Short approach towards new isocoumarins and dihydroisocoumarins and investigation of their cytotoxic activities

Article abstract of DOI:10.1515/znb-2009-0310

3-Substituted isocoumarins were prepared in a short and efficient way from 2-iodobenzoic acid and terminal alkynes in a one-pot Sonogashira reaction. Catalytic hydrogenation gave the corresponding dihydroisocoumarins. The cytotoxic activities of the resul

Full text of DOI:10.1515/znb-2009-0310

Short Approach Towards New Isocoumarins and Dihydroisocoumarins
and Investigation of their Cytotoxic Activities
Isolde Wetzel, Franz Bracher, and Ju¨rgen Krauss
Department Pharmazie – Zentrum fu¨r Pharmaforschung, Ludwig-Maximilians-Universita¨t Mu¨nchen,
Butenandtstraße 5 – 13, 81377 Mu¨nchen, Germany
Reprint requests to Dr. Ju¨rgen Krauss. Fax: +49-89-2180 77171.
E-mail: hjkra@cup.uni-muenchen.de
Z. Naturforsch. 2009, 64b, 313 – 318; received November 25, 2008
3-Substituted isocoumarins were prepared in a short and efficient way from 2-iodobenzoic acid and
terminal alkynes in a one-pot Sonogashira reaction. Catalytic hydrogenation gave the corresponding
dihydroisocoumarins. The cytotoxic activities of the resulting compounds against human leukaemia
cell line (HL 60) were determined in a MTT assay, and structure-activity relationships are discussed.
Key words: Isocoumarin, Dihydroisocoumarin, Sonogashira Reaction, Hydrogenation, Cytotoxic
Activity
Introduction
Isocoumarins are a large and structurally diverse
class of bioactive natural products with widespread
occurance in living organisms [1], and considerable
work has been published over decades about their
chemistry [2] and biology [3]. A considerable number
of natural and synthetic isocoumarins showed signi-
ficant cytotoxic and antitumor activity. Among those
are dihydroisocoumarins like AI-77-B (A), as well
as numerous isocoumarins bearing substituents at C-3
(Fig. 1). The dihydroisocoumarin AI-77-B (A) shows
in vitro cytotoxicity against human malignant A375-
S2 and human cervical cancer HeLa cells [4]. The
paraphaeosphaerins (B) recently isolated from cul-
tures of Paraphaeosphaeria quadriseptana [5] are bio-
genetically related to the cytotoxic plant metabolites
monocillin I and radicicol. NM-3 (C) is a synthetic
analog of cytogenin (E), and potentiates antineoplastic
effects of other chemotherapeutic agents and inhibits
angiogenesis [6]. This compound is in phase I clini-
cal trials. The isocoumarin 185322 (D) [7], an ana-
log of NM-3, is an inhibitor of microtubule assembly,
and induces mitotic arrest and apoptosis of multiple
myeloma cells.
Fig. 1. Structures of AI-77-B (A), paraphaeosphaerin A (B),
NM-3 (C), 185322 (D), and cytogenin (E).
pounds are oxygen substituents (mainly at C-8 and to
a lesser extent at C-6), and side chains at C-3.
Since there is a large structural diversity in these
side chains (length, branching, polarity, additional
functional groups), we intended to get more insight
into the influence of the C-3 substituents on cyto-
toxic activity. For this purpose a series of isocoumarins
and dihydroisocoumarins with different substituents at
C-3 was to be synthesized and screened for cytotoxic
activity.
In addition to the classical synthetic approaches to
the isocoumarin ring system starting from homoph-
thalic acid and related compounds [2, 3], organometal-
lic methods have been introduced a few decades ago
[10, 11]. In 1993, Kundu and Pal reported on the coup-
ling of 2-iodobenzoic acid with terminal alkynes cata-
lyzed by Pd(PPh3)2Cl2, CuI and Et3N for the prepara-
The biological activities of the abovementioned
and other isocoumarins and dihydroisocoumarins[8, 9]
make this class of compounds interesting leads for de-
velopment of new anticancer drugs. The most promi-
nent structural features found in the bioactive com-
c
0932–0776 / 09 / 0300–0313 $ 06.00 ꢀ 2009 Verlag der Zeitschrift fu¨r Naturforschung, Tu¨bingen · http://znaturforsch.com
Unauthenticated
Download Date | 4/7/16 2:38 PM

314
I. Wetzel et al. · New Isocoumarins and Dihydroisocoumarins and their Cytotoxic Activities
Scheme 1. a: Triethylamine,
ZnCl2, Pd(PPh3)2Cl2, DMF,
100 ◦C; b: H2, Pd/C, methanol,
room temp.; c: hydrazine,
EtOH, reflux.
tion of phthalides [12]. In these reactions isocoumarins zoic ester in our hands [16], we prepared the alkyne
were obtained as minor by-products. Later on Liao 5 by Sonogashira reaction of methyl 2-iodobenzoate
and Cheng described an efficient method for the syn- (1c) with 5-methylhex-1-yne under catalysis of CuI
thesis of isocoumarins from 2-iodobenzoic acid and and Pd(PPh3)2Cl2. Upon treatment with methanolic
terminal alkynes using Pd(PPh3)4 or Pd(PPh3)2Cl2, KOH the isocoumarin 2c was obtained in very low
ZnCl2 and Et3N as catalysts [13]. We adopted this yield (6 %). Thus the first variant starting from the car-
method for the preparation of our target compounds. boxylic acid 1a was found to give the highest yield,
In a recent publication it has been shown that the and was exclusively used for the syntheses of the other
Pd-phosphine complexes can be replaced by Pd on isocoumarins.
charcoal [14].
