), 54.9 (C-5), 51.7
(OMe), 48.4 (C-18), 46.3, 46.2 (N(CH2CH3)2, N′(CH2CH3)2), 45.3 (C-8), 44.0 (C-20), 43.2
(C-14), 41.1 (C-19), 38.6 (C-1), 38.0 (C-4), 37.7 (C-22), 36.8 (C-10), 32.5 (C-7), 31.8 (C-17),
31.1 (C-21), 28.5 (C-28), 28.3 (C-29), 28.0 (C-23), 26.4 (C-15), 26.3 (C-16), 23.2 (C-27),
22.9 (C-2), 18.6 (C-26), 17.2 (C-6), 16.4 (C-24), 16.3 (C-25), 12.6 (N(CH2CH3)2,
N′(CH2CH3)2) ppm; MS (ESI, MeOH): m/z (%) 910 (100) [M-Cl]+; C59H77ClN2O6 (945.71).
4.3.24. 9-(2-(28-Methoxy-28-oxo-lup-20(29)-en-3ß-oxycarbonyl)phenyl)-3,6-
bis(diethylamino)-xanthylium chloride (28)
Following GP5 to a solution of rhodamine B (0.56 g, 1.16 mmol, 1 eq.) in dry DCM (10 mL),
oxalyl chloride (0.58 g, 0.40 mL, 4.64 mmol, 4 eq.) was added. After work-up as described, to
a solution of the residue in dry DCM (10 mL), 8 (0.44 g, 0.90 mmol, 1 eq.), NEt3 (0.13 g,
0.20 mL, 1.35 mmol, 1.5 eq.) and DMAP (5 mol-%) were added. Work-up as described and
15

ACCEPTED MANUSCRIPT
purification by chromatography afforded 28 in 40% yield.; m.p. 265–270 °C; UV-Vis
(MeOH): λmax (log ε) = 640 nm (4.73), 278 (4.91); IR (KBr, cm-1): ῦ = 3441br, 2940m,
1717m, 1648m, 1590s, 1466m, 1413m, 1337m, 1274m, 1180m; Rf 0.46 (ACN/DCM/H2O
1
10:1:1); H NMR (500 MHz, CDCl3):
δ = 8.22 (dd, J = 7.9, 1.0 Hz, 1 H, 3″-H), 7.79 (dt,
J = 7.6, 1.3 Hz, 1 H, 5″-H), 7.72 (dt, J = 7.8, 1.2 Hz, 1 H, 4″-H), 7.31 (dd, J = 7.6, 1.0 Hz,
1 H, 6″-H), 7.14, 7.05 (2 x d, J = 9.5 Hz, 2 H, 1′-H, 8′-H), 6.90, 6.84 (2 x dd, J = 9.5, 2.5 Hz,
2 H, 2′-H, 7′-H), 6.81 (mc, 2 H, 4′-H, 5′-H), 4.69 (mc, 1 H, 29-Ha), 4.55 (mc, 1 H, 29-Hb),
4.40 (dd, J = 9.0, 7.3 Hz, 1 H, 3-H), 3.64 (q, J = 7.4 Hz, 4 H, N(CH2CH3)2), 3.62 (q,
J = 7.4 Hz, 4 H, N′(CH2CH3)2), 3.63 (s, 3 H, OMe), 2.94 (ddd, J = 11.1, 10.9, 4.5 Hz, 1 H,
19-H), 2.19 (mc, 1 H, 16-Ha), 2.14 (mc, 1 H, 13-H), 1.90–1.79 (m, 2 H, 22-Ha, 21-Ha), 1.68–
1.62 (m, 1 H, 12-Ha), 1.66 (s, 3 H, 30-H3), 1.57–1.47 (m, 2 H, 1-Ha,18-H), 1.31 (mc, 12 H,
N(CH2CH3)2, N′(CH2CH3)2), 1.42–1.20 (m, 11 H, 6-H2, 11-H2, 2-H2, 21-Hb, 15-Ha, 16-Hb,
22-Hb, 9-H), 1.08 (mc, 1 H, 15-Hb), 0.95 (mc, 1 H, 12-Hb), 0.87 (s, 3 H, 27-H3), 0.85 (s, 3 H,
26-H3), 0.78 (mc, 1 H, 1-Hb), 0.73 (s, 3 H, 25-H3), 0.66 (s, 3 H, 23-H3), 0.63 (mc, 1 H, 5-H),
13
0.56 (s, 3 H, 24-H3) ppm; C NMR (125 MHz, CDCl3):
δ = 176.6 (C-28), 165.2 (CO-Rhd),
158.7 (C-9′), 157.9, 157.7 (C-4a′, C-10a′), 155.6, 155.4 (C-3′, C-6′), 150.5 (C-20), 132.9
(C-1″), 132.7 (C-5″), 131.5, 131.1 (C-1′, C-8′), 131.2 (C-2″), 131.1 (C-3″), 130.4 (C-4″),
130.3 (C-6″), 114.3, 114.1 (C-2′, C-7′), 113.6 (C-8a′, C-9a′), 109.5 (C-29), 96.4, 96.3 (C-4′,
C-5′), 82.8 (C-3), 56.5 (C-17), 55.3 (C-5), 51.2 (OMe), 50.4 (C-9), 49.4 (C-18), 46.9 (C-19),
46.2, 46.1 (N(CH2CH3)2, N′(CH2CH3)2), 42.3 (C-14), 40.6 (C-8), 38.3 (C-1), 38.2 (C-13),
37.8 (C-4), 37.0 (C-10), 36.9 (C-22), 34.1 (C-7), 32.1 (C-16), 30.6 (C-21), 29.6 (C-15), 27.9
(C-23), 25.4 (C-12), 23.1 (C-2), 20.8 (C-11), 19.3 (C-30), 18.1 (C-6), 16.3 (C-24), 16.1
(C-25), 15.9 (C-26), 14.6 (C-27), 12.7, 12.6 (N(CH2CH3)2, N′(CH2CH3)2) ppm; MS (ESI,
MeOH): m/z (%) 896 (100) [M-Cl]+; C59H79ClN2O5 (931.72).
