Olefinic isothiocyanates and iminodithiocarbonates from the liverwort Corsinia coriandrina

Article abstract of DOI:10.1002/ejoc.200400586

The chemical investigation of the liverwort Corsinia coriandrina, Corsiniaceae, resulted in the isolation, structure elucidation and synthesis of four sulfur- and nitrogen -containing compounds. The coriandrins were identified as (Z)- and (E)-2-(4-methoxyphenyl)ethenyl isothiocyanates, while the O-methyltridentatols contain the corresponding (Z)- and (E)-S,S-dimethyl 2-(4-methoxyphenyl)ethenyliminodithiocarbonate structures. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.

Full text of DOI:10.1002/ejoc.200400586

FULL PAPER
Olefinic Isothiocyanates and Iminodithiocarbonates from the Liverwort
Corsinia coriandrina
Stephan H. von Reuß*[a] and Wilfried A. König[a][†]
Keywords: Corsinia coriandrina / Liverworts / Natural products / Coriandrin / Tridentatol / Isothiocyanates / Iminodithi-
ocarbonates
The chemical investigation of the liverwort Corsinia coriand-
rina, Corsiniaceae, resulted in the isolation, structure eluci-
dation and synthesis of four sulfur- and nitrogen-containing
compounds. The coriandrins were identified as (Z)- and (E)-
2-(4-methoxyphenyl)ethenyl isothiocyanates, while the O-
methyltridentatols contain the corresponding (Z)- and (E)-
S,S-dimethyl 2-(4-methoxyphenyl)ethenyliminodithiocar-
bonate structures.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
deamination. The only known nitrogen-containing natural
products in liverworts are the 6- and 7-prenylindoles in
some Riccardia species.[6,7] Sulfur-containing metabolites
are equally rare: isotachins with a β-S-methylthio-(E)-acry-
late structure have been obtained from Isotachis japonica
and Balantiopsis rosea.[8,9]
Introduction
Of the numerous natural products that contain both sul-
fur and nitrogen atoms, organic isothiocyanates are one of
the largest and most abundant groups. Hundreds of isothi-
ocyanates with varying carbon skeletons that originate from
amino acid or terpene-derived precursors of higher plants,
fungi, blue-green algae and marine organisms have pre-
viously been reported.[1–3] Within the plant kingdom more
than 120 isothiocyanates formed from amino acid metabo-
lism are known to be prominent among various dicotyle-
donous angiosperms and clustered within the Brassicaceae
(Cruciferae). When plant cells are disrupted in herbivore
attack β-thioglucoside-N-hydroxyiminosulfates (glucosinol-
ates) are converted by a β-thioglucosidase (myrosinase) into
the corresponding isothiocyanates; this process constitutes
a chemical defence mechanism that deters attack by various
herbivores and also antimicrobial activity against a number
of fungal and bacterial plant pathogens.[3]
The fact that mosses (Bryophytes) and, in particular, liv-
erworts (Hepaticae) are rarely attacked by herbivores or mi-
croorganisms has caused much speculation about the spe-
cific constituents responsible for this inertness. It is known
that liverworts accumulate secondary metabolites with a
large variety of structures, mainly terpenoids and aromatic
compounds, within special compartments of the cell.[4,5]
These essential oils are believed to act as a chemical de-
fence. In contrast to higher plants, sulfur- and nitrogen-con-
taining metabolites are virtually unknown in liverworts. Al-
though a number of their constituents apparently originate
from amino acid metabolism, their biogenesis involves early
In previous publications, the liverwort-specific dor-
mancy-inducing factor, lunularic acid, and its decarboxyl-
ation product, lunularin,[10] as well as the flavonols, querce-
tin and kaempferol,[11,12] and some fatty acids[13] were de-
scribed as natural constituents of the liverwort Corsinia co-
riandrina (Corsiniaceae), a relict member of the Marchanti-
ales distributed in Mediterranean areas.[14] We now report
on the isolation, identification and synthesis of the first sul-
fur- and nitrogen-containing metabolites 1–4 of the liver-
wort Corsinia coriandrina (Scheme 1). The coriandrins are
major constituents of the essential oil and were identified
as the (Z)- and (E)-configured 2-(4-methoxyphenyl)ethenyl
isothiocyanates 1 and 2, while the O-methyltridentatols are
minor constituents representing the (Z)- and (E)-configured
S,S-dimethyl 2-(4-methoxyphenyl)ethenyliminodithiocar-
bonate structures 3 and 4.