The isocoumarins 2a – d were hydrogenated under
Pd/C catalysis to give the dihydroisocoumarins 3a – d
(Scheme 1) [17].
Results
An attempt to liberate the primary amino group pro-
tected as the N-alkylphthalimide in 2e by hydrazinoly-
sis did not give the expected aminobutyl isocoumarin,
but led to the known 1,2,3,4-tetrahydro-pyrido[1,2-b]
isoquinolin-6-one (4) (Scheme 1) [18, 19].
The antibacterial and antimycotic activities of the
new compounds were determined in an agar diffusion
assay against the bacteria Escherichia coli, Staphy-
lococcus equorum, Pseudomonas antimicrobia, and
Streptococcus entericus, and the fungi Aspergillus
niger, Candida glabrata, Hypopichii burtonii, and
Yarrowia lipolytica. The compounds did not show sig-
nificant activities compared to the references tetracy-
cline and clotrimazol (data not shown) [20].
2-Iodobenzoic acid (1a) was used for Sonogashira-
type reactions under catalysis of Pd(PPh3)2Cl2 and
ZnCl2 with five terminal alkynes to give directly, due
to an intramolecular addition of the carboxylate to the
alkyne, the isocoumarins 2a –e in 41 to 95 % yield
(Scheme 1). In an alternative approach, carboxylic acid
1a was replaced by 2-iodobenzoyl chloride 1b and
reacted with 5-methylhex-1-yne under otherwise un-
changed conditions. Once again the isocoumarin 2c
was formed, albeit in lower yield (64 % compared to
99 %).
In a further variant (Scheme 2), inspired by a re-
port of Villemin and Goussu [15] and an accidental
formation of an isocoumarin from an alkynyl ben-
Finally, the cytotoxicity of the compounds was de-
termined in a MTT assay on a human leukaemia cell
line (HL 60) with cisplatin as a reference [21]. The re-
sults are shown in Table 1.
Seven of these compounds showed moderate cyto-
toxicity with IC50 values in the range of 40 – 80 µM.
We could detect no significant differences in the cy-
Scheme 2. a: Triethylamine, CuI, Pd(PPh3)2Cl2, room temp.;
b: methanol, reflux.
Unauthenticated
Download Date | 4/7/16 2:38 PM

I. Wetzel et al. · New Isocoumarins and Dihydroisocoumarins and their Cytotoxic Activities
315
Table 1. MTT assay: IC50 values against HL-60 cells.
Bu¨chi melting point B-540 apparatus and are uncorrected;
flash column chromatography (FCC): silica gel 60 (230 –
400 mesh, E. Merck, Darmstadt); HPLC: Merck Hitachi Se-
ries 7000, column: LiChroCart 250-4; LiChrospher 100
RP 18 (5µM, Merck), eluent: methanol / water 75 : 25 (com-
pound 2a and 3a: 90 : 10), detection: UV, λ = 254 nm.
Compound
IC50 (µM)
Compound
IC50 (µM)
2a
45
70
40
3a
3b
3c
3d
4
44
62
78
R
ꢀ
2b
2c
2d
> 100 (3547)
48
5
> 100 (1978)
> 100 (354)
2e
cisplatin
General procedure 1 (Sonogashira reaction)
Pd(PPh3)2Cl2 (0.10 mmol) and ZnCl2 (4.0 mmol) were
added under N2 atmosphere to a solution of aryl io-
dide (2.00 mmol), alkyne (6.0 mmol), and triethylamine
(10 mmol) in DMF (2 mL). The suspension was heated at
100 C for 24 h. The components of the suspension were
separated by flash column chromatography (n-hexane / ethyl
Table 2. Values of log P of compounds 2a – e, 3a – d and 4.
Compound
log P
6.5
Compound
log P
6.1
2a
2b
2c
2d
2e
3a
3b
3c
3d
4
◦
4.3
4.3
3.9
3.6
2.0
3.6
1.7
3.3
acetate).
General procedure 2 (catalytic hydrogenation)
totoxic potencies of the isocoumarins and the corre-
sponding dihydroisocoumarins.
20 mg of Pd on charcoal (10 %) was added to a solution
of the isocoumarin in methanol (20 mL). The suspension was
The extremely poor activities of isocoumarin 2d and stirred for 12 h under H2 atmosphere, then the catalyst was
filtered off, and the residue was washed with methanol. The
combined organic layers were evaporated, and the residue
was purified by FCC (n-hexane / ethyl acetate).
dihydroisocoumarin 3d might be explained by the cor-
relation between cytotoxicity and log P values. The
log P values of the compounds were determined by a
HPLC method by comparison with known log P values
of diphenyl ether, cinnamic acid, aniline and naphtha-
line [22], and are shown in Table 2. The inactive com-
pounds 2d and 3d have very low log P values.