4.3.25. 9-(2-(28-Benzyloxy-28-oxo-urs-12-en-3ß-oxycarbonyl)phenyl)-3,6-bis(diethylamino)-
xanthylium chloride (29)
Following GP5 to a solution of rhodamine B (0.58 g, 1.23 mmol, 1 eq.) in dry DCM (10 mL),
oxalyl chloride (0.62 g, 0.42 mL, 4.91 mmol, 4 eq.) was added. After work-up as described, to
a solution of the residue in dry DCM (10 mL), 9 (0.68 g, 1.26 mmol, 1 eq.), NEt3 (0.19 g,
0.26 mL, 1.88 mmol, 1.5 eq.) and DMAP (5 mol-%) were added. Work-up as described and
purification by chromatography afforded 29 in 54% yield; m.p. 205–210 °C; UV-Vis
(MeOH): λmax (log ε) = 558 nm (5.04); IR (KBr, cm-1): ῦ = 3442br, 2926m, 1717m, 1647m,
1
1590s, 1467m, 1413m, 1338m, 1274m, 1180m; Rf 0.46 (ACN/DCM/H2O 10:1:1); H NMR
16

ACCEPTED MANUSCRIPT
(500 MHz, CDCl3):
δ
= 8.22 (dd, J = 7.9, 1.0 Hz, 1 H, 3″-H), 7.78 (dt, J = 7.6, 1.3 Hz, 1 H,
5″-H), 7.71 (dt, J = 7.6, 1.2 Hz, 1 H, 4″-H), 7.34–7.24 (m, 6 H, Ph, 6″-H), 7.14, 7.05 (2 x d,
J = 9.5 Hz, 2 H, 1′-H, 8′-H), 6.92, 6.84 (2 x dd, J = 9.5, 2.3 Hz, 2 H, 2′-H, 7′-H), 6.79 (d,
J = 2.3 Hz, 2 H, 4′-H, 5′-H), 5.16 (t, J = 3.4 Hz, 1 H, 12-H), 5.06 (d, J = 12.4 Hz, 1 H,
CHaPh), 4.94 (d, J = 12.4 Hz, 1 H, CHbPh), 4.42 (dd, J = 10.5, 5.8 Hz, 1 H, 3-H), 3.65 (q,
J = 7.0 Hz, 4 H, N(CH2CH3)2), 3.63 (q, J = 7.0 Hz, 4 H, N′(CH2CH3)2), 2.21 (d, J = 11.2 Hz,
1 H, 18-H), 1.96 (ddd, J = 13.3, 13.3, 4.4 Hz, 1 H, 16-Ha), 1.81–1.62 (m, 5 H, 11-H2, 15-Ha,
16-Hb, 22-Ha), 1.57 (ddd, J = 13.3, 13.3, 4.0 Hz, 1 H, 22-Hb), 1.51–1.42 (m, 2 H, 21-Ha,
1-Ha), 1.42–1.18 (m, 9 H, 6-H2, 2-H2, 7-H2, 21-Hb, 9-H, 19-H), 1.31 (t, J = 7.1 Hz, 6 H,
N(CH2CH3)2), 1.30 (t, J = 7.1 Hz, 6 H, N′(CH2CH3)2), 1.04–0.94 (m, 2 H, 15-Hb, 20-H), 0.98
(s, 3 H, 27-H3), 0.90 (d, J = 6.1 Hz, 3 H, 30-H3), 0.87 (ddd, J = 13.1, 13.1, 4.3 Hz, 1 H, 1-Hb),
0.88 (s, 3 H, 30-H3), 0.81 (s, 3 H, 25-H3), 0.80 (d, J = 7.1 Hz, 3 H, 29-H3), 0.71–0.64 (m, 1 H,
5-H), 0.68 (s, 3 H, 23-H3), 0.59 (s, 3 H, 24-H3), 0.58 (s, 3 H, 26-H3) ppm; 13C NMR
(125 MHz, CDCl3):
δ = 177.2 (C-28), 165.2 (CO-Rhd), 158.7 (C-9′), 157.9, 157.7 (C-4a′,
C-10a′), 155.6, 155.4 (C-3′, C-6′), 138.1 (C-13), 136.3 (Ci-Ph), 133.0 (C-1″), 132.7 (C-5″),
131.5, 131.2 (C-1′, C-8′), 131.1 (C-2″), 131.0 (C-3″), 130.4 (C-4″), 130.3 (C-6″), 128.4
(Cm-Ph), 128.1 (Co-Ph), 127.9 (Cp-Ph), 125.3 (C-12), 114.3, 114.1 (C-2′, C-7′), 113.6 (C-8a′,
C-9a′), 96.3 (C-4′, C-5′), 82.8 (C-3), 65.9 (CH2Ph), 55.2 (C-5), 52.8 (C-18), 48.0 (C-17), 47.4
(C-9), 46.3, 46.2 (N(CH2CH3)2, N′(CH2CH3)2), 41.9 (C-14), 39.4 (C-8), 39.0 (C-19), 38.8
(C-20), 38.2 (C-1), 37.7 (C-4), 36.7 (C-10), 36.6 (C-22), 32.8 (C-7), 30.6 (C-21), 28.0 (C-23),
27.9 (C-15), 24.1 (C-16), 23.4 (C-27), 23.2 (C-11), 23.0 (C-2), 21.1 (C-30), 18.1 (C-6), 17.0
(C-29), 16.9 (C-26), 16.5 (C-24), 15.4 (C-25), 12.7, 12.6 (N(CH2CH3)2, N′(CH2CH3)2) ppm;
MS (ESI, MeOH): m/z (%) 972 (100) [M-Cl]+; C65H83ClN2O5 (1007.82).