Results and Discussion
From the thallus cell material of Corsinia coriandrina
(Spreng.) Lind. (Corsiniaceae), collected in Andalusia
(Spain) at an elevation of about 500 m above sea level, the
essential oil was obtained by hydrodistillation or extraction
with diethyl ether and then analysed by GC and GC–MS.
α-Pinene, (E)-β-caryophyllene and (E)-nerolidol were iden-
tified as major constituents of the oil by comparison of the
mass spectra and retention indices with a spectral library
established under identical experimental conditions.[15] In
addition, several known and unknown mono-, sesqui- and
[a] Institut für Organische Chemie, Universität Hamburg,
Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
Fax: +49-40-42838-2893
E-mail: s.von.reuss@web.de
[†] Deceased on November 19, 2004; his scientific achievements
keep him among us.
1184
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
DOI: 10.1002/ejoc.200400586
Eur. J. Org. Chem. 2005, 1184–1188

Olefinic Isothiocyanates and Iminodithiocarbonates from Corsinia coriandrina
FULL PAPER
shift as well as intensive valence vibration bands at ν = 2096
˜
and 2058 cm–1 in its GC–FTIR spectrum, the heterocumu-
lene substituent was identified as an isothiocyanate group,[2]
from which a structure of (Z)-2-(4-methoxyphenyl)ethenyl
isothiocyanate was established for coriandrin (1). Small
amounts of the isomeric (E)-coriandrin (2) were also de-
tected in the diethyl ether extract of C. coriandrina (3.4%
of the total volatile components).
In addition to the coriandrins 1 and 2 minor quantities
of two isomeric sulfur- and nitrogen-containing compounds
(3, 4), with a signal for the molecular ion at m/z = 253 [M]+,
were observed in the diethyl ether extract of C. coriandrina
(1.6 and 1.0% of the total volatile components, respectively)
. After column-chromatographic prefractionation, 3 and 4
were isolated by preparative thin-layer chromatography.
High-resolution mass spectrometry afforded the molecular
formula of C12H15NOS2 with six units of unsaturation. The
high sulfur content of the compounds was also indicated by
a relatively intense signal at [M + 2]+ (9%). The mass spec-
tra of 3 and 4 exhibited some similarities to those of the
coriandrins 1 and 2, suggesting a similar carbon skeleton.
A 2-(4-methoxyphenyl)ethenyl structure was deduced from
the 1H NMR spectrum (Table 1) in agreement with the
long-range coupling correlations in the H,H-COSY spec-
trum. Although predominantly present as the (Z) isomer 3,
the corresponding (E) isomer 4 was also detected. Never-
theless, the heteroatomic substituent of 3 and 4 could not
be identified from the spectroscopic data owing to signals
1
in the H NMR spectrum overlapping with signals from
impurities and because of missing correlations in the H,H-
COSY and H,H-TOCSY spectra. Inspection of the mass
spectrometric fragmentation pattern, in combination with
the HRMS measurements, excluded the presence of a het-
Scheme 1. Coriandrins 1, 2 and O-methyltridentatols 3, 4 from
Corsinia coriandrina.
diterpenoids, unbranched oxygenated aliphatics and fatty erocyclic moiety as the signal at m/z = 206 [M – SCH3]+ is
acids were detected as minor constituents. Dimethyltrisulf- the base peak, which suggests an S-methyl N-methyldithio-
ide and dimethyltetrasulfide,[16,17] as well as S-methyl meth- carbamate or an S,S-dimethyl iminodithiocarbonate sub-
anethiosulfonate,[18,19] previously reported from various stituent. The structures of 3 and 4 were consequently pro-
biological sources, were identified in a liverwort for the first posed to be S,S-dimethyl (Z)- and (E)-2-(4-methoxyphenyl)
time.