3-Dodecylisochromen-1-one (2a)
Compound 2a was prepared following general procedure
1 from 2-iodobenzoic acid (496 mg, 2.00 mmol), tetradec-
1-yne (1.17 g, 6.00 mmol), triethylamine (1.0 g, 10 mmol),
Pd(PPh3)2Cl2 (70 mg, 0.10 mmol), and ZnCl2 (545 mg,
4.00 mmol) to give 560 mg (89 %) of 2a as a brown solid. –
M. p.: 48 ◦C. – C21H30O2 (314.47): calcd. C 80.21, H 9.62;
found C 80.12, H 9.95. – 1H NMR (CDCl3): δ = 0.88 (t, J =
7.1 Hz, 3 H, CH3), 1.27 (m, 18 H, 9 CH2, 3ꢀH – 11ꢀH), 1.72
(tt, J1 = J2 = 7.4 Hz, 2 H, CH2, 2ꢀ-H), 2.53 (t, J = 7.4 Hz,
CH2, 2 H, 1ꢀ-H), 6.28 (s, 1 H, arom. CH, 4-H), 7.37 (d, J =
7.8 Hz, 1 H, arom. CH, 6-H), 7.46 (ddd, J1 = J2 = 7.8 Hz,
J3 = 1.4 Hz, 1 H, arom. CH, 8-H), 7.68 (ddd, J1 = J2 = 7.8 Hz,
J3 = 1.4 Hz, 1 H, arom. CH, 7-H), 8.27 (d, J = 7.8 Hz, 1 H,
arom. CH, 9-H). – 13C NMR (CDCl3): δ = 14.12 (CH3),
22.70 (C-11ꢀ), 26.93 (C-2ꢀ), 29.02 (CH2), 29.04 (CH2),
Discussion
Five new 3-substituted isocoumarins and four new
dihydroisocoumarins were prepared in a convenient
one-pot synthesis, and most of them showed very mod-
erate cytotoxic activities, with the isocoumarins and
the corresponding dihydro derivatives exhibiting al-
most equal potency. The differences in cytotoxic ac-
tivity might be explained on the basis of log P val-
ues. Since none of the compounds prepared here has
cytotoxic activity comparable to the drug candidates
NM-3 and 185322, substitution (hydroxy and methoxy 29.33 (CH2), 29.50 (CH2), 29.51 (CH2), 29.62 (CH2), 29.63
(CH2), 31.93 (CH2), 33.56 (C-1ꢀ), 102.85 (C-4), 120.17
groups) at the benzoid ring of the isocoumarins seems
(C-10), 125.01 (C-6), 127.52 (C-8), 129.53 (C-9), 134.69
(C-7), 137.68 (C-5), 158.40 (C-3), 163.12 (CO). – IR (KBr):
ν = 2924, 2853, 1732, 1657, 1607, 1569, 1484, 1466, 1363,
1326, 1289, 1240, 1204, 1160, 1110, 1046, 1021, 968, 823,
756, 690 cm−1. – MS (EI): m/z (%) = 314 (38) [M]+, 173
(28), 160 (61), 118 (100). – MS (CI): m/z (%) = 315 (100)
[M+1]+.
to be more crucial than the nature of the substituents at
C-3.
Experimental Section
Elemental analysis: Heraeus CHN Rapid; IR spectra:
Perkin-Elmer FT-IR Paragon 1000; MS: Hewlett Packard
MS-Engine, electron ionization (EI) 70 eV, chemical ion-
ization (CI) with CH4 (300 eV); GLC-MS: Shimadzu GC
17 A, EI (70 eV); NMR: Jeol GSX 400 (1H: 400 MHz,
3-(9-Hydroxynonyl)-isochromen-1-one (2b)
The compound was prepared following general procedure
13C: 100 MHz); melting points were determined on a 1 from 2-iodobenzoic acid (496 mg, 2.00 mmol), undec-10-
Unauthenticated
Download Date | 4/7/16 2:38 PM

316
I. Wetzel et al. · New Isocoumarins and Dihydroisocoumarins and their Cytotoxic Activities
yn-1-ol (1.0 g, 6.0 mmol), triethylamine (1.0 g, 10 mmol), 120.10 (C-10), 125.01 (C-6), 127.52 (C-8), 129.49 (C-9),
Pd(PPh3)2Cl2 (70 mg, 0.10 mmol), and ZnCl2 (545 mg, 134.71 (C-7), 137.67 (C-5), 158.56 (C-3), 163.13 (CO). – IR
4.00 mmol) to give 443 mg (77 %) of 2b as a pale-yellow (NaCl, film): ν = 2956, 2928, 2870, 1732, 1657, 1606, 1569,
◦
solid. – M. p.: 63 C. – C18H24O3(288.39): calcd. C 74.97, 1484, 1468, 1367, 1328, 1161, 1108, 1048, 1022, 968, 823,
H 8.39; found C 74.62, H 8.48. – 1H NMR (CDCl3): δ = 757, 691 cm−1. – MS (EI): m/z (%) = 216 (12) [M]+, 160
1.34 (m, 10 H, 5 CH2, 3ꢀ-H – 7ꢀ-H), 1.57 (tt, J1 = J2 = 6.7 Hz, (25), 118 (100). – MS (CI): m/z (%) = 217 (100) [M+1]+.
