Reaction of (+)-carvone with several hetarylsulfenyl chlorides and pyridylselenyl chloride

Article abstract of DOI:10.1007/s10600-014-0930-z

New menthane-type derivatives were prepared via hetarylsulfenyl- chlorination reactions of (+)-carvone with 2-benzothiazolyl-, 4,6-dimethyl-2-pyrimidyl-, and 3-methoxycarbonyl-2-pyridylsulfenyl chlorides and 2-pyridylselenyl chloride.

Full text of DOI:10.1007/s10600-014-0930-z

Chemistry of Natural Compounds, Vol. 50, No. 2, May, 2014 [Russian original No. 2, March–April, 2014]
REACTION OF (+)-CARVONE WITH SEVERAL HETARYLSULFENYL
CHLORIDES AND PYRIDYLSELENYL CHLORIDE
1
1
1*
2
I. V. Kuznetsov, V. A. Startseva, L. E. Nikitina, V. K. Osmanov,
2
2
3
A. V. Borisov, Zh. V. Matsulevich, and V. V. Klochkov
New menthane-type derivatives were prepared via hetarylsulfenyl-chlorination reactions of (+)-carvone
with 2-benzothiazolyl-, 4,6-dimethyl-2-pyrimidyl-, and 3-methoxycarbonyl-2-pyridylsulfenyl chlorides and
2-pyridylselenyl chloride.
Keywords: (+)-carvone, hetarylsulfenyl-chlorination, monoterpenes.
One method for introducing sulfides into unsaturated compounds is to react olefins with sulfenyl chlorides, which
forms primarily the 1,2-trans-addition products, ꢀ-halosulfides.
Reactions of olefins of various structures with hetarylsulfenyl and selenyl chlorides derived from pyridine, pyrimidine,
and benzothiazole were reported [1–4]. The reactions of monoterpenes with heterocyclic sulfenyl chlorides are little studied
with the exception of anecdotal studies on the sulfenyl-chlorination of 3-carene [5], ꢀ-pinene, and limonene [6]. The presence
of three reactive centers in carvone provided an entry for reacting this terpene with various S-containing reagents. Electrophilic
addition of thiols to carvone [7–12] and its sulfenyl-chlorination [13] were described before. However, its reactions with
sulfenyl chlorides containing heterocyclic groups and selenyl-chlorination of monoterpenes have not been reported.
Herein we present results from a study of the functionalization of (+)-carvone (1) using sulfenyl chlorides comprising
promising N-containing pharmacophores (3-methoxycarbonyl-2-pyridyl-, 2-benzothiazolyl-, and 4,6-dimethyl-2-
pyrimidylsulfenyl chlorides) and the reaction of this monoterpene with 2-pyridylselenyl chloride. Sulfenyl chlorides and
selenyl chloride were prepared by the published methods [14–16]. The structures of products isolated by column chromatography
13
1
13
over silica gel were established using PMR, C NMR, and H– C HETCOR spectroscopy and GC-MS.
The endo-cyclic double bond of 1 was conjugated to a carbonyl, which diminished significantly its ability to react
with electrophiles. Therefore, exclusively the exo-cyclic double bond of 1 underwent sulfenyl(selenyl)-chlorination, in contrast
with limonene [6].
7
1
O
O
3
+
5
RSCl
a
8
SR
Cl
10
9
Cl
SR
2 - 4
5
O
CO CH
2
3
R =
N
O
N
S
a
N
N
1
2
3
4, 5
Se
Cl
Se
N
Cl
N
6
a. CH Cl , 25ꢂC
2
2
1) Kazan State Medical University, 420012, Kazanꢁ, Ul. Butlerova, 49, e-mail: valestar@mail.ru; 2) R. E. Alekseev
Nizhnii Novgorod State Technical University, 603950, Nizhnii Novgorod, Ul. Minina, 24, e-mail: tantal@bmail.ru; 3) Kazan
(Privolga) Federal University, 420008, Kazanꢁ, Ul. Kremlevskaya, 18, e-mail: vladimir.klochkov@kpfu.ru. Translated from
Khimiya Prirodnykh Soedinenii, No. 2, March–April, 2014, pp. 244–247. Original article submitted October 25, 2013.
©
276
0009-3130/14/5002-0276 2014 Springer Science+Business Media New York

The reaction of 1 with 3-methoxycarbonyl-2-pyridylsulfenyl chloride was carried out at room temperature in CH Cl
2
2
with an equimolar ratio of reagents and without a catalyst. It formed the single product 2 even if an excess of sulfenyl chloride
was used.