ethenyliminodithiocarbonate as 4-methoxyphenylethanal
A new nitrogen-containing compound, which we like to and S,S-dimethyl dithiocarbonate were observed as cleav-
call coriandrin (1), with a signal for the molecular ion at age products of the labile enamine intermediate formed
m/z = 191 [M]+, was observed as a major constituent of the upon hydrolysis of the compounds. The free phenols and
diethyl ether extract (20.4% of the total volatiles). After O-sulfates corresponding to 3 and 4 have previously been
flash chromatographic prefractionation, coriandrin (1) was described from the marine hydroid, Tridentata marginata,
isolated by repeated column chromatography. It was estab- Sertulariidae, and were called tridentatols.[20,21]
lished by high-resolution mass spectrometry that coriandrin
The structures of the coriandrins 1, 2 and O-methyltri-
1 has the molecular formula of C10H9NOS with seven units dentatols 3, 4 were finally confirmed by their synthesis
of unsaturation. One para-disubstituted benzene unit, one (Scheme 2). While a synthetic access to (E)-O-methyltri-
methoxy group and a (Z)-configured ethenyl residue were dentatol A (4) has already been described[22] we have estab-
1
observed in its H NMR spectrum (Table 1), in agreement lished a different pathway to (Z)- and (E)-O-methyltri-
with carbon signals for one methyl group, six methine dentatol (3 and 4), which also provided (Z)- and (E)-corian-
groups and three quaternary carbons in its 13C PENDANT drin (1 and 2) as synthetic intermediates. 2-Hydroxy-2-(4-
spectrum (Table 2). By inspection of the H,H-COSY, methoxyphenyl)ethylammonium chloride (5) was prepared
HMQC and HMBC spectra a (Z)-2-(4-methoxyphenyl)eth- in 70% yield over two steps from 2-bromo-1-(4-meth-
enyl skeleton was identified which accounts for five of the oxyphenyl)ethanone. Treatment of 5 with thionyl chloride
seven units of unsaturation. The remaining quaternary car- afforded the 2-chloro derivative 6 in 80% yield.[23] Standard
bon was only observed by H,C-correlation signals in its thiophosgenation procedures failed owing to hydrolysis of
HMBC spectrum at δC = 135.6 ppm. From its chemical the benzylic chlorine followed by cyclisation to oxazolidine-
Eur. J. Org. Chem. 2005, 1184–1188
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1185

S. H. von Reuß, W. A. König
FULL PAPER
1
Table 1. H NMR spectroscopic data for coriandrins 1, 2 and O-methyltridentatols 3, 4.[a]
H atom
(Z)-1
(E)-2
(Z)-3
(E)-4
SCH3
SCH3
1
–
–
–
–
2.15, 6 H, br. s
2.11, 3 H, br. s
2.27, 3 H, br. s
7.93, 1 H, d, 13.2
6.96, 1 H, d, 13.2
7.28, 2 H, d, 8.5
6.70, 2 H, d, 8.8
3.27, 3 H, s
5.18, 1 H, d, 8.2
5.45, 1 H, d, 8.2
7.37, 2 H, d, 8.8
6.60, 2 H, d, 8.8
3.20, 3 H, s
5.52, 1 H, d, 13.7
5.98, 1 H, d, 13.7
6.74, 2 H, d, 8.7
6.60, 2 H, d, 8.9
3.22, 3 H, s
7.16, 1 H, d, 8.5
5.98, 1 H, d, 8.5
7.86, 2 H, d, 8.8
6.84, 2 H, d, 8.8
3.31, 3 H, s
2
2Ј,6Ј
3Ј,5Ј
4Ј-OCH3
[a] Measured in [D6]C6H6 (500 MHz); δH in ppm, integral, multiplicity, J in Hz; assignments made by COSY experiments.