2 H, CH2, 8ꢀ-H), 1.72 (tt, J1 = J2 = 7.7 Hz, 2 H, CH2, 2ꢀ-H),
2.53 (t, J = 7.7 Hz, 2 H, CH2, 1ꢀ-H), 3.65 (t, J = 6.7 Hz,
( )-3-(2-Hydroxypropyl)-isochromen-1-one (2d)
2 H, CH2, 9ꢀ-H), 6.27 (s, 1 H, arom. CH, 4-H), 7.37 (d, J =
7.8 Hz, 1 H, arom. CH, 6-H), 7.46 (ddd, J1 = J2 = 7.8 Hz,
The compound was prepared following general procedure
1 from 2-iodobenzoic acid (496 mg, 2.00 mmol), pent-4-yn-
J3 = 1.3 Hz, 1 H, arom. CH, 8-H), 7.68 (ddd, J1 = J2
=
2-ol (505 mg, 6.00 mmol), triethylamine (1.0 g, 10 mmol),
Pd(PPh3)2Cl2 (70 mg, 0.10 mmol), and ZnCl2 (545 mg,
4.00 mmol) to give 213 mg (52 %) of 2d as a pale yel-
low oil. – C12H12O3(204.23): calcd. C 70.58, H 5.92; found
C 69.81, H 6.21. – 1H NMR (CDCl3): δ = 1.33 (d, J =
6.3 Hz, 3 H, CH3), 2.64 (dd, J1 = 14.4 Hz, J2 = 8.1 Hz,
1 H, 1ꢀ-H), 2.71 (dd, J1 = 14.4 Hz, J2 = 4.4 Hz, 1 H, 1ꢀ-H),
4.32 (m, 1 H, CH, 2ꢀ-H), 6.39 (s, 1 H, arom. CH, 4-H), 7.39
(d, J = 7.8 Hz, 1 H, arom. CH, 6-H), 7.48 (ddd, J1 = J2 =
7.8 Hz, J3 = 1.4 Hz, 1 H, arom. CH, 8-H), 7.70 (ddd, J1 =
J2 = 7.8 Hz, J3 = 1.4 Hz, 1 H, arom. CH, 7-H), 8.24 (d,
J = 7.8 Hz, 1 H, arom. CH, 9-H). – 13C NMR (CDCl3):
δ = 23.28 (CH3), 43.28 (C-1ꢀ), 65.59 (C-2ꢀ), 105.09 (C-4),
120.25 (C-10), 125.24 (C-6), 127.94 (C-8), 129.55 (C-9),
134.85 (C-7), 137.28 (C-5), 154.96 (C-3), 162.84 (CO). –
IR (NaCl, film): ν = 3429, 2970, 2918, 1718, 1655, 1606,
1483, 1325, 1163, 1119, 1045, 1024, 972, 937, 823, 758,
690 cm−1. – MS (EI): m/z (%) = 204 (16) [M]+, 160 (100),
131 (25). – MS (CI): m/z (%) = 205 (100) [M+1]+. – HR-MS:
m/z = 204.0777 (calcd. 204.0787 for C12H12O3, [M]+).
7.8 Hz, J3 = 1.3 Hz, 1 H, arom. CH, 7-H), 8.26 (d, J =
7.8 Hz, 1 H, arom. CH, 9-H). – 13C NMR (CDCl3): δ =
25.82 (CH2), 27.01 (C-2ꢀ), 29.09 (CH2), 29.33 (CH2), 29.46
(CH2), 29.52 (CH2), 32.88 (C-8ꢀ), 33.67 (C-1ꢀ), 63.04 (C-9ꢀ),
102.90 (C-4), 120.14 (C-10), 125.02 (C-6), 127.55 (C-8),
129.52 (C-9), 134.72 (C-7), 137.66 (C-5), 158.32 (C-3),
163.16 (CO). – IR (KBr): ν = 3437, 2927, 2854, 1730, 1655,
1483, 1277, 1161, 1055, 1022, 756, 692 cm−1. – MS (EI):
m/z (%) = 288 (100) [M]+, 270 (15), 258 (30). – MS (CI):
m/z (%) = 289 (100) [M+1]+. – HR-MS (EI): m/z = 288.1752
(calcd. 288.1726 for C18H24O3, [M]+).
3-(3-Methylbutyl)isochromen-1-one (2c)
a) The compound was prepared following general proce-
dure 1 from 2-iodobenzoic acid (496 mg, 2.00 mmol), 5-
methylhex-1-yne (577 mg, 6.00 mmol), triethylamine (1.0 g,
10 mmol), Pd(PPh3)2Cl2 (70 mg, 0.10 mmol) and ZnCl2
(545 mg, 4.00 mmol) to give 410 mg (95 %) of 2c as a
brown oil.
b) Alternatively the compound was prepared following
general procedure 1 from 2-iodobenzoyl chloride (533 mg,
2.00 mmol), 5-methylhex-1-yne (577 mg, 6.00 mmol),
triethylamine (1.0 g, 10 mmol), Pd(PPh3)2Cl2 (70 mg,
0.10 mmol), and ZnCl2 (545 mg, 4.00 mmol) to give 276 mg
(64 %) of 2c as a brown oil.
2-[4-(1-Oxo-1H-isochromen-3-yl)-butyl]isoindol-1,3-dione
(2e)
The compound was prepared following general procedure
1 from 2-iodobenzoic acid (496 mg, 2.00 mmol), N-(hex-5-
c) 700 mg (3.04 mmol) of 5 was dissolved in 50 mL of a ynyl)-phthalimide (1.36 g, 6.00 mmol), triethylamine (1.0 g,
methanolic KOH solution (5 %) and refluxed for 48 ◦C. The 10 mmol), Pd(PPh3)2Cl2 (70 mg, 0.100 mmol), and ZnCl2
solution was neutralized with hydrochloric acid, diluted with (545 mg, 4.00 mmol) to give 285 mg (41 %) of 2e as a white
water and extracted with diethyl ether (3×40 mL). The com- powder. – M. p.: 168 ◦C. – C21H17NO4 (347.37): calcd.