The PMR spectrum of 2 contained a broad singlet for the proton of the endo-cyclic double bond (6.73 ppm), a singlet
for the OCH protons (3.95 ppm), and resonances for protons of the pyridine ring (7.09, 8.21, 8.52 ppm) and terpene backbone
3
(1.79–2.90 ppm). A feature of the PMR spectrum of 2 was the presence of a resonance for the C-8 methyl protons as two
closely spaced singlets with the same intensity (1.61 and 1.62 ppm) in addition to a resonance for the thiomethylene group as
two AB-systems with the same intensity and SSCC (3.70 ppm, 3.80, AB-system; 3.93, 4.03, AꢁBꢁ-system; J = 16.0 Hz). The
doubling of the number of C-8 methyl and thiomethylene lines was explained by the existence of 2 as a mixture of four
stereoisomers with two diastereomers with 8R- and 8S-configurations in an ~1:1 ratio that were responsible for the observed
pattern in the PMR spectrum and their two enantiomers with the 5S,8S- and 5S,8R-configurations. We observed previously a
similar phenomenon for the reaction products of limonene 8,9-oxide with thiols and isothiuronium salts [17].
1
13
The proposed structure of 2 was confirmed by analyzing the two-dimensional H– C HETCOR NMR experiment.
The HETCOR spectrum had cross-peaks for the terpene at 1.80/15.0, corresponding to the 7-methyl; 2.17/27.6, 2.45/39.7, and
2.9/40.2, belonging to bound C–H atoms in the 4- and 6-positions; and 6.73/118.8, belonging to bound C–H atoms of the
endo-cyclic double bond. The spectrum also showed cross-peaks for the pyridine at 7.09/139.2, 8.21/144.3, and 8.52/151.7.
Resonances for bound C–H atoms at the asymmetric center (C-8) were doubled. Two cross-peaks at 1.61/27.1 and 1.62/27.1
corresponded to methyls of two diastereomers. Cross-peaks at 3.75/40.4 and 3.98/40.4 were due to correlation of bound C–H
atoms in the 9-position.
13
The C NMR spectrum also confirmed that 2 existed as a mixture of two pairs of enantiomers with different
arrangements of the C-8 substituents. The spectrum showed a doubled set of C resonances. The C-8 resonance was located at
75.2 and 75.3 ppm, which indicated that it had a Cl atom, whereas C-9 (40.8 and 40.9 ppm) was bonded to a S atom.
+
The mass spectrum of 2 gave a peak with m/z 317 [M – Cl] and fragments characteristic of the menthane system
(m/z 121, 91, 79, 53).
(+)-Carvone was also reacted with this sulfenyl chloride using LiClO :nitromethane in order to produce possibly the
4
cyclization product because it is known that LiClO stimulates polar cycloaddition of hetarylsulfenyl chlorides to multiple
4
bonds [4, 11]. The cyclization product was observed in the analogous reaction with (–)-pinene [6]. However, the reaction with
1 under these conditions formed only 2.
The reaction of 1 with 2-benzothiazolylsulfenyl chloride under the same conditions (CH Cl , terpene:sulfenyl chloride,
2
2
13
1
13
1:1) also formed the single product 3 according to PMR, C NMR, and H– C HETCOR spectroscopy.
Also, the reaction of 1 with 4,6-dimethyl-2-pyrimidinylsulfenyl chloride formed the two regioisomers 4 and 5 that
were characterized as an ~6:1 mixture.
The PMR spectrum of predominant regioisomer 4 contained a singlet for the endo-cyclic double bond proton
(6.72 ppm), two AB-systems of thiomethylene protons from two pairs of enantiomers (3.68, 3.89, AB-system; 3.79, 4.01,
AꢁBꢁ-system; J = 12.0 Hz), and singlets for terpene backbone methyl protons (1.67 and 1.78). The PMR spectrum of minor
isomer 5 showed a singlet for the endo-cyclic double bond proton (6.95 ppm), a quartet for the –CH –Cl protons (4.38,
2
J = 6.4 Hz), a singlet for the endo-cyclic double bond methyl protons (1.60), and a quartet for the C-8 CH protons (1.75,
3
J = 6.4 Hz). Spectra of 4 and 5 also had resonances for the thiazole protons as four multiplets (7.30, 7.42, 7.73, and 7.87 ppm)
and for the other protons of the terpene backbone. The intensities of the C-8 methyl and methylene proton resonances were
doubled because these compounds were mixtures of two pairs of enantiomers in an ~1:1 ratio. This was also confirmed by the
13
C NMR spectrum, in which resonances of each C atom consisted of two lines with similar chemical shifts.