Table 2. 13C NMR spectroscopic data for coriandrins 1, 2 and O- mixture of the S,S-dimethyl 2-(4-methoxyphenyl)ethenyl-
methyltridentatols 3, 4.[a]
iminodithiocarbonates 3 and 4, which were separated by
preparative gas chromatography using a column packed
witha cyclodextrin derivative.[24] The MS, IR and NMR
spectroscopic data of natural and synthetic (Z)- and (E)-
coriandrin as well as (Z)- and (E)-O-methyltridentatol are
completely identical. While (E)-O-methyltridentatol A (4)
C atom
(Z)-1
(E)-2
(Z)-3
(E)-4
SCH3
N=C
1
2
1Ј
2Ј,6Ј
3Ј,5Ј
4Ј
Ϫ
Ϫ
15.1, q
162.0, s
131.4, d
121.9, d
130.5, s
132.0, d
114.2, d
159.3, s
55.0, q
15.1, q
159.6, s
132.9, d
127.8, d
130.2, s
128.1, d
114.8, d
159.8, s
55.0, q
135.6, s
111.3, d
127.8, d
126.9, s
130.6, d
114.6, d
160.7, s
55.0, q
134.2, s
113.5, d
131.2, d
130.6, s
128.1, d
114.7, d
160.9, s
55.0, q
1
exhibits two H NMR signals for the methylthio groups in
different solvents, (Z)-O-methyltridentatol B (3) displays
only one signal (Table 1) as a result of syn–anti topomeris-
ation, which has also been reported for other S,S-dimethyl
iminodithiocarbonates.[21,25]
4Ј-OCH3
[a] Measured in [D6]C6H6 (100 MHz); δC in ppm, multiplicity; as-
signments made by PENDANT, HMQC and HMBC experiments.
The coriandrins 1, 2 and O-methyltridentatols 3, 4 are
the first examples of these classes of compounds to be iden-
tified among the liverworts. Their presence as natural con-
stituents of Corsinia coriandrina has been confirmed by the
independent detection of these compounds by Asakawa in
samples collected in France and Turkey.[26] The coriandrins
1,2 are rare examples of olefinic isothiocyanate compounds,
like axisothiocyanate-4 from the marine sponge Axinella
cannabina.[27] The unusual S,S-dimethyl iminodithiocar-
bonate substructure of the tridentatols has so far only been
encountered among the cruciferous phytoalexins methoxy-
brassenin A and B[25] as well as wasalexin A and B.[28]
Furthermore, the observed co-occurrence of the structurally
related isothiocyanates 1 and 2 and the S,S-dimethyl imino-
dithiocarbonate compounds 3 and 4 in the liverwort Corsi-
nia coriandrina is similar to the presence of glucosinolate-
derived isothiocyanates and the above-mentioned phyto-
alexins in some Cruciferae species.[3,25,28,29]
2-thiones and, consequently, a less nucleophilic solvent sys-
tem had to be explored. After liberation of the free base
with the sterically hindered Hünig base in diethyl ether,
condensation with thiocarbonyl dichloride under basic con-
ditions furnished 2-chloro-2-(4-methoxyphenyl)ethyl isothi-
ocyanate (7) in moderate yield. Through gas-phase dehy-
drochlorination a mixture of the (Z)- and (E)-2-(4-meth-
oxyphenyl)ethenyl isothiocyanates 1 and 2 was obtained in
almost quantitative yield. The geometrical isomers were
separated by preparative gas chromatography. Nucleophilic
addition of (sodium 18-crown-6) methanethiolate complex
to a mixture of 1 and 2 or pure (Z)-configured 1 and meth-
ylation of the resulting intermediates afforded a (Z)/(E)
Scheme 2. Synthetic pathway to coriandrins 1, 2 and O-methyltridentatols 3, 4.
1186 www.eurjoc.org
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Olefinic Isothiocyanates and Iminodithiocarbonates from Corsinia coriandrina
FULL PAPER
1177, 1042, 832 cm–1. EIMS (70 eV): m/z (%) = 191 (100) [M]+, 176
(54), 161 (6), 148 (14), 132 (4), 121 (25), 116 (6), 104 (14), 96 (4),
89 (16), 77 (10), 63 (13), 51 (8), 45 (5). HR-EIMS: m/z = 191.0405
[M]+; calcd. for C10H9NOS: 191.0405; ∆ = 0.0 ppm.