4.3.26. 9-(2-(28-Benzyloxy-28-oxo-olean-12-en-3ß-oxycarbonyl)phenyl)-3,6-
bis(diethylamino)-xanthylium chloride (30)
Following GP5 to a solution of rhodamine B (0.58 g, 1.21 mmol, 1 eq.) in dry DCM (10 mL),
oxalyl chloride (0.61 g, 0.42 mL, 4.84 mmol, 4 eq.) was added. After work-up as described, to
a solution of the residue in dry DCM (10 mL), 10 (0.49 g, 0.89 mmol, 1 eq.), NEt3 (0.13 g,
0.20 mL, 1.34 mmol, 1.5 eq.) and DMAP (5 mol-%) were added. Work-up as described and
purification by chromatography afforded 30 in 63% yield; m.p. 215–220 °C; UV-Vis
(MeOH): λmax (log ε) = 641 nm (5.00); IR (KBr, cm-1): ῦ = 3448br, 2940m, 1717m, 1646m,
1
1590s, 1466m, 1413m, 1339m, 1274m, 1181m; Rf 0.46 (ACN/DCM/H2O 10:1:1); H NMR
17

ACCEPTED MANUSCRIPT
(500 MHz, CDCl3):
δ
= 8.22 (dd, J = 7.9, 1.1 Hz, 1 H, 3″-H), 7.79 (dt, J = 7.5, 1.2 Hz, 1 H,
5″-H), 7.72 (dt, J = 7.7, 1.2 Hz, 1 H, 4″-H), 7.34–7.27 (m, 6 H, Ph, 6″-H), 7.14, 7.05 (2 x d,
J = 9.5 Hz, 2 H, 1′-H, 8′-H), 6.91, 6.85 (2 x dd, J = 9.5, 2.4 Hz, 2 H, 2′-H, 7′-H), 6.81 (d,
J = 2.4 Hz, 2 H, 4′-H, 5′-H), 5.22 (t, J = 3.4 Hz, 1 H, 12-H), 5.06 (d, J = 12.6 Hz, 1 H,
CHaPh), 5.01 (d, J = 12.6 Hz, 1 H, CHbPh), 4.42 (dd, J = 10.7, 5.6 Hz, 1 H, 3-H), 3.65 (q,
J = 7.1 Hz, 4 H, N(CH2CH3)2), 3.63 (q, J = 7.1 Hz, 4 H, N′(CH2CH3)2), 2.86 (dd, J = 13.8,
4.1 Hz, 1 H, 18-H), 1.93 (ddd, J = 13.6, 13.6, 4.0 Hz, 1 H, 16-Ha), 1.79–1.73 (m, 2 H, 11-H2),
1.68 (ddd, J = 13.8, 13.8, 4.4 Hz, 1 H, 22-Ha), 1.65–1.48 (m, 4 H, 16-Hb, 15-Ha, 19-Ha,
22-Hb), 1.45 (ddd, J = 13.4, 13.4, 3.5 Hz, 1 H, 1-Ha), 1.43–1.36 (m, 2 H, 6-Ha, 9-H), 1.36–
1.21 (m, 5 H, 7-Ha, 21-Ha, 2-H2, 6-Hb), 1.32 (t, J = 7.1 Hz, 6 H, N(CH2CH3)2), 1.31 (t,
J = 7.1 Hz, 6 H, N′(CH2CH3)2), 1.20–1.13 (m, 2 H, 7-Hb, 21-Hb), 1.10 (ddd, J = 13.7, 4.4,
2.0 Hz, 1 H, 19-Hb), 1.03 (s, 3 H, 27-H3), 0.98 (ddd, J = 13.9, 3.0, 3.0 Hz, 1 H, 15-Hb), 0.88
(s, 3 H, 30-H3), 0.86 (s, 3 H, 29-H3), 0.80 (s, 3 H, 25-H3), 0.69 (s, 3 H, 23-H3), 0.87–0.80 (m,
1 H, 1-Hb), 0.67 (mc, 1 H, 5-H), 0.61 (s, 3 H, 24-H3), 0.55 (s, 3 H, 26-H3) ppm ppm; 13C NMR
(125 MHz, CDCl3):
δ = 177.4 (C-28), 165.2 (CO-Rhd), 158.7 (C-9′), 157.9, 157.7 (C-4a′,
C-10a′), 155.6, 155.4 (C-3′, C-6′), 143.7 (C-13), 136.4 (Ci-Ph), 133.0 (C-1″), 132.8 (C-5″),
131.5, 131.2 (C-1′, C-8′), 131.1 (C-2″), 131.0 (C-3″), 130.4 (C-4″), 130.3 (C-6″), 128.4
(Cm-Ph), 127.9 (Co-Ph), 127.8 (Cp-Ph), 122.2 (C-12), 114.3, 114.1 (C-2′, C-7′), 113.6 (C-8a′,
C-9a′), 96.4 (C-4′, C-5′), 82.8 (C-3), 65.9 (CH2Ph), 55.2 (C-5), 47.5 (C-9), 46.7 (C-17), 46.3,
46.2 (N(CH2CH3)2, N′(CH2CH3)2), 45.8 (C-19), 41.6 (C-14), 41.3 (C-18), 39.2 (C-8), 38.0
(C-1), 37.8 (C-4), 36.8 (C-10), 33.8 (C-21), 33.0 (C-29), 32.5 (C-7), 32.3 (C-22), 30.6 (C-20),
27.9 (C-23), 27.6 (C-15), 25.7 (C-27), 23.6 (C-30), 23.3 (C-11), 23.0 (C-2, C-16), 18.1 (C-6),
16.8 (C-26), 16.5 (C-24), 15.3 (C-25), 12.7, 12.6 (N(CH2CH3)2, N′(CH2CH3)2) ppm; MS
(ESI, MeOH): m/z (%) 972 (100) [M-Cl]+; C65H83ClN2O5 (1007.82).
4.3.27. 9-(2-(29-Benzyloxy-11,29-dioxo-20ß-olean-12-en-3ß-oxycarbonyl)phenyl)-3,6-
bis(diethylamino)-xanthylium chloride (31)
Following GP5 to a solution of rhodamine B (0.46 g, 0.96 mmol, 1 eq.) in dry DCM (10 mL),
oxalyl chloride (0.48 g, 0.33 mL, 3.78 mmol, 4 eq.) was added. After work-up as described, to
a solution of the residue in dry DCM (15 mL), 11 (0.40 g, 0.71 mmol, 1 eq.), NEt3 (0.14 g,
0.20 mL, 1.40 mmol, 1.5 eq.) and DMAP (5 mol-%) were added. Work-up as described and
purification by chromatography afforded 31 in 56% yield; m.p. 225–230 °C; UV-Vis
(MeOH): λmax (log ε) = 557 nm (4.61); IR (KBr, cm-1): ῦ = 3447br, 2970m, 1717m, 1647m,
1
1590s, 1466m, 1413m, 1338m, 1275m, 1181m; Rf 0.46 (ACN/DCM/H2O 10:1:1); H NMR
18

ACCEPTED MANUSCRIPT
(500 MHz, CDCl3):
δ
= 8.22 (dd, J = 7.9, 1.1 Hz, 1 H, 3″-H), 7.80 (dt, J = 7.6, 1.2 Hz, 1 H,