Resonances for the –CH –S– and –CH –Cl groups of regioisomers 4 and 5 were assigned using data from the
2
2
1
13
13
2D H– C NMR HETCOR experiment and the C NMR spectrum. The region for correlation of bound C–H atoms in the
1
13
9-position of 4 and 5 had two cross-peaks in the H– C HETCOR NMR spectrum at 3.78/41.0 and 3.91/41.0 for methylenes
on the S atom of the two stereoisomers of main product 4. Cross-peaks at 4.39/63.9 and 4.41/63.9 were assigned to methylenes
13
on the Cl atom from the two stereoisomers of minor product 5. The C-8 resonance in the C NMR spectrum of main product
4 was located at 74.2 ppm; in the spectrum of minor isomer 5, at 57.8 ppm. This indicated that this C atom was bonded to Cl
in the predominant isomer.
The reaction of 1 with 2-pyridinylselenyl chloride formed a single addition product (6) at the exo-cyclic double bond
according to the expanded Markovnikov rule.
277

The PMR spectrum of 6 had a singlet for the endo-cyclic double bond proton (6.71 ppm), a multiplet for the –CH Se–
2
group (3.87), singlets for protons of the two terpene backbone methyls (1.64 and 1.75), and multiplets for four pyridine
13
protons (7.05, 7.32, 7.44, 8.44 ppm). The C NMR spectrum showed a resonance at 75.5 ppm for the quaternary C-8 atom
13
bound to Cl. Compound 6 existed as a mixture of the 8R- and 8S-stereomers according to PMR and C NMR spectroscopy.
Thus, sulfenyl(selenyl) chlorides added in all studied reactions to the exo-cyclic double bond of 1 primarily according
to the expanded Markovnikov rule.
Our previously published test results for the antifungal activity of a series of S-containing terpenoid derivatives of the
carane-, pinane-, and menthane-types showed that individual menthane-type thioterpenes exhibited high antifungal activity
[18–22].
The antifungal activity of the thioterpenoids with hetarylsulfide groups was studied using a disk-diffusion method on
agar medium [23]. Unfortunately, all compounds possessed low levels of antifungal activity against both mold and mycelial
fungi.
EXPERIMENTAL
The course of reactions and purity of products were monitored by TLC on Silufol UV-254 and Sorbfil plates
(EtOH–H SO –anisaldehyde detector, 90:5:5). Preparative chromatography was performed over KSKG silica gel
2
4
(0.10–0.16 ꢃm, Ekofarm). We used D-(+)-carvone (Acros Organics). Solvents were purified and dried by the usual methods [24].
13
PMR and C NMR spectra were recorded with HMDS internal standard on Bruker Avance 400 (operating frequency
1
13
1
400 and 100 MHz for H and C) and Varian Unity-300 (operating frequency300 MHz for H) spectrometers. Chemical
shifts were determined relative to resonances of residual protons in the deuterated solvent.
GC-MS was carried out on a DFS Thermo Electron Corp. (USA) instrument using electron-impact ionization, ionizing-
electron energy 70 eV; ion-source temperature 280°C, DB-5MS Agilent capillary column (30 m ꢄ 0.254 mm), and He carrier
gas flowing at 1 mL/min. Mass spectra were processed using the Xcalibur program. Samples were diluted in chromatographically
–6
pure C H to a concentration of ~10 mol/ꢃL before injection into the instrument. The sample volume was 1 ꢃL.
6
6
General Method for Synthesizing Sulfenyl Chlorides from Disulfides. Disulfide (1 mmol) in CH Cl (5 mL) was
2
2
treated with a solution of sulfuryl chloride (1 mmol) in CH Cl (5 mL) at 25–30°C and stirred for 2–5 min. The solvent was
2
2
evaporated to afford sulfenyl chlorides that were used in the reactions with the terpenes.