Experimental Section
General Experimental Procedures: Gas chromatograms were re-
corded with a HRGC 5300 Mega instrument (Carlo Erba)
equipped with 25 m fused-silica capillary columns containing pol-
ysiloxanes CPSil-5 and CPSil-19 (Chrompack). Hydrogen at an in-
let pressure of 0.5 bar was used as the carrier gas with a split injec-
tion at 200 °C (split ratio: 1:30) and a flame ionisation detector at
250 °C; temperature program: 50–250 °C at 3 °C/min. GC–EIMS
and GC–HREIMS were measured with a HP 5890 gas chromato-
graph (Hewlett Packard) equipped with a 25 m CPSil-5 CB fused-
silica capillary column (Chrompack) coupled to a VG Analytical
70–250S mass spectrometer; temperature program: 80–270 °C at
10 °C/min. GC–FTIR spectra were recorded with a HP 5890 gas
chromatograph (Hewlett Packard) equipped with a 30 m Innowax
fused-silica capillary column and coupled to a HP 5965 A infrared
spectrometer (Hewlett Packard); temperature program: 80–270 °C
at 10 °C/min. NMR spectra were recorded with an AMX 400 spec-
trometer (Bruker) for 1H NMR (400.1 MHz), broadband-decou-
pled 13C NMR and 13C PENDANT (Polarisation Enhancement
that is Nurtured During Attached Nucleus Testing) spectra
(E)-Coriandrin [(E)-2-(4-Methoxyphenyl)ethenyl Isothiocyanate] (2):
Pale yellow oil. For 1H and 13C NMR ([D6]benzene) data, see
Table 1 and Table 2, respectively. GC–FTIR: ν = 2096 (s, NCS),
˜
2055 (s, NCS), 1610 (C=C), 1513 (C=C), 1251 (COC), 1176,
1042 cm–1. EIMS (70 eV): m/z (%) = 191 (100) [M]+, 176 (58), 161
(6), 148 (16), 132 (5), 121 (30), 116 (7), 104 (19), 96 (7), 89 (24), 77
(17), 63 (44), 51 (17), 45 (13). HR-EIMS: m/z = 191.0410 [M]+;
calcd. for C10H9NOS: 191.0405; ∆ = 2.6 ppm.
Isolation of the O-Methyltridentatols 3 and 4: The crude diethyl
ether extract was purified by chromatography on silica gel 60
(Merck) with an n-hexane/diethyl ether gradient. Preparative thin-
layer chromatography with an eluent of n-hexane/ethyl acetate
(10:1) afforded approximately 0.3 mg (Z)-O-methyltridentatol B (3)
with about 20% of (E)-O-methyltridentatol A (4).
(Z)-O-Methyltridentatol B [S,S-Dimethyl (Z)-2-(4-Methoxyphenyl)
ethenyliminodithiocarbonate] (3): Pale yellow oil. For 1H and 13C
NMR ([D6]benzene) data, see Table 1 and Table 2, respectively.
EIMS (70 eV): m/z (%) = 253 (87) [M]+, 238 (1), 206 (100), 191
(49), 176 (21), 158 (45), 148 (3), 133 (36), 118 (8), 103 (10), 96 (14),
89 (19), 77 (13), 63 (12), 51 (7), 45 (10), 39 (7). HR-EIMS: m/z =
253.0624 [M]+; calcd. for C12H15NOS2: 253.0595; ∆ = 11.5 ppm;
m/z = 206.0642 [M – SCH3]+; calcd. for C11H12NOS: 206.0640;
∆ = 1.0 ppm.
