Generation of previously unknown (alk-1-ynyl)organylthiocarbenes by the γ-elimination of HCl from 1-substituted 3-organyl-1-chloropropadienes under the action of bases

Article abstract of DOI:10.1070/MC2003v013n02ABEH001714

Previously unknown (alk-1-ynyl)organylthiocarbenes were generated from 1-substituted 1-chloro-3-organylthiopropadienes 1 as a result of HCl elimination under the action of potassium tert-butoxide.

Full text of DOI:10.1070/MC2003v013n02ABEH001714

, 2003, 13(2), 52–53
Generation of previously unknown (alk-1-ynyl)organylthiocarbenes by the
γ-elimination of HCl from 1-substituted 3-organyl-1-chloropropadienes under
the action of bases
Konstantin N. Shavrin,* Valentin D. Gvozdev and Oleg M. Nefedov*
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian Federation.
Fax: +7 095 135 5328; e-mail: gvozdev@excite.com
10.1070/MC2003v013n02ABEH001714
Previously unknown (alk-1-ynyl)organylthiocarbenes were generated from 1-substituted 1-chloro-3-organylthiopropadienes 1 as
a result of HCl elimination under the action of potassium tert-butoxide.
By now, a considerable number of (alk-1-ynyl)carbenes with
different substituents at the carbene centre, which were generated
using various methods, were described.1–4 In particular, (alk-
1-ynyl)halocarbenes were generated under the action of bases
as a result of either α-elimination of a hydrogen halide mole-
cule from 1,1-dihaloalk-2-ynes5 or γ-elimination of HCl from
1,1-dichloroalka-1,2-dienes.6 Taking into account analogies in
the behaviours of a halogen atom and an organylthio group
in the generation of corresponding halo- and organylthio-
carbenes, we attempted to obtain previously unknown (alk-1-
ynyl)organylthiocarbenes in a similar manner.
We tried to prepare 1-organylthio-1-chloroalk-2-ynes, which
are potential precursors of (alk-1-ynyl)organylthiocarbenes, by
the action of N-chlorosuccinimide in CCl4 on sulfides 1a–c.
However, previously unknown 1-substituted 3-organylthio-
1-chloropropadienes† 2a–c were obtained instead of the expected
products (Scheme 1).
and formation of carbenes 4a–c [similarly to the generation of
(alk-1-ynyl)chlorocarbenes from 1,1-dichloropropadienes6],
which do not add to ethylene derivatives under the reaction
conditions; (c) isomerization of carbenes 4a–c to more highly
reactive carbenes 5a–c according to the scheme proposed
previously1 for the rearrangement of alk-1-ynylcarbenes; and
(d) formation of a three-carbon ring as a result of the addition of
carbenes 5a–c to ethylene derivatives.
Thus, the addition of organylthio(alk-1-ynyl)carbenes to
alkenes can be applied as a direct method for the synthesis