Reaction of 1 with Sulfenyl Chlorides. Freshly prepared sulfenyl chloride (2 mmol) in CH Cl (4 mL) at room
2
2
temperature was stirred, treated with 1 (2 mmol) dissolved in CH Cl (4 mL) (1:1 ratio of reagents), and stirred in a flask on
2
2
a magnetic stirrer. The course of the reaction was monitored by TLC. When the reaction was finished (5–7 d), the solvent was
evaporated (water aspirator). The reaction products were isolated by column chromatography over silica gel (n-hexane–CH Cl )
2
2
as yellowish oils. Yield of 2, 65%; 3, 60%; 4 and 5, 55%.
1
Methyl 2-{[2-Chloro-2-(4-methyl-5-oxocyclohex-3-en-1-yl)propyl]thio}pyridine-3-carboxylate (2). H NMR
spectrum (300 MHz, ÑDCl , ꢅ, ppm, J/Hz): 1.61 and 1.62 (3Í, s, Í-10), 1.76 (3Í, s, Í-7), 2.17–2.90 (5Í, m, Í-4, 5, 6), 3.95
3
(3H, s, OCH ), 3.70 and 3.80 – ÀÂ-system; 3.93 and 4.03 – ÀꢁÂꢁ-system (J = 16.0), 6.73 (1H, s, H-3), 7.09 (1H, m, Í
),
3
arom
13
8.21. (1H, m, Í
), 8.52 (1H, m, Í
). C NMR spectrum (100 MHz, CDCl , ꢅ, ppm): 15.8 (C-7), 27.1 (C-10), 27.6
arom
arom
3
(C-4), 39.7 (C-5), 40.2 (C-6), 40.8 (C-9), 52.5 (C-17), 75.2 (C-8), 118.8 (C-3), 122.9 (C-12), 135.3 (C-2), 139.2 (C-13),
+
144.3 (C-14), 151.7 (C-15), 160.4 (C-11), 165.5 (C-16), 199.1 (C-1). Mass spectrum, m/z (I ,%): 317 [M – Cl] (1), 284 (10),
rel
256 (14), 234 (8), 220 (7), 208 (100), 202 (4), 182 (2), 167 (51), 148 (34), 138 (81), 121 (11), 111 (63), 91 (47), 79 (83), 67 (19),
53 (41).
1
5-[1-(1,3-Benzothiazol-2-ylthio)-2-chloropropan-2-yl]-2-methylcyclohex-2-en-1-one (3). H NMR spectrum
(400 MHz, ÑDCl , ꢅ, ppm, J/Hz): 1.63 and 1.64 (3Í, s, Í-10), 1.73 (3Í, s, Í-7), 2.17–2.90 (5Í, m, Í-4, 5, 6), 2.40, 2.46 (each
3
13
3H, s, ÑÍ -arom), 3.92 and 4.08 – ÀÂ-system; 3.94 and 4.06 – ÀꢁÂꢁ-systemꢆ(J = 13.68), 6.70 (2H, m, H-3, Í
). C NMR
3
arom
spectrum (100 MHz, CDCl , ꢅ, ppm): 15.5 (C-7), 23.7 (C-15, C-16), 26.9 (C-10), 27.7 (C-4), 39.9 (C-6), 41.2 (C-9), 43.1
3
(C-5), 75.3 (C-8), 117.2 (C-14), 135.3 (C-2), 144.3 (C-3), 167.7 (C-12, C-13), 169.6 (C-11), 198.9 (C-1). Mass spectrum,
+
m/z (I ,%): 316 [M – HCl] (1), 268 (100), 218 (8), 232 (72), 218 (20), 206 (80), 200 (68), 186 (16), 167 (69), 148 (20), 138
rel
(88), 121 (12), 91 (50), 79 (78), 67 (18), 53 (42).
278

1
5-{2-Chloro-1-[(4,6-dimethylpyrid-2-yl)thio]propan-2-yl}-2-methylcyclohex-2-en-1-one (4). H NMR spectrum
(300 MHz, ÑDCl , ꢅ, ppm, J/Hz): 1.68, 1.77 (each 3Í, s, Í-7, 10), 2.17–2.90 (5Í, m, Í-4, 5, 6), 3.68 and 3.89 – ÀÂ-system;
3
3.79 and 4.01 – ÀꢁÂꢁ-system (J = 12.0), 6.72 (1H, m, H-3), 7.30 (1H, m, Í
), 7.42 (1H, m, Í
), 7.73 (1H, m, Í
), 7.87
arom
arom
arom
13
(1H, m, Í
). C NMR spectrum (100 MHz, CDCl , ꢅ, ppm): 15.6 (C-7), 26.9 (C-10), 27.6 (C-4), 39.7 (C-6), 39.7 (C-5),
arom
3
41.0 (C-9), 74.2 (C-8), 121.1, 121.7, 124.6, 126.1 (C-13, C-14, C-15, C-16), 135.3 (C-2), 135.4 (C-17), 144.3 (C-3), 152.7
(C-12), 165.3 (C-11), 198.1 (C-1).