1
(100.6 MHz) and with an AMX 500 spectrometer (Bruker) for H
NMR, H,H-COSY, H,H-TOCSY, HMQC and HMBC spectra (1H:
500.1 MHz; 13C: 125.8 MHz). Homonuclear 1H connectivities were
determined by performing COSY and TOCSY experiments. One-
bond heteronuclear 1H–13C connectivities were determined by
1
using a HSQC pulse sequence [interpulse delay set for J(C,H) =
145 Hz]. Two- and three-bond 1H–13C connectivities were deter-
mined by gradient-selected HMBC experiments optimized for 2,3J
= 7.7 Hz. Preparative GC was carried out with a modified Varian
1400 instrument equipped with stainless steel columns
(1.85 m×4.3 mm) packed with 10% polydimethylsiloxane SE-30 on
Chromosorb W-HP or 6% heptakis(6-O-tert-butyldimethylsilyl-
2,3-di-O-methyl)-β-cyclodextrin in SE-52 (50%, w/w) on Chro-
mosorb W-HP. Helium was used as the carrier gas at a flow rate
of 120 mL/min with a flame ionisation detector at 250 °C and an
injector temperature of 210 °C. Eluting compounds were trapped
in Teflon tubes cooled with liquid nitrogen.[24]
(E)-O-Methyltridentatol A [S,S-Dimethyl (E)-2-(4-Methoxyphenyl)
ethenyliminodithiocarbonate] (4): Pale yellow oil. For 1H and 13C
NMR ([D6]benzene) data, see Table 1 and Table 2, respectively.
EIMS (70 eV): m/z (%) = 253 (85) [M]+, 238 (1), 206 (100), 191
(49), 176 (22), 158 (36), 148 (3), 133 (43), 118 (9), 103 (11), 96 (13),
89 (20), 77 (13), 63 (12), 51 (7), 45 (10), 39 (7). HR-EIMS: m/z =
253.0621 [M]+; calcd. for C12H15NOS2: 253.0595; ∆ = 10.3 ppm;
m/z = 206.0642 [M – SCH3] +; calcd. for C11H12NOS: 206.0640;
∆ = 1.0 ppm.
Plant Material: Corsinia coriandrina (Spreng.) Lind. was collected
at an elevation of approximately 500 m near Tarifa, Andalusia
(Spain), in March 2003 (about 30 g fresh weight) and at 350 m near
St.Bartolomeo, Andalusia, in April 2004 (about 40 g fresh weight).
The liverwort was identified by Professor R. Mues (Universität des
Saarlandes, Germany) and Dr. H. Muhle (University of Ulm, Ger-
many).
Synthesis of 2-Chloro-2-(4-methoxyphenyl)ethylammonium Chloride
(6): A suspension of 2-hydroxy-2-(4-methoxyphenyl)ethylammo-
nium chloride (5) (620 mg, 3.0 mmol) in chloroform (5 mL) at 0 °C
was treated with a solution of thionyl chloride (820 mg, 6.9 mmol)
and dimethylformamide (100 µL) in chloroform (2 mL). After 14 h
solvent and excess reagent were evaporated in vacuo at 20 °C and
the residue was treated with cold ethanol (3 mL). The product was
filtered, washed with cold ethanol (3×1 mL) and diethyl ether
(2 mL) and dried in vacuo to give 6 (540 mg, 2.4 mmol, 80% yield).
Hydrodistillation and Extraction: Carefully cleaned fresh plant ma-
terial of Corsinia coriandrina (30 g) was homogenized in water with
a blender and hydrodistilled for 2 h to give the essential oil, which
was collected in n-hexane. The remaining aqueous homogenate was
extracted with diethyl ether and the organic phase was separated,
dried with Na2SO4 and concentrated in vacuo. Air-dried plant ma-
terial (10 g) was crushed under liquid nitrogen and extracted with
diethyl ether.
1
White solid. H NMR ([D6]DMSO): δ = 2.71 (m, 1 H, 1-H), 2.83
(m, 1 H, 1-HЈ), 3.80 (s, 3 H, 4Ј-OCH3), 5.31 (dd, 1 H, J = 9.6,
4.7 Hz, 2-H), 6.85 (d, 2 H, J = 8.7 Hz, 3Ј,5Ј-H), 7.32 ppm (d, 2 H,
J = 8.9 Hz, 2Ј,6Ј-H). 13C NMR ([D6]DMSO): δ = 45.6 (t, 1-C),
55.6 (q, 4Ј-OCH3), 59.9 (d, 2-C), 114.6 (d, 3Ј,5Ј-C), 127.3 (d, 2Ј,6Ј-
C), 129.9 (s, 1Ј-C), 160.2 ppm (s, 4Ј-C). EIMS (70 eV): m/z (%) =
185 (40) [M – HCl]+, 156 (91), 155 (100), 150 (51), 134 (47), 121
(49), 91 (33), 77 (32), 65 (12), 44 (14), 36 (51).