of 1-(organylthio)-1-(alk-1-ynyl)cyclopropanes. Previously,
1-(organylthio)-1-(alk-1-ynyl)cyclopropanes were prepared
starting from 2,3-disubstituted oxiranes and 1-lithio-phenyl-
thioprop-2-yne as a result of a three-step reaction7 or from
1-(trichlorovinyl)-1-chlorocyclopropanes.8
This work was supported by the Russian Foundation for Basic
Research (grant nos. 01-03-32674 and 00-15-97387).
Cl
H
i
R1
C
‡
The structures of cyclopropanes 6a–d were assigned on the basis of
SR2
SR2
R1
their 1H and 13C NMR spectra (200 and 50 MHz for 1H and 13C, respec-
tively; CDCl3) as well as elemental analysis.
1a–c
2a–c
For 6a: 28% from chloride 2a and 2,3-dimethylbut-2-ene. 1H NMR, d:
1.17 (s, 6H, 2Me), 1.19 (s, 6H, 2Me), 1.21 (s, 9H, 3Me in But), 2.12 (s,
3H, SMe). 13C NMR, d: 14.7 (SMe), 18.0 (2Me), 20.2 (2Me), 27.7
(CMe3), 29.5 (2CMe2), 31.4 (3Me in But), 34.2 (CSMe in cyclo-C3),
77.8, 90.8 (CºC). Found (%): C, 75.26; H, 10.56. Calc. for C14H24S
(%): C, 74.99; H, 10.70.
a R1 = But, R2 = Me
b R1 = But, R2 = p-Tolyl
c R1 = Ad, R2 = Me
Scheme 1 Reagents and conditions: i, N-chlorosuccinimide, CCl4, 20 °C.
1
For 6b: 49% from chloride 2b and 2,3-dimethylbut-2-ene. H NMR,
The subsequent treatment of allenes 2a–c with potassium
tert-butoxide in hexane at –20 °C in the presence of a threefold
to fivefold excess of 2,3-dimethylbut-2-ene or styrene resulted
in the formation of 1-(alk-1-ynyl)-1-methylthio- and 1-(alk-
1-ynyl)-1-p-tolylthiocyclopropanes‡ 6a–d in 18–49% yield
(Scheme 2). The structures of prepared compounds 6a–d were
d: 1.19 (s, 9H, 3Me in But), 1.30 (s, 6H, 2Me), 1.33 (s, 6H, 2Me), 2.37
(s, 3H, Me in p-tolyl), 7.12 (br. d, 2H, o-H in cyclo-C6H4, J 8.3 Hz),
7.31 (br. d, 2H, m-H in cyclo-C6H4, J 8.3 Hz). 13C NMR, d: 18.8 (2Me),
20.4 (2Me), 21.1 (Me in p-tolyl), 27.6 (CMe3), 30.5 (2CMe2), 31.2
(3Me in But), 34.0 (CSMe in cyclo-C3), 78.8, 90.7 (CºC), 128.4, 129.1
(C-2, C-3, C-5, C-6 in cyclo-C6H4), 133.5, 134.7 (C-1, C-4 in cyclo-
C6H4). Found (%): C, 80.14; H, 9.11. Calc. for C20H28S (%): C, 79.98;
H, 9.32.
1
assigned on the basis of elemental analyses as well as H and
13C NMR spectra.
The fact that adducts 6a–d were formed from styrene and
2,3-dimethylbut-2-ene by addition of carbenes 5a–c (rather
than 4a–c) allows one to propose a mechanistic scheme. This
scheme includes (a) deprotonation of allenes 2a–c by ButOK
leading to the anions 3a–c; (b) elimination of the chloride ion
For 6c (isomer ratio = 5:1): 18% from chloride 2a and styrene. For the
major isomer: 1H NMR, d: 1.31 (s, 9H, But), 1.48 (dd, 1H, 1H from CH2
in cyclo-C3H3, J 5.3 Hz, J 7.5 Hz), 1.63 (dd, 1H, 1H from CH2 in cyclo-