5″-H), 7.73 (dt, J = 7.7, 1.1 Hz, 1 H, 4″-H), 7.38–7.27 (m, 6 H, Ph, 6″-H), 7.16, 7.06 (2 x d,
J = 9.5 Hz, 2 H, 1′-H, 8′-H), 6.92, 6.86 (2 x dd, J = 9.6, 2.4 Hz, 2 H, 2′-H, 7′-H), 6.80 (d,
J = 2.4 Hz, 2 H, 4′-H, 5′-H), 5.50 (s, 1 H, 12-H), 5.17 (d, J = 12.3 Hz, 1 H, CHaPh), 5.06 (d,
J = 12.3 Hz, 1 H, CHbPh), 4.45 (dd, J = 11.7, 4.8 Hz, 1 H, 3-H), 3.66 (q, J = 7.1 Hz, 4 H,
N(CH2CH3)2), 3.64 (q, J = 7.1 Hz, 4 H, N′(CH2CH3)2), 2.63 (ddd, J = 13.7, 3.5, 3.5 Hz, 1 H,
1-Ha), 2.21 (s, 1 H, 9-H), 2.03–1.95 (m, 3 H, 18-H, 16-Ha, 21-Ha), 1.90 (mc, 1 H, 19-Ha), 1.76
(ddd, J = 13.7, 13.7, 4.4 Hz, 1 H, 15-Ha), 1.61–1.52 (m, 2 H, 7-Ha, 19-Hb), 1.51–1.22 (m, 6 H,
6-H2, 22-H2, 7-Hb, 21-Hb), 1.32 (t, J = 7.1 Hz, 12 H, N(CH2CH3)2, N′(CH2CH3)2), 1.26 (s,
3 H, 27-H3), 1.22–1.07 (m, 3 H, 2-H2, 15-Hb), 1.12 (s, 3 H, 29-H3), 1.05 (s, 3 H, 26-H3), 1.03
(s, 3 H, 25-H3), 0.97 (mc, 1 H, 16-Hb), 0.85 (ddd, J = 13.2, 13.2, 3.4 Hz, 1 H, 1-Hb), 0.71 (s,
3 H, 28-H3), 0.70 (s, 3 H, 23-H3), 0.65 (dd, J = 12.1, 1.8 Hz, 1 H, 5-H), 0.55 (s, 3 H, 24-H3)
ppm; 13C NMR (125 MHz, CDCl3):
δ = 199.9 (C-11), 176.1 (C-30), 169.5 (C-13), 165.5
(CO-Rhd), 158.6 (C-9′), 157.9, 157.7 (C-4a′, C-10a′), 155.6, 155.5 (C-3′, C-6′), 136.1
(Ci-Ph), 132.8 (C-1″), 132.7 (C-5″), 131.5, 131.2 (C-1′, C-8′), 131.1 (C-2″), 131.0 (C-3″),
130.4 (C-4″), 130.3 (C-6″), 128.6 (Cm-Ph), 128.3 (C-12), 128.3 (Co-Ph), 128.2 (Cp-Ph), 114.3,
114.2 (C-2′, C-7′), 113.6 (C-8a′, C-9a′), 96.3 (C-4′, C-5′), 82.5 (C-3), 66.2 (CH2Ph), 61.5
(C-9), 54.9 (C-5), 48.2 (C-18), 46.3 (N(CH2CH3)2, N′(CH2CH3)2), 45.3 (C-8), 43.9 (C-20),
43.1 (C-14), 41.0 (C-19), 38.6 (C-1), 38.0 (C-4), 37.6 (C-22), 36.8 (C-10), 32.5 (C-7), 31.7
(C-17), 31.1 (C-21), 28.4 (C-28), 28.2 (C-29), 28.0 (C-23), 26.4 (C-15), 26.3 (C-16), 23.2
(C-27), 22.9 (C-2), 18.6 (C-26), 17.2 (C-6), 16.4 (C-24), 16.3 (C-25), 12.6 (N(CH2CH3)2,
N′(CH2CH3)2) ppm; MS (ESI, MeOH): m/z (%) 986 (100) [M-Cl]+; C65H81ClN2O6 (1021.80).
4.3.28. 9-(2-(28-Benzyloxy-28-oxo-lup-20(29)-en-3ß-oxycarbonyl)phenyl)-3,6-
bis(diethylamino)-xanthylium chloride (32)
Following GP5 to a solution of rhodamine B (0.58 g, 1.21 mmol, 1 eq.) in dry DCM (10 mL),
oxalyl chloride (0.61 g, 0.42 mL, 4.84 mmol, 4 eq.) was added. After work-up as described, to
a solution of the residue in dry DCM (10 mL), 12 (0.50 g, 0.89 mmol, 1 eq.), NEt3 (0.13 g,
0.20 mL, 1.35 mmol, 1.5 eq.) and DMAP (5 mol-%) were added. Work-up as described and
purification by chromatography afforded 32 in 64% yield; m.p. 205–210 °C; UV-Vis
(MeOH): λmax (log ε) = 640 nm (5.00), 278 (4.91); IR (KBr, cm-1): ῦ = 3425br, 2940m,
1716m, 1647m, 1590s, 1466m, 1413m, 1337m, 1274m, 1180m; Rf 0.46 (ACN/DCM/H2O
1
10:1:1); H NMR (500 MHz, CDCl3):
δ
= 8.21 (dd, J = 7.9, 0.9 Hz, 1 H, 3″-H), 7.79 (dt,
19

ACCEPTED MANUSCRIPT
J = 7.5, 1.2 Hz, 1 H, 5″-H), 7.71 (dt, J = 7.7, 1.1 Hz, 1 H, 4″-H), 7.36–7.25 (m, 6 H, Ph,
6″-H), 7.14, 7.05 (2 x d, J = 9.5 Hz, 2 H, 1′-H, 8′-H), 6.90, 6.84 (2 x dd, J = 9.5, 2.2 Hz, 2 H,
2′-H, 7′-H), 6.80 (d, J = 2.2 Hz, 2 H, 4′-H, 5′-H), 5.11 (d, J = 12.2 Hz, 1 H, CHaPh), 5.05 (d,
J = 12.2 Hz, 1 H, CHbPh), 4.67 (mc, 1 H, 29-Ha), 4.55 (mc, 1 H, 29-Hb), 4.39 (dd, J = 8.9,
7.5 Hz, 1 H, 3-H), 3.65 (q, J = 7.1 Hz, 4 H, N(CH2CH3)2), 3.62 (q, J = 7.1 Hz, 4 H,
N′(CH2CH3)2), 2.97 (ddd, J = 10.9, 10.9, 4.6 Hz, 1 H, 19-H), 2.23 (ddd, J = 12.5, 12.5,
3.1 Hz, 1 H, 16-Ha), 2.23 (ddd, J = 12.2, 12.2, 3.5 Hz, 1 H, 13-H), 1.90–1.77 (m, 2 H, 22-Ha,
21-Ha), 1.66–1.59 (m, 1 H, 12-Ha), 1.63 (s, 3 H, 30-H3), 1.54 (dd, J = 11.3, 4.7 Hz, 1 H,
18-H), 1.48 (mc, 1 H, 1-Ha), 1.31 (t, J = 7.1 Hz, 6 H, N(CH2CH3)2), 1.30 (t, J = 7.1 Hz, 6 H,
N′(CH2CH3)2), 1.42–1.19 (m, 11 H, 22-Hb, 21-Hb, 6-H2, 16-Hb, 11-Ha, 2-H2, 15-Ha, 7-H2),
1.16–1.09 (m, 2 H, 11-Hb, 9-H), 1.03 (mc, 1 H, 15-Hb), 0.98–0.89 (m, 1 H, 12-Hb), 0.84 (s,
3 H, 27-H3), 0.81–0.73 (m, 1 H, 1-Hb), 0.71 (s, 3 H, 25-H3), 0.70 (s, 3 H, 26-H3), 0.65 (s, 3 H,