Isolation of the Coriandrins 1 and 2: The crude essential oil was
purified by chromatography on silica gel 60 (Merck) with an n-
hexane/diethyl ether gradient. Repeated column chromatography
with an n-hexane/dichloromethane gradient gave approximately
2 mg (Z)-coriandrin (1) with about 5% of (E)-coriandrin (2).
Synthesis of 2-Chloro-2-(4-methoxyphenyl)ethyl Isothiocyanate (7):
A
suspension of 2-chloro-2-(4-methoxyphenyl)ethylammonium
chloride (6) (444 mg, 2.0 mmol) in diethyl ether (8 mL) at 0 °C was
treated with N-ethyldiisopropylamine (1 mL, 5.8 mmol). After stir-
(Z)-Coriandrin [(Z)-2-(4-Methoxyphenyl)ethenyl Isothiocyanate] (1): ring for 1 h the resulting suspension was filtered and the solution
Pale yellow oil. For 1H and 13C NMR ([D6]benzene) data, see
added dropwise to a solution of thiocarbonyl dichloride (400 µL,
4.0 mmol) in diethyl ether (8 mL) at 0 °C. After 30 min ice (8 g)
was added and then the organic layer was separated and dried with
Table 1 and Table 2, respectively. GC–FTIR: ν = 2200, 2096 (s,
˜
NCS), 2058 (s, NCS), 1609 (C=C), 1512 (C=C), 1398, 1260 (COC),
Eur. J. Org. Chem. 2005, 1184–1188
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© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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S. H. von Reuß, W. A. König
FULL PAPER
Na2SO4. The product was purified by chromatography on silica
with an n-hexane/diethyl ether mixture (8:1) as eluent to give 7
(164 mg, 720 µmol, 36% yield) as colorless crystals. 1H NMR
([D6]benzene): δ = 2.96 (dd, 1 H, J = 14.5, 6.4 Hz, 1-H), 3.07 (dd,
1 H, J = 14.7, 7.1 Hz, 1-HЈ), 3.20 (s, 3 H, 4Ј-OCH3), 4.26 (t, 1 H,
J = 6.7 Hz, 2-H), 6.61 (d, 2 H, J = 8.7 Hz, 3Ј,5Ј-H), 6.86 ppm (d,
2 H, J = 8.7 Hz, 2Ј,6Ј-H). 13C NMR ([D6]benzene): δ = 52.1 (t, 1-
C), 55.1 (q, 4Ј-OCH3), 60.5 (d, 2-C), 114.7 (d, 3Ј,5Ј-C), 129.0 (d,
2Ј,6Ј-C), 129.8 (s, 1Ј-C), 135.3 (s, NCS), 160.9 ppm (s, 4Ј-C). EIMS
(70 eV): m/z (%) = 227 (8) [M]+, 191 (63), 176 (36), 157 (56), 155
(100), 148 (9), 134 (45), 121 (20), 119 (22), 104 (12), 91 (40), 77
(23), 65 (25), 63 (26), 51 (22), 45 (8), 39 (21). HR-EIMS: m/z =
227.0170 [M]+; calcd. for C10H10NOS35Cl: 227.0172; ∆ = 0.9 ppm.
are grateful to Professor Y. Asakawa (Tokushima Bunri University,
Japan) for providing GC-EIMS data for Corsinia coriandrina.
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µmol) in diethyl ether (2.0 mL) was dehydrochlorinated in 100 µL
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Acknowledgments
We would like to thank Dr. V. Sinnwell (University of Hamburg),
Mr. S. Possner (University of Hamburg), Mrs. A. Meiners and Mr.
M. Preusse (University of Hamburg) for NMR, GC-FTIR, GC-
EIMS and GC-HREIMS measurements, respectively, and also Pro-
fessor R. Mues, (Universität des Saarlandes) and Dr. H. Muhle
(University of Ulm) for the identification of the plant material. We
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Received: August 8, 2004
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Eur. J. Org. Chem. 2005, 1184–1188