Organylthio(silyl)carbenes

Article abstract of DOI:10.1002/ejoc.200900482

The title carbenes 5 can be generated either from diazo compounds 9 by copper-catalyze d catalysis or from chloro(organylthio)methylsilanes 12 by base-induced α-elimination, This is confirmed, by [2+1] cycloadditions with alkenes to give the cyclopropanes

Full text of DOI:10.1002/ejoc.200900482

FULL PAPER
DOI: 10.1002/ejoc.200900482
Organylthio(silyl)carbenes
Tobias Wagner,[a] Jens Lange,[a] Dirk Grote,[b] Wolfram Sander,[b] Ernst Schaumann,*[a]
Gunadi Adiwidjaja,[c] Arnold Adam,[d] and Jürgen Kopf[e]
Dedicated to Professor Armin de Meijere on the occasion of his 70th birthday
Keywords: Carbenes / Carbanions / Diazo compounds / Cycloaddition / Sulfur heterocycles
The title carbenes 5 can be generated either from diazo com- cific cyclopropane formation, although maleate turns out not
pounds 9 by copper-catalyzed catalysis or from chloro(or- to be a suitable indicator for a stereospecific cycloaddition.
ganylthio)methylsilanes 12 by base-induced α-elimination.
This is confirmed by [2+1] cycloadditions with alkenes to
give the cyclopropanes 4a–d and 14. Product 4a is identical
with the product obtained from carbanion 1c, phenyloxirane,
and styrene, for which a carbene intermediate 5a had been
invoked. On heating in the presence of copper triflate, cyclo-
propane 4a undergoes ring enlargement to the thiochroman
11. With (Z)- or (E)-alkenes 20, carbene 5a gives stereospe-
The suggested singlet character of 5 is confirmed by DFT
calculations (B3LYP/cc-pVTZ). The structures of cyclopro-
panes 4a and 23, as well as those of thiochroman 11 and car-
bene dimer 15, were confirmed by single-crystal X-ray in-
vestigations.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2009)
(Scheme 1).[11] This reaction may be regarded as a homo-
Peterson reaction,[12,13] which should give a cyclopropanone
dithioacetal of type 3, as is the case for the reactions be-
tween carbanions 1a or 1b and oxirane 2. In striking con-
trast, however, the phenylthio-substituted carbanion 1c and
2 yield the isomeric cyclopropane 4f. To account for this
unusual change in the product, we postulated an equilib-
rium between carbanion (“carbenoid”) 1c and phenyl-
Introduction
Since their discovery almost 100 years ago, carbenes have
continued to fascinate chemists because of the unusual na-
ture of their bonding.[1,2] Although most carbenes are only
transient species, it has recently been shown that nucleo-
philic carbenes may be stable, as in the cases of the imid-
azole-derived Arduengo carbenes[3,4] or the phosphorus/sili-
con-substituted Bertrand carbenes.[5–8] Indeed, even op-
tically pure phosphanyl(silyl)carbenes are available.[9] How-
ever, only limited stability at 0 °C was found for amino(silyl)-
carbenes.[10]
The variable effect of silyl substitution on carbene sta-
bility calls for studies of combinations of silylcarbenes ad-
ditionally containing other heteroatom substituents. Here,
we had previously invoked phenylthio(trimethylsilyl)carb-
ene as an intermediate in the domino reaction of the de-
thio(trimethylsilyl)carbene
(5a)
plus
thiophenoxide
(Scheme 1). NMR studies of similar carbanions do not con-
firm such an equilibrium,[14] so the equilibrium may be es-
sentially on the carbenoid side, but once the oxirane is
added, thiophenoxide is removed from the equilibrium at
the same time, liberating carbene 5. In the putative mecha-
nism (Scheme 1), this is followed by nucleophilic attack of
thiophenoxide on the silyloxirane 2, which would be ex-
pected to occur in the usual contrasteric fashion[15] to give
the alkoxide 6. This is identical with the intermediate of
a Peterson olefination[16] of formaldehyde by the anion of
silylated thioanisole. Consequently, the olefination product
7 is formed and offers a chance for [2+1] cycloaddition with
the carbene 5a.
The credibility of this mechanism would definitely be en-
hanced if carbene 5a could be generated independently and
found to react as claimed. In addition, although silyl-[7,10,17]
and organylthiocarbenes[18] are well documented, there is
no literature report on any organylthio(silyl)carbene, and so
a comprehensive study of the properties and the reactivity
of this type of carbene seems highly desirable.
protonated silylthioacetal 1c and the silyloxirane
2
[a] Institut für Organische Chemie, Technische Universität
Clausthal,
Leibnizstrasse 6, 38678 Clausthal-Zellerfeld, Germany
Fax: +49-5323-72-2858
E-mail: ernst.schaumann@tu-clausthal.de
[b] Lehrstuhl für Organische Chemie II, Ruhr-Universität
Bochum, Organische Chemie II Gebäude NC 4/171,
Universitätsstrasse 150, 44801 Bochum, Germany
[c] Mineralogisch-Petrographisches Institut, Universität Hamburg,
Grindelallee 46, 20146 Hamburg, Germany
[d] Institut für Anorganische und Analytische Chemie, Technische
Universität Clausthal,
Paul-Ernst-Strasse 4, 38678 Clausthal-Zellerfeld, Germany
[e] Institut für