13
23-H3), 0.61 (dd, J = 5.1, 2.8 Hz, 1 H, 5-H), 0.55 (s, 3 H, 24-H3) ppm; C NMR (125 MHz,
CDCl3):
δ = 175.7 (C-28), 165.2 (CO-Rhd), 158.7 (C-9′), 157.9, 157.7 (C-4a′, C-10a′), 155.6,
155.4 (C-3′, C-6′), 150.5 (C-20), 136.4 (Ci-Ph), 132.9 (C-1″), 132.7 (C-5″), 131.5, 131.2
(C-1′, C-8′), 131.1 (C-2″), 131.0 (C-3″), 130.4 (C-4″), 130.3 (C-6″), 128.4 (Cm-Ph), 128.2
(Co-Ph), 128.0 (Cp-Ph), 114.3, 114.1 (C-2′, C-7′), 113.6 (C-8a′, C-9a′), 109.5 (C- 29), 96.4,
96.3 (C-4′, C-5′), 82.8 (C-3), 65.7 (CH2Ph), 56.5 (C-17), 55.3 (C-5), 50.4 (C-9), 49.4 (C-18),
46.9 (C-19), 46.2, 46.1 (N(CH2CH3)2, N′(CH2CH3)2), 42.3 (C-14), 40.6 (C-8), 38.3 (C-1),
38.1 (C-13), 37.8 (C-4), 37.0 (C-10), 36.9 (C-22), 34.1 (C-7), 32.0 (C-16), 30.5 (C-21), 29.5
(C-15), 27.9 (C-23), 25.4 (C-12), 23.1 (C-2), 20.8 (C-11), 19.3 (C-30), 18.0 (C-6), 16.3
(C-24), 16.1 (C-25), 15.8 (C-26), 14.5 (C-27), 12.7, 12.6 (N(CH2CH3)2, N′(CH2CH3)2) ppm;
MS (ESI, MeOH): m/z (%) 972 (100) [M-Cl]+; C65H83ClN2O5 (1007.82).
4.3.29. 9-(2-(28-Benzylamino-28-oxo-urs-12-en-3ß-oxycarbonyl)phenyl)-3,6-
bis(diethylamino)-xanthylium chloride (33)
Following GP5 to a solution of rhodamine B (0.59 g, 1.23 mmol, 1 eq.) in dry DCM (12 mL),
oxalyl chloride (0.62 g, 0.42 mL, 4.90 mmol, 4 eq.) was added. After work-up as described, to
a solution of the residue in dry DCM (12 mL), 21 (0.58 g, 1.06 mmol, 1 eq.), NEt3 (0.16 g,
0.22 mL, 1.59 mmol, 1.5 eq.) and DMAP (5 mol-%) were added. Work-up as described and
purification by chromatography afforded 33 in 67% yield; m.p. 234–238 °C; UV-Vis
(MeOH): λmax (log ε) = 641 nm (5.00); IR (KBr, cm-1): ῦ = 3442br, 2925m, 1715m, 1647m,
1
1589s, 1467m, 1413m, 1337m, 1274m, 1180m; Rf 0.46 (ACN/DCM/H2O 10:1:1); H NMR
(500 MHz, CDCl3):
δ
= 8.22 (dd, J = 7.8, 1.1 Hz, 1 H, 3″-H), 7.79 (dt, J = 7.6, 1.3 Hz, 1 H,
20

ACCEPTED MANUSCRIPT
5″-H), 7.72 (dt, J = 7.7, 1.2 Hz, 1 H, 4″-H), 7.33–7.19 (m, 6 H, Ph, 6″-H), 7.14, 7.05 (2 x d,
J = 9.5 Hz, 2 H, 1′-H, 8′-H), 6.92, 6.84 (2 x dd, J = 9.5, 2.4 Hz, 2 H, 2′-H, 7′-H), 6.82 (d,
J = 2.4 Hz, 2 H, 4′-H, 5′-H), 6.12 (mc, 1 H, NH), 5.16 (t, J = 3.4 Hz, 1 H, 12-H), 4.51 (dd,
J = 14.5, 6.0 Hz, 1 H, CHaPh), 4.43 (dd, J = 10.8, 5.5 Hz, 1 H, 3-H), 4.14 (dd, J = 14.5,
4.4 Hz, 1 H, CHbPh), 3.66 (q, J = 7.0 Hz, 4 H, N′(CH2CH3)2), 3.64 (q, J = 7.0 Hz, 4 H,
N″(CH2CH3)2), 1.94 (ddd, J = 13.6, 13.6, 4.2 Hz, 1 H, 16-Ha), 1.90–1.68 (m, 5 H, 22-Ha,
18-H, 11-H2, 16-Hb), 1.64 (ddd, J = 13.9, 13.9, 4.5 Hz, 1 H, 15-Ha), 1.51–1.44 (m, 3 H, 21-Ha,
22-Hb, 1-Ha), 1.43–1.35 (m, 4 H, 6-Ha, 7-Ha, 19-H, 9-H), 1.34–1.19 (m, 5 H, 21-Hb, 6-Hb,
2-H2, 7-Hb), 1.32 (t, J = 7.0 Hz, 6 H, N′(CH2CH3)2), 1.30 (t, J = 7.0 Hz, 6 H, N″(CH2CH3)2),
1.03–0.97 (m, 1 H, 15-Hb), 0.99 (s, 3 H, 27-H3), 0.95–0.83 (m, 2 H, 20-H, 1-Hb), 0.91 (s, 3 H,
30-H3), 0.80 (s, 6 H, 25-H3, 23-H3), 0.69–0.63 (m, 1 H, 5-H), 0.68 (s, 3 H, 24-H3), 0.64 (s,
3 H, 29-H3), 0.59 (s, 3 H, 26-H3) ppm; 13C NMR (125 MHz, CDCl3):
δ = 177.7 (C-28), 165.2
(CO-Rhd), 158.6 (C-9′), 157.9, 157.7 (C-4a′, C-10a′), 155.6, 155.4 (C-3′, C-6′), 139.7 (C-13),
138.3 (Ci-Ph), 133.0 (C-1″), 132.7 (C-5″), 131.5, 131.1 (C-1′, C-8′), 131.2 (C-2″), 131.0
(C-3″), 130.4 (C-4″), 130.3 (C-6″), 128.6 (Cm-Ph), 127.9 (Co-Ph), 127.3 (Cp-Ph), 125.4
(C-12), 114.3, 114.1 (C-2′, C-7′), 113.6 (C-8a′, C-9a′), 96.4 (C-4′, C-5′), 82.6 (C-3), 55.1
(C-5), 55.9 (C-18), 47.7 (C-17), 47.4 (C-9), 46.3, 46.2 (N′(CH2CH3)2, N″(CH2CH3)2), 43.6
(CH2Ph), 42.4 (C-14), 39.7 (C-19), 39.4 (C-8), 39.0 (C-20), 38.2 (C-1), 37.7 (C-4), 37.2
(C-22), 36.7 (C-10), 32.6 (C-7), 30.8 (C-21), 28.0 (C-23), 27.8 (C-15), 24.8 (C-16), 23.2
(C-11), 23.1 (C-27), 23.0 (C-2), 21.1 (C-30), 18.0 (C-6), 17.2 (C-29), 16.9 (C-26), 16.5
(C-24), 15.4 (C-25), 12.7, 12.6 (N′(CH2CH3)2, N″(CH2CH3)2) ppm; MS (ESI, MeOH): m/z
(%) 971 (100) [M-Cl]+; C65H84ClN3O4 (1006.82).