C3H3, J 5.3 Hz, J 8.6 Hz), 2.39 (s, 3H, SMe), 2.72 (dd, 1H, CHPh,
J 7.5 Hz, J 8.6 Hz), 7.25–7.35 (m, 5H, Ph). 13C NMR, d: 15.8 (SMe),
22.3 (CH2 in cyclo-C3H3), 27.2 (CSMe in cyclo-C3H3), 28.5 (CMe3),
30.9 (3Me in But), 34.1 (CHPh), 81.0, 86.7 (CºC), 126.5, 127.5, 128.9
†
Spectroscopic data for allenes 2a–c.
For 2a: H NMR, d: 1.17 (s, 9H, 3Me), 2.15 (s, 3H, SMe), 6.24 (s,
1
1
(Ph), 135.8 (C-1 in Ph). For a minor isomer: H NMR, d: 1.26 (s, 9H,
1H, =CH). 13C NMR, d: 14.2 (SMe), 28.6 (3Me), 37.7 (CMe3), 99.6
(MeSCH=), 122.9 [But(Cl)C=], 192.5 (=C=).
But), 1.20–1.39 (m, 2H, CH2 in cyclo-C3H3), 2.41 (s, 3H, SMe), 2.51
(dd, 1H, CHPh, J 6.3 Hz, J 9.1 Hz), 7.25–7.35 (m, 5H, Ph). 13C NMR, d:
16.2 (SMe), 23.4 (CH2 in cyclo-C3H3), 23.8 (CSMe in cyclo-C3H3), 28.2
(CMe3), 30.9 (3Me), 35.2 (CHPh), 75.2, 88.1 (CºC), 126.1, 127.3,
128.2 (Ph), 137.1 (C-1 in Ph). Found (%): C, 78.45; H, 8.34. Calc. for
C16H20S (%): C, 78.68; H, 8.19.
For 2b: 1H NMR, d: 0.99 (s, 9H, 3Me), 2.38 (s, 3H, Me), 6.28 (s, 1H,
=CH–), 7.21 (br. d, 2H, o-H in cyclo-C6H4, J 8.2 Hz), 7.39 (br. d, 2H,
m-H in cyclo-C6H4, J 8.2 Hz). 13C NMR, d: 21.0 (Me), 28.0 (3Me), 37.1
(CMe3), 99.6 (–SCH=), 121.8 [But(Cl)C=], 127.7 (C-1 in cyclo-C6H4),
129.4, 133.5 (C-2, C-3, C-5, C-6 in cyclo-C6H4), 138.5 (C-4 in cyclo-
C6H4), 193.9 (=C=).
For 6d: 39% from chloride 2c and 2,3-dimethylbut-2-ene. 1H NMR, d:
1.17 (s, 6H, 2Me), 1.18 (s, 6H, 2Me), 1.67 (br. s, 6H, 3CH2 in Ad), 1.84
(br. s, 6H, 3CH2 in Ad), 1.91 (br. s, 3H, 3CH in Ad), 2.13 (s, 3H, SMe).
13C NMR, d: 14.9 (SMe), 18.0 (2Me), 20.2 (2Me), 28.1 (3CH in Ad),
29.5 (2CMe2), 29.8 (CºCC in Ad), 34.3 (CSMe in cyclo-C3), 36.4
(3CH2 in Ad), 43.5 (3CH2 in Ad), 78.0, 90.9 (CºC). Found (%): C,
79.64; H, 9.73. Calc. for C20H30S (%): C, 79.47; H, 9.92.
For 2c: 1H NMR, d: 1.63 (br. s, 6H, 3CH2 in Ad), 1.70 (br. s, 6H,
3CH2 in Ad), 1.98 (br. s, 3H, 3CH in Ad), 2.11 (s, 3H, SMe), 6.20 (s,
1H, =CH–). 13C NMR, d: 14.0 (SMe), 28.0 (3CH in Ad), 36.3 (3CH2 in
Ad), 38.5 [=(Cl)CC in Ad], 40.6 (3CH2 in Ad), 99.7 (MeSCH=), 122.7
[Ad(Cl)C=], 192.6 (=C=).
– 52 –

, 2003, 13(2), 52–53
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R6
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R6
R4
R2S
SR2
R1
SR2
R1
R5
R1
4a–c
5a–c
6a–d
–
R1 = But, R2 = Me
2 5 a
b R1 = But, R2 = p-Tolyl
R1 = Ad, R2 = Me
c
R1 = But, R2 = R3 = R4 = R5 = R6 = Me
6 a
b R1 = But, R2 = p-Tolyl, R3 = R4 = R5 = R6 = Me
c R1 = But, R2 = Me, R3 = Ph, R4 = R5 = R6 = H
R1 = Ad, R2 = R3 = R4 = R5 = R6 = Me
d
Scheme 2 Reagents and conditions: i, ButOK, hexane, 20 °C.
Received: 15th January 2003; Com. 03/2040
– 53 –