bined organic layers were dried over Na2SO4, the solvent C 72.61, H 4.93, N 4.03; found C 72.36, H 5.37, N 3.88. –
was evaporated, and the residue was purified by flash col- 1H NMR (CDCl3): δ = 1.78 (m, 4 H, 2 CH2, 2ꢀ-H and 3ꢀ-H),
umn chromatography (ethyl acetate / n-hexane 1 : 1) to give 2.59 (t, J = 6.7 Hz, 2 H, CH2, 4ꢀ-H), 3.74 (t, J = 6.5 Hz,
40 mg (6 %) of 2c as a brown oil. – C14H16O2 (216.28): 2 H, CH2, 1ꢀ-H), 6.27 (s, 1 H, arom. CH, 4ꢀꢀ-H), 7.35 (d, J =
calcd. C 77.75, H 7.46; found C 77.89, H 8.02. – H NMR 8.0 Hz, 1 H, arom. CH, 6ꢀꢀ-H), 7.45 (ddd, J1 = J2 = 8.0 Hz,
1
(CDCl3): δ = 0.95 (dt, J1 = 6.2 Hz, J2 = 1.8 Hz, 6 H, J3 = 0.8 Hz, 1 H, arom. CH, 8ꢀꢀ-H), 7.67 (ddd, J1 = J2
=
2 CH3, 1ꢀꢀ-H and 4ꢀ-H), 1.62 (m, 3 H, 2ꢀ-H and 3ꢀH), 2.54 8.0 Hz, J3 = 0.8 Hz, 1 H, arom. CH, 7ꢀꢀ-H), 7.71 (dd, J1 =
(t, J = 7.2 Hz, 2 H, CH2 1ꢀ-H), 6.26 (s, 1 H, arom. CH, 5.4 Hz, J2 = 3.0 Hz, 2 H, arom. CH, 6-H and 7-H), 7.84 (dd,
4-H), 7.36 (d, J = 7.8 Hz, 1 H, arom. CH, 6-H), 7.44 (dd, J1 = 5.4 Hz, J2 = 3.0 Hz, 2 H, arom. CH, 5-H and 8-H),
J1 = J2 = 7.8 Hz, 1 H, arom. CH, 8-H), 7.69 (dd, J1 = J2 = 8.24 (dd, J1 = 8.0 Hz, J2 = 0.8 Hz, 1 H, arom. CH, 9ꢀꢀ-H). –
7.8 Hz, 1 H, arom. CH, 7-H), 8.27 (d, J = 7.8 Hz, 1 H, 13C NMR (CDCl3): δ = 24.17 (CH2), 27.90 (CH2), 32.99
arom. CH, 9-H). – 13C NMR (CDCl3): δ = 22.35 (C-1ꢀꢀ and (C-4ꢀ), 37.44 (C-1ꢀ), 103.29 (C-4ꢀꢀ), 120.17 (C-10ꢀꢀ), 123.25
C-4ꢀ), 27.59 (C-3ꢀ), 31.52 (C-2ꢀ), 35.87 (C-1ꢀ), 102.74 (C-4), (C-5 and C-8), 125.10 (C-6ꢀꢀ), 127.68 (C-8ꢀꢀ), 129.52 (C-9ꢀꢀ),
Unauthenticated
Download Date | 4/7/16 2:38 PM

I. Wetzel et al. · New Isocoumarins and Dihydroisocoumarins and their Cytotoxic Activities
317
132.07 (C-4 and C-9), 133.96 (C-6 and C-7), 134.73 (C-7ꢀꢀ), 272 (75), 260 (79), 147 (98), 118 (100). – HR-MS (EI): m/z =
137.45 (C-5ꢀꢀ), 157.32 (C-3ꢀꢀ), 162.95 (C-1ꢀꢀ), 168.41 (C-1 290.1894 (calcd. 290.1882 for C18H26O3, [M]+).
and C-3). – IR (KBr): ν = 2927, 2858, 1766, 1709, 1657,
1604, 1566, 1506, 1483, 1466, 1435, 1398, 1371, 1338,
1219, 1203, 1051, 914, 822, 760, 721, 687 cm−1. – MS (EI):
m/z (%) = 347 (74) [M]+, 187 (30), 173 (100), 160 (54). –
MS (CI): m/z (%) = 348 (100) [M+1]+. – HR-MS: m/z =
347.1151 (calcd. 347.1158 for C21H17NO4, [M]+).
( )-3-(3-Methylbutyl)-isochroman-1-one (3c)
The compound was prepared following general procedure
2 from 2c (200 mg, 0.925 mmol) to give 200 mg (99 %) of
3c as a pale-brown oil. – C14H18O2 (218.30): calcd. C 77.03,
H 8.31; found C 77.10, H 8.76. – 1H NMR (CDCl3): δ = 0.93
(d, J = 6.8 Hz, 6 H, 2 CH3), 1.34 (m, 1 H, 2ꢀ-H), 1.50 (m,
1 H, 2ꢀ-H), 1.60 (m, 1 H, CH, 3ꢀ-H), 1.75 (m, 1 H, 1ꢀ-H),
( )-3-Dodecylisochroman-1-one (3a)
The compound was prepared following general procedure 1.88 (m, 1 H, 1ꢀ-H), 2.95 (m, 2 H, CH2, 4-H), 4.50 (m,
2 from 2a (205 mg, 0.652 mmol) to give◦ 110 mg (53 %) 1 H, CH, 3-H), 7.24 (d, J = 7.7 Hz, 1 H, arom. CH, 6-H),
of 3a as a pale-yellow solid. – M. p.: 49 C. – C21H32O2 7.39 (ddd, J1 = J2 = 7.7 Hz, J3 = 1.0 Hz, 1 H, arom. CH,
(316.49): calcd. C 79.70, H 10.19; found C 79.48, H 10.54. – 8-H), 7.53 (ddd, J1 = J2 = 7.7 Hz, J3 = 1.0 Hz, 1 H, arom.