4.3.30. 9-(2-(28-Benzylamino-28-oxo-olean-12-en-3ß-oxycarbonyl)phenyl)-3,6-
bis(diethylamino)-xanthylium chloride (34)
Following GP5 to a solution of rhodamine B (0.58 g, 1.21 mmol, 1 eq.) in dry DCM (12 mL),
oxalyl chloride (0.61 g, 0.42 mL, 4.84 mmol, 4 eq.) was added. After work-up as described, to
a solution of the residue in dry DCM (10 mL), 22 (0.55 g, 1.01 mmol, 1 eq.), NEt3 (0.15 g,
0.21 mL, 1.51 mmol, 1.5 eq.) and DMAP (5 mol-%) were added. Work-up as described and
purification by chromatography afforded 34 in 64% yield; m.p. 235–238 °C; UV-Vis
(MeOH): λmax (log ε) = 641 nm (4.81); IR (KBr, cm-1): ῦ = 3448br, 2928m, 1713m, 1647m,
1
1590s, 1466m, 1413m, 1337m, 1274m, 1180m; Rf 0.46 (ACN/DCM/H2O 10:1:1); H NMR
(500 MHz, CDCl3):
δ
= 8.22 (dd, J = 7.9, 1.0 Hz, 1 H, 3″-H), 7.79 (dt, J = 7.5, 1.1 Hz, 1 H,
21

ACCEPTED MANUSCRIPT
5″-H), 7.72 (dt, J = 7.7, 1.0 Hz, 1 H, 4″-H), 7.33–7.20 (m, 6 H, Ph, 6″-H), 7.14, 7.05 (2 x d,
J = 9.5 Hz, 2 H, 1′-H, 8′-H), 6.91, 6.84 (2 x dd, J = 9.5, 2.3 Hz, 2 H, 2′-H, 7′-H), 6.81 (d,
J = 2.3 Hz, 2 H, 4′-H, 5′-H), 6.17 (dd, J = 6.3, 4.4 Hz, 1 H, NH), 5.25 (t, J = 3.5 Hz, 1 H,
12-H), 4.58 (dd, J = 14.7, 6.3 Hz, 1 H, CHaPh), 4.42 (dd, J = 10.8, 5.5 Hz, 1 H, 3-H), 4.11
(dd, J = 14.7, 4.3 Hz, 1 H, CHbPh), 3.65 (q, J = 7.1 Hz, 4 H, N′(CH2CH3)2), 3.63 (q,
J = 7.1 Hz, 4 H, N″(CH2CH3)2), 2.51 (dd, J = 12.9, 3.8 Hz, 1 H, 18-H), 1.94 (ddd, J = 13.7,
13.7, 3.5 Hz, 1 H, 16-Ha), 1.76–1.67 (m, 4 H, 11-H2, 22-Ha, 19-Ha), 1.66–1.56 (m, 2 H,
16-Hb, 22-Hb), 1.52 (ddd, J = 13.8, 13.8, 3.8 Hz, 1 H, 15-Ha), 1.47–1.38 (m, 3 H, 1-Ha, 6-Ha,
9-H), 1.37–1.23 (m, 5 H, 7-Ha, 21-Ha, 2-H2, 6-Hb), 1.31 (t, J = 7.0 Hz, 6 H, N′(CH2CH3)2),
1.30 (t, J = 7.0 Hz, 6 H, N″(CH2CH3)2), 1.22–1.15 (m, 2 H, 7-Hb, 21-Hb), 1.12 (mc, 1 H,
19-Hb), 1.05 (s, 3 H, 27-H3), 0.98 (mc, 1 H, 15-Hb), 0.90–0.80 (m, 1 H, 1-Hb), 0.86 (s, 6 H,
29-H3, 30-H3), 0.79 (s, 3 H, 25-H3), 0.69 (s, 3 H, 23-H3), 0.67 (mc, 1 H, 5-H), 0.62 (s, 3 H,
24-H3), 0.61 (s, 3 H, 26-H3) ppm; 13C NMR (125 MHz, CDCl3):
δ = 177.9 (C-28), 165.1
(CO-Rhd), 158.7 (C-9′), 157.9, 157.7 (C-4a′, C-10a′), 155.6, 155.4 (C-3′, C-6′), 144.8 (C-13),
138.4 (Ci-Ph), 133.0 (C-1″), 132.8 (C-5″), 131.4, 131.1 (C-1′, C-8′), 131.1 (C-2″), 131.0
(C-3″), 130.4 (C-4″), 130.3 (C-6″), 128.6 (Cm-Ph), 127.7 (Co-Ph), 127.3 (Cp-Ph), 122.6
(C-12), 114.3, 114.1 (C-2′, C-7′), 113.6 (C-8a′, C-9a′), 96.4 (C-4′, C-5′), 82.7 (C-3), 55.1
(C-5), 47.4 (C-9), 46.6 (C-19), 46.3 (C-17), 46.3, 46.2 (N′(CH2CH3)2, N″(CH2CH3)2), 43.5
(CH2Ph), 42.2 (C-18), 41.9 (C-14), 39.3 (C-8), 38.0 (C-1), 37.7 (C-4), 36.7 (C-10), 34.1
(C-21), 32.9 (C-29), 32.6 (C-22), 32.2 (C-7), 30.7 (C-20), 27.9 (C-23), 27.3 (C-15), 25.6
(C-27), 23.7 (C-16), 23.6 (C-30), 23.4 (C-11), 23.0 (C-2), 18.0 (C-6), 16.8 (C-26), 16.5
(C-24), 15.3 (C-25), 12.6 (N′(CH2CH3)2, N″(CH2CH3)2) ppm; MS (ESI, MeOH): m/z (%) 971
(100) [M-Cl]+; C65H84ClN3O4 (1006.82).