1
5-{1-Chloro-2-[(4,6-dimethylpyrid-2-yl)thio]propan-2-yl}-2-methylcyclohex-2-en-1-one (5). H NMR spectrum
(300 MHz, ÑDCl , ꢅ, ppm, J/Hz): 1.60 (3Í, s, Í-7), 1.75 (3Í, q, J = 6.4, Í-10), 2.17–2.90 (5Í, m, Í-4, 5, 6), 4.38 (2H, q,
3
J = 6.4, CH -Cl), 6.95 (1H, m, H-3), 7.30 (1H, m, Í
C NMR spectrum (100 MHz, CDCl , ꢅ, ppm): 16.6 (C-7), 23.6 (C-10), 29.7 (C-4), 39.7 (C-6), 39.7 (C-5), 63.9 (C-9), 57.8
), 7.42 (1H, m, Í
), 7.73 (1H, m, Í
), 7.87 (1H, m, Í
).
2
arom
arom
arom
arom
13
3
(C-8), 121.1, 121.7, 124.6, 126.1 (C-13, C-14, C-15, C-16), 135.3 (C-2), 135.4 (C-17), 144.3 (C-3), 152.7 (C-12), 165.3
(C-11), 198.1 (C-1).
Reaction of 1 with 2-Pyridylselenyl Chloride. Crystalline 2-pyridylselenyl chloride (2 mmol) in CH Cl (4 mL) at
2
2
room temperature was stirred, treated with 1 (2 mmol) dissolved in CH Cl (4 mL), and stirred for 15 d. When the reaction
2
2
was finished, unreacted selenyl chloride was filtered off. The solvent was evaporated (water aspirator). Product 6 was
isolated by column chromatography over silica gel (n-hexane–CH Cl , 60:40) as an odorless yellowish oil. Yield of 6, 68%.
2
2
1
5-[2-Chloro-1-(2-pyridylseleno)propan-2-yl]-2-methylcyclohex-2-en-1-one (6). H NMR spectrum (400 MHz,
ÑDCl , ꢅ, ppm, J/Hz): 1.64, 1.75 (each 3Í, s, Í-7, 10), 2.17–2.90 (5Í, m, Í-4, 5, 6), 3.87 (2H, m, SeCH ), 4.77, 4.79 (each 1Í,
3
2
13
s, Í-9), 6.71 (1H, s, H-3), 7.05 (1H, m, Í
), 7.32 (1H, m, Í
), 7.44 (1H, m, Í
), 8.44 (1H, m, Í
). C NMR
arom
arom
arom
arom
spectrum (100 MHz, CDCl , ꢅ, ppm): 15.6 (C-7), 27.6 (C-10), 27.7 (C-4), 37.4 (C-9), 39.8 (C-6), 43.3 (C-5), 75.7 (C-8), 120.8
3
(C-14), 125.6 (C-12), 135.3 (C-2), 136.2 (C-13), 144.3 (C-11), 149.9 (C-15), 153.4 (C-3), 199.1 (C-1).
Reaction of 1 with 3-Methoxycarbonyl-2-pyridylsulfenyl Chloride in LiClO –Nitromethane. A solution of
4
freshly prepared 3-methoxycarbonyl-2-pyridylsulfenyl chloride (5 mmol) in nitromethane (10 mL) at 20°C was stirred and
treated dropwise with LiClO (5 mmol) in nitromethane (30 mL) and 1 (5 mmol) in nitromethane (10 mL). After 20 d, the
4
reaction mixture was treated with CH Cl (100 mL). The precipitate of LiCl and LiClO was filtered off and rinsed multiple
2
2
4
times with CH Cl . The filtrate was evaporated at reduced pressure. The solvent was removed to afford 2 by column
2
2
chromatography over silica gel (n-hexane–CH Cl , 70:30) as a yellowish oil with a weak odor. Yield of 2, 55%.
2
2
ACKNOWLEDGMENT
The work was performed under the auspices of state support of K(P)FU in order to increase its competency among
the worldwide leading scientific and educational centers.
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