1H NMR (CDCl3): δ = 0.88 (t, J = 7.2 Hz, 3 H, CH3), 1.26 CH, 7-H), 8.09 (dd, J1 = 7.7 Hz, J2 = 1.0 Hz, 1 H, arom.
(m, 18 H, 9 CH2, 3ꢀ-H – 11ꢀ-H), 1.46 (m, 1 H, 2ꢀ-H), 1.57 CH, 9-H). – 13C NMR (CDCl3): δ = 22.47 (2 CH3), 27.91
(m, 1 H, 2ꢀ-H), 1.72 (m, 1 H, 1ꢀ-H), 1.88 (m, 1 H, 1ꢀ-H), (C-3ꢀ), 32.89 (C-1ꢀ), 33.24 (C-4), 33.88 (C-2ꢀ), 77.37 (C-3),
2.94 (m, 2 H, CH2, 4-H), 4.52 (m, 1 H, CH, 3-H), 7.24 152.21 (C-10), 127.35 (C-6), 127.58 (C-8), 130.24 (C-9),
(d, J = 7.8 Hz, 1 H, arom. CH, 6-H), 7.38 (dd, J1 = J2
=
133.65 (C-7), 139.25 (C-5), 165.75 (CO). – IR (NaCl, film):
7.8 Hz, 1 H, arom. CH, 8-H), 7.53 (ddd, J1 = J2 = 7.8 Hz, ν = 2954, 2870, 1726, 1608, 1460, 1385, 1367, 1281, 1252,
J3 = 1.3 Hz, 1 H, arom. CH, 7-H), 8.09 (dd, J1 = 7.8 Hz, 1117, 1086, 1032, 744, 694 cm−1. – MS (EI): m/z (%) = 218
J2 = 1.3 Hz, 1 H, arom. CH, 9-H). – 13C NMR (CDCl3): (15) [M]+, 162 (15), 147 (57), 119 (100), 118 (86). – MS
δ = 14.14 (CH3), 22.70 (CH2), 24.97 (C-2ꢀ), 29.41 (CH2), (CI): m/z (%) = 219 (100) [M+1]+ – HR-MS (EI): m/z =
29.46 (CH2), 29.55 (CH2), 29.62 (2 CH2), 29.70 (CH2), 218.1307 (calcd. 218.1309 for C14H18O2, [M]+).
29.72 (CH2), 31.98 (CH2), 33.27 (C-4), 35.05 (C-1ꢀ), 78.84
(C-3), 125.25 (C-10), 127.34 (C-6), 127.58 (C-8), 130.26
(C-9), 133.62 (C-7), 139.25 (C-5), 165.74 (CO). – IR (KBr):
ν = 2918, 2850, 1714, 1608, 1473, 1462, 1437, 1369, 1288,
1244, 1232, 1119, 1088, 1030, 1001, 741, 694 cm−1. – MS
(EI): m/z (%) = 316 (22) [M]+, 147 (100), 136 (31), 118
(89). – MS (CI): m/z ( %) = 317 (100) [M+1]+.
3-(2-Hydroxypropyl)-isochroman-1-one (3d)
The compound was prepared following general procedure
2 from 2d (55 mg, 0.759 mmol) to give 110 mg (70 %) of
3d (diastereomeric mixture) as a pale-yellow oil. The dia-
stereomers could not be separated by flash column chro-
matography. – 1H NMR (CDCl3): diastereomer 1 (60 %):
δ = 1.29 (d, J = 6.2 Hz, 3 H, CH3, 3ꢀ-H), 1.87 (m, 1 H,
1ꢀ-H), 2.13 (m, 1 H, 1ꢀ-H), 3.00 (m, 2 H, CH2, 4-H), 4.19
( )-3-(9-Hydroxynonyl)-isochroman-1-one (3b)
The compound was prepared following general procedure (m, 1 H, CH, 2ꢀ-H), 4.76 (m, 1 H, CH, 3-H), 7.26 (d, J =
2 from 2b (200 mg, 0.694 mmol) to give 200 mg (99 %) of 3b 7.7 Hz, 1 H, arom. CH, 6-H), 7.41 (dd, J1 = J2 = 7.7 Hz, 1 H,
as a white solid. – M. p.: 63 ◦C. – C18H26O3 (290.41): calcd. arom. CH, 8-H), 7.55 (dd, J1 = J2 = 7.7 Hz, 1 H, arom. CH,
C 74.45, H 9.02; found C 74.69, H 9.18. – 1H NMR (CDCl3): 7-H), 8.10 (d, J = 7.7 Hz, 1 H, arom. CH, 9-H); diastere-
δ = 1.32 (m, 10 H, 5 CH2, 3ꢀ-H – 7ꢀ-H), 1.57 (m, 4 H, 2 CH2, omer 2 (40 %): δ = 1.28 (d, J = 6.2 Hz, 3 H, CH3, 3ꢀ-H),
2ꢀ-H and 8ꢀ-H), 1.72 (m, 1 H, 1ꢀ-H), 1.88 (m, 1 H, 1ꢀ-H), 1.78 (m, 1 H, 1ꢀ-H), 2.00 (m, 1 H, 1ꢀ-H), 3.00 (m, 2 H, CH2,
2.90 (dd, J1 = 16.3 Hz, J2 = 3.5 Hz, 1 H, 4-H), 2.99 (dd, J1 = 4-H), 4.29 (m, 1 H, CH, 2ꢀ-H), 4.85 (m, 1 H, CH, 3-H), 7.26