4.3.31. 9-(2-(29-Benzylamino-11,29-dioxo-20ß-olean-12-en-3ß-oxycarbonyl)phenyl)-3,6-
bis(diethylamino)-xanthylium chloride (35)
Following GP5 to a solution of rhodamine B (0.56 g, 1.16 mmol, 1 eq.) in dry DCM (10 mL),
oxalyl chloride (0.58 g, 0.40 mL, 4.64 mmol, 4 eq.) was added. After work-up as described, to
a solution of the residue in dry DCM (15 mL), 23 (0.51 g, 0.89 mmol, 1 eq.), NEt3 (0.13 g,
0.20 mL, 1.40 mmol, 1.5 eq.) and DMAP (5 mol-%) were added. Work-up as described and
purification by chromatography afforded 35 in 56% yield; m.p. 200–210 °C; UV-Vis
(MeOH): λmax (log ε) = 557 nm (4.65); IR (KBr, cm-1): ῦ = 3448br, 2971m, 1717m, 1647m,
1
1590s, 1466m, 1413m, 1338m, 1275m, 1181m; Rf 0.46 (ACN/DCM/H2O 10:1:1); H NMR
22

ACCEPTED MANUSCRIPT
(500 MHz, CDCl3):
δ
= 8.22 (dd, J = 7.8, 1.2 Hz, 1 H, 3″-H), 7.78 (dt, J = 7.5, 1.3 Hz, 1 H,
5″-H), 7.72 (dt, J = 7.6, 1.2 Hz, 1 H, 4″-H), 7.34–7.20 (m, 6 H, Ph, 6″-H), 7.15, 7.05 (2 x d,
J = 9.6 Hz, 2 H, 1′-H, 8′-H), 6.85, 6.81 (2 x dd, J = 9.6, 2.4 Hz, 2 H, 2′-H, 7′-H), 6.80 (d,
J = 2.4 Hz, 2 H, 4′-H, 5′-H), 6.05 (t, J = 5.8 Hz, 1 H, NH), 5.55 (s, 1 H, 12-H), 4.50–4.40 (m,
3 H, CH2Ph, 3-H), 3.61 (mc, 8 H, N′(CH2CH3)2, N″(CH2CH3)2), 2.62 (ddd, J = 13.7, 3.3,
3.3 Hz, 1 H, 1-Ha), 2.20 (s, 1 H, 9-H), 2.00 (mc, 1 H, 18-H), 1.93–1.74 (m, 3 H, 16-Ha, 21-Ha,
19-Ha), 1.73–1.51 (m, 3 H, 15-Ha, 7-Ha, 19-Hb), 1.50–1.22 (m, 6 H, 6-H2, 22-H2, 7-Hb,
21-Hb), 1.32 (t, J = 7.0 Hz, 6 H, N′(CH2CH3)2), 1.30 (t, J = 7.0 Hz, 6 H, N″(CH2CH3)2), 1.27
(s, 3 H, 27-H3), 1.22–1.14 (m, 3 H, 2-H2, 15-Hb), 1.12 (s, 3 H, 29-H3), 1.06 (s, 3 H, 26-H3),
1.02 (s, 3 H, 25-H3), 1.01–0.78 (m, 2 H, 16-Hb, 1-Hb), 0.76 (s, 3 H, 28-H3), 0.71 (s, 3 H,
23-H3), 0.65 (mc, 1 H, 5-H), 0.55 (s, 3 H, 24-H3) ppm; 13C NMR (125 MHz, CDCl3):
δ
= 199.8 (C-11), 175.6 (C-30), 169.5 (C-13), 165.3 (CO-Rhd), 158.7 (C-9′), 158.0, 157.7
(C-4a′, C-10a′), 155.5, 155.4 (C-3′, C-6′), 138.7 (Ci-Ph), 132.8 (C-1″), 132.7 (C-5″), 131.5,
131.2 (C-1′, C-8′), 131.1 (C-2″), 131.0 (C-3″), 130.4 (C-4″), 130.2 (C-6″), 128.7 (Cm-Ph),
128.2 (C-12), 127.7 (Co-Ph), 127.4 (Cp-Ph), 114.1, 114.0 (C-2′, C-7′), 113.6 (C-8a′, C-9a′),
96.3 (C-4′, C-5′), 82.5 (C-3), 61.5 (C-9), 54.9 (C-5), 48.0 (C-18), 46.1 (N′(CH2CH3)2,
N″(CH2CH3)2), 45.2 (C-8), 43.5 (CH2Ph), 43.5 (C-20), 43.2 (C-14), 41.8 (C-19), 38.6 (C-1),
38.0 (C-4), 37.4 (C-22), 36.8 (C-10), 32.5 (C-7), 31.8 (C-17), 31.5 (C-21), 29.5 (C-29), 28.4
(C-28), 27.9 (C-23), 26.4 (C-15), 26.3 (C-16), 23.1 (C-2), 22.9 (C-27), 18.6 (C-26), 17.2
(C-6), 16.4 (C-24), 16.3 (C-25), 12.5 (N′(CH2CH3)2, N″(CH2CH3)2) ppm; MS (ESI, MeOH):
m/z (%) 985 (100) [M-Cl]+; C65H82ClN3O5 (1020.82).
4.3.32. 9-(2-(28-Benzylamino-28-oxo-lup-20(29)-en-3ß-oxycarbonyl)phenyl)-3,6-
bis(diethylamino)-xanthylium chloride (36)
Following GP5 to a solution of rhodamine B (0.58 g, 1.16 mmol, 1 eq.) in dry DCM (10 mL),
oxalyl chloride (0.62 g, 0.42 mL, 4.64 mmol, 4 eq.) was added. After work up as described, to
a solution of the residue in dry DCM (10 mL), 24 (0.46 g, 1.0 mmol, 1 eq.), NEt3 (0.15 g,
0.20 mL, 1.5 mmol, 1.5 eq.) and DMAP (5 mol-%) were added. Work up as described and
purification by chromatography afforded 36 in 84% yield; m.p. 240–245 °C; UV-Vis
(MeOH): λmax (log ε) = 641 nm (4.80); IR (KBr, cm-1): ῦ = 3446br, 2928m, 1715m, 1647m,
1
1590s, 1466m, 1413m, 1337m, 1274m, 1180m; Rf 0.46 (ACN/DCM/H2O 10:1:1); H NMR
(500 MHz, CDCl3):
δ = 8.22 (dd, J = 7.8, 1.0 Hz, 1 H, 3″-H), 7.79 (dt, J = 7.6, 1.3 Hz, 1 H,
5″-H), 7.72 (dt, J = 7.7, 1.2 Hz, 1 H, 4″-H), 7.33–7.20 (m, 6 H, Ph, 6″-H), 7.15, 7.06 (2 x d,
23

ACCEPTED MANUSCRIPT
J = 9.5 Hz, 2 H, 1′-H, 8′-H), 6.92, 6.85 (2 x dd, J = 9.5, 2.4 Hz, 2 H, 2′-H, 7′-H), 6.79 (mc,
2 H, 4′-H, 5′-H), 6.07 (dd, J = 5.9, 5.8 Hz, 1 H, NH), 4.69 (mc, 1 H, 29-Ha), 4.54 (mc, 1 H,
29-Hb), 4.45 (dd, J = 14.6, 5.9 Hz, 1 H, CHaPh), 4.40 (dd, J = 8.9, 7.6 Hz, 1 H, 3-H), 4.33
(dd, J = 14.6, 5.8 Hz, 1 H, CHbPh), 3.65 (q, J = 7.4 Hz, 4 H, N′(CH2CH3)2), 3.63 (q,
J = 7.4 Hz, 4 H, N″(CH2CH3)2), 3.13 (ddd, J = 10.9, 10.9, 4.2 Hz, 1 H, 19-H), 2.45 (ddd,
J = 12.7, 11.6, 3.3 Hz, 1 H, 13-H), 1.98–1.89 (m, 2 H, 21-Ha, 16-Ha), 1.76 (mc, 1 H, 22-Ha),
1.68–1.62 (m, 1 H, 12-Ha), 1.64 (s, 3 H, 30-H3), 1.55–1.45 (m, 3 H, 18-H, 16-Hb, 1-Ha), 1.45–
1.10 (m, 12 H, 12-H, 22-Hb, 15-Ha, 21-Hb, 6-H2, 11-H2, 2-H2, 7-H2, 9-H), 1.32 (t, J = 7.1 Hz,
6 H, N′(CH2CH3)2), 1.30 (t, J = 7.1 Hz, 6 H, N″(CH2CH3)2), 1.05 (mc, 1 H, 15-Hb), 0.95–0.85
(m, 1 H, 12-Hb), 0.86 (s, 3 H, 27-H3), 0.83 (s, 3 H, 26-H3), 0.79–0.72 (m, 1 H, 1-Hb), 0.73 (s,
13
3 H, 25-H3), 0.66 (s, 3 H, 23-H3), 0.63 (mc, 1 H, 5-H), 0.55 (s, 3 H, 24-H3) ppm; C NMR
(125 MHz, CDCl3):
δ = 175.9 (C-28), 165.2 (CO-Rhd), 158.7 (C-9′), 157.9, 157.7 (C-4a′,
C-10a′), 155.6, 155.4 (C-3′, C-6′), 151.1 (C-20), 139.3 (Ci-Ph), 132.9 (C-1″), 132.7 (C-5″),
131.5, 131.1 (C-1′, C-8′), 131.2 (C-2″), 131.1 (C-3″), 130.4 (C-4″), 130.3 (C-6″), 128.5
(Cm-Ph), 127.8 (Co-Ph), 127.2 (Cp-Ph), 114.3, 114.1 (C-2′, C-7′), 113.6 (C-8a′, C-9a′), 109.2
(C- 29), 96.3 (C-4′, C-5′), 82.8 (C-3), 55.6 (C-17), 55.3 (C-5), 50.3 (C-9), 50.1 (C-18), 46.6
(C-19), 46.3, 46.2 (N′(CH2CH3)2, N″(CH2CH3)2), 43.2 (CH2Ph), 42.4 (C-14), 40.7 (C-8), 38.4
(C-22), 38.3 (C-1), 37.8 (C-4), 37.6 (C-13), 37.0 (C-10), 34.2 (C-7), 33.7 (C-16), 30.9 (C-21),
29.4 (C-15), 27.9 (C-23), 25.5 (C-12), 23.1 (C-2), 20.9 (C-11), 19.4 (C-30), 18.1 (C-6), 16.3
(C-24), 16.1 (C-25), 16.0 (C-26), 14.5 (C-27), 12.7, 12.6 (N′(CH2CH3)2, N″(CH2CH3)2) ppm;
MS (ESI, MeOH): m/z (%) 971 (100) [M-Cl]+; C65H84ClN3O4 (1006.82).
Acknowledgments
We like to thank Dr. D. Ströhl and his team for measuring the NMR spectra, and Dr. R. Kluge
for measuring the MS spectra. The IR spectra, UV-vis spectra and optical rotations were
recorded by Ms. V. Simon, B.Sc. The cell lines were kindly provided by Dr. Th. Müller
(Dept. of Haematology/Oncology, Martin-Luther Universität Halle-Wittenberg). Financial
support by the “ScienceCampus Halle, WCH” (W13004216 to R. C.) is gratefully
acknowledged. The authors declare no conflict of interests.
Appendix A. Supplementary material
Supplementary material associated with this article can be found, in the online version, at
http://
24

ACCEPTED MANUSCRIPT
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Highlights
* Triterpenoic acids were converted into their corresponding rhodamine B derivatives
* All of the compounds were cytotoxic for a variety of human tumor cell lines.
* The most potential compound was a glycyrrhetinic acid rhodamine B benzyl amide 35.
* Cytotoxicity against human tumor cell lines was in a low-digit nano-molar range.
* Compound 35 acts as a mitocan and triggers apoptosis