16.3 Hz, J2 = 11.0 Hz, 1 H, 4-H), 3.65 (t, J = 6.6 Hz, 2 H, (d, J = 7.7 Hz, 1 H, arom. CH, 6-H), 7.41 (dd, J1 = J2
=
CH2, 9ꢀ-H), 4.52 (m, 1 H, CH, 3-H), 7.24 (d, J = 7.6 Hz, 1 H, 7.7 Hz, 1 H, arom. CH, 8-H), 7.55 (dd, J1 = J2 = 7.7 Hz,
arom. CH, 6-H), 7.39 (dd, J1 = J2 = 7.6 Hz, 1 H, arom. CH, 1 H, arom. CH, 7-H), 8.10 (d, J = 7.7 Hz, 1 H, arom. CH,
8-H), 7.53 (ddd, J1 = J2 = 7.6 Hz, J3 = 1.1 Hz, 1 H, arom. 9-H). – 13C NMR (CDCl3): diastereomer 1: δ = 23.75 (CH3),
CH, 7-H), 8.09 (dd, J1 = 7.6 Hz, J2 = 1.1 Hz, 1 H, arom. CH, 33.36 (C-4), 43.73 (C-1ꢀ), 65.43 (C-2ꢀ), 76.01 (C-3), 125.23
9-H). – 13C NMR (CDCl3): δ = 24.87 (C-2ꢀ), 25.70 (CH2), (C-10), 127.40 (C-6), 127.74 (C-8), 130.38 (C-9), 133.84
29.34 (CH2), 29.35 (CH2), 29.38 (CH2), 29.45 (CH2), 32.76 (C-7), 139.20 (C-5), 165.23 (CO); diastereomer 2: δ = 24.26
(C-8ꢀ), 33.39 (C-4), 35.14 (C-1ꢀ), 63.04 (C-9ꢀ), 78.77 (C-3), (CH3), 33.69 (C-4), 44.00 (C-1ꢀ), 63.78 (C-2ꢀ), 77.71 (C-3),
125.23 (C-10), 127.35 (C-6), 127.60 (C-8), 130.26 (C-9), 125.10 (C-10), 127.37 (C-6), 127.67 (C-8), 130.30 (C-9),
133.64 (C-7), 139.23 (C-5), 165.76 (CO). – IR (KBr): ν = 133.78 (C-7), 139.40 (C-5), 165.59 (CO). – IR (NaCl, film):
3431, 2925, 2852, 1716, 1608, 1462, 1290, 1122, 1076, ν = 3418, 2966, 2925, 1719, 1606, 1460, 1375, 1291, 1263,
1030, 741, 694 cm−1. – MS (EI): m/z (%) = 290 (25) [M]+, 1117, 1086, 1031, 914, 848, 800, 746, 695 cm−1. – MS (CI):
Unauthenticated
Download Date | 4/7/16 2:38 PM

318
I. Wetzel et al. · New Isocoumarins and Dihydroisocoumarins and their Cytotoxic Activities
m/z (%) = 207 (100) [M+1]+. – HR-MS (EI): m/z = 206.0932 vent was evaporated and the residue purified by FCC (n-
(calcd. 206.0943 for C12H14O3, [M]+).
hexane / ethyl acetate) to give 1.76 g (97 %) of 5 as a brown
oil. – C15H18O2 (230.31): calcd. C 78.23, H 7.88; found
C 77.91, H 8.42. – 1H NMR (CDCl3): δ = 0.94 (d, J = 7.1 Hz,
6 H, 2 CH3, 1ꢀꢀ-H and 6-H), 1.55 (dt, J1 = J2 = 7.1 Hz,
2 H, CH2, 4ꢀ-H), 1.79 (tsept, J1 = J2 = 7.1 Hz, 1 H, CH,
5ꢀ-H), 2.48 (t, J = 7.1 Hz, 2 H, CH2, 3ꢀ-H), 3.91 (s, 3 H,
CH3, 1ꢀꢀꢀ-H), 7.30 (ddd, J1 = 1.1 Hz, J2 = J3 = 7.8 Hz, 1 H,
arom. CH, 5-H), 7.41 (ddd, J1 = 1.1 Hz, J2 = J3 = 7.8 Hz,
1 H, arom. CH, 4-H), 7.49 (d, J = 7.8 Hz, 1 H, arom. CH,
3-H), 7.87 (d, J = 7.8 Hz, 1 H, arom. CH, 6-H). – 13C NMR
(CDCl3): δ = 17.81 (C-3ꢀ), 22.22 (C-6ꢀ and C-1ꢀꢀ), 27.31
(CH, C-5ꢀ), 37.60 (C-4ꢀ), 52.03 (C-1ꢀꢀꢀ), 79.40 (C-1ꢀ), 96.04
(C-2ꢀ), 124.51 (C-1), 127.11 (C-5), 130.13 (C-6), 131.45
(C-4), 131.98 (C-2), 134.22 (C-3), 167.04 (CO). – IR (NaCl,
film): ν = 2953, 2869, 2360, 2231, 1733, 1716, 1596, 1567,
1484, 1447, 1432. 1293, 1276, 1249, 1128, 1083, 756, 701,
472 cm−1. – MS (EI): m/z (%) = 230 (15) [M]+, 215 (32),
183 (64), 174 (100), 159 (74), 131 (34), 115 (41). – MS (CI):
m/z (%) = 231 (100) [M+1]+.
1,2,3,4-Tetrahydropyrido[1,2-b]isoquinolin-6-one (4)
500 mg (1.44 mmol) of 2e was dissolved in 30 mL of
absolute ethanol, and 2.9 mL (2.9 mmol) of a 1 M hydrazine
solution in THF was added. The mixture was refluxed for
6 h, the suspension was filtered, the filtrate was evaporated,
and the residue was purified by flash column chromatography
(ethyl acetate / n-hexane 3 : 1) to give 90 mg (31 %) of 4 as a
white solid. The spectroscopic data were in full accordance
those described in ref. [19].
Methyl 2-(5-methylhex-1-ynyl)-benzoate (5)
CuI (68 mg, 0.36 mmol) was dissolved in 50 mL of dry tri-
ethylamine, and methyl 2-iodobenzoate (2.06 g, 7.86 mmol),
Pd(PPh3)2Cl2 (80 mg, 0.11 mmol) and 5-methylhex-1-yne
(756 mg, 7.86 mmol) were added. The mixture was stirred
for 24 h under N2 atmosphere. The solvent was evaporated,
the residue dissolved in 50 mL of 5 % aqueous Na2S2O3
solution, extracted with diethyl ether (3 × 50 mL), and the
combined organic layers were dried over Na2SO4. The sol-
Acknowledgement
We thank Martina Stadler for technical support.
[1] R. A. Hill, in Progress in the Chemistry of Organic Nat-
ural Products, Vol. 48, Springer Verlag, Wien, New
York, 1986.
[2] E. Napolitano, Org. Prep. Proced. Int. 1997, 29, 631 –
664.
[12] N. G. Kundu, M. J. Pal, J. Chem. Soc., Chem. Commun.
1993, 86 – 88.
[13] H.-Y. Liao, C.-H. Cheng, J. Org. Chem. 1995, 60,
3711 – 3716.
[14] V. Subramanian, V. R. Batchu, D. Barange, M. Pal,
J. Org. Chem. 2005, 70, 4778 – 4783.
[15] D. Villemin, D. Goussu, Heterocycles 1989, 29, 1255 –
1261.
[16] J. Krauss, D. Unterreitmeier, C. Neudert, F. Bracher,
Arch. Pharm. Pharm. Med. Chem. 2005, 338, 605 –
608.
[3] E. A. Markaryan, Russ. Chem. Rev. 1989, 58, 479 –
493.
[4] Y.-F. Huang, L.-H. Li, L. Tian, H.-M. Hua, Y.-H. Pei,
J. Antibiot. 2006, 59, 355 – 357.
[5] E. M. K. Wijerantne, P. A. Paranagama, A. A. L. Gu-
natilaka, Tetrahedron 2006, 62, 8439 – 8446.
[6] C. L. Reimer, N. Agata, J. G. Tamman, M. Bam-
berger, W. M. Dickerson, G. D. Kamphaus, S. L. Rook,
M. Milhollen, R. Fram, R. Kalluri, D. Kufe, S. Khar-
banda, Cancer Res. 2002, 62, 789 – 795.
[7] T. Kawano, N. Agata, S. Kharbanda, D. Avigan,
D. Kufe, Cancer Chemother. Pharmacol. 2007, 59,
329 – 335.
[17] R. A. Hill, R. H. Carter, J. Staunton, J. Chem. Soc.,
Perkin Trans. 1 1981, 2570 – 2576.
[18] J. Reisch, H. Labitzke, Arch. Pharm. 1975, 308, 713 –
716.
[19] M. Menes-Arzate, M. Martinez, R. Cruz-Almanza,
J. M. Muchowski, Y. M. Osornio, L. D. Miranda,
J. Org. Chem. 2004, 69, 4001 – 4004.
[8] W. Zhang, K. Krohn, S. Draeger, B. Schulz, J. Nat.
Prod. 2008, 71, 1078 – 1081.
[9] M. Azumi, K.-i. Ogawa, T. Fujita, M. Takeshita,
R. Yoshida, T. Furumai, Y. Igarashi, Tetrahedron 2008,
64, 6420 – 6425.
[20] DIN Deutsches Institut fu¨r Normung e. V., Meth-
oden zur Empfindlichkeitspru¨fung von mikrobiellen
Krankheitserregern gegen Chemotherapeutika, DIN
58940, Teil 3 - Beiblatt 1 und Teil 4 - Beiblatt 1, Beuth
Verlag, Berlin 1998.
[10] D. E. Korte, L. S. Hegedus, R. K. Wirth, J. Org. Chem.
1977, 42, 1329 – 1336.
[11] R. C. Larock, S. Varaprath, H. H. Lau, C. A. Fellows,
J. Am. Chem. Soc. 1984, 106, 5274 – 5284.
[21] T. J. Mosmann, Immunol. Methods 1983, 65, 55 – 59.
[22] S. H. Unger, J. R. Cook, J. S. Hollenberger, J. Pharm.
Sci. 1978, 67, 1364 – 1367.
Unauthenticated
Download Date | 4/7/16 2:38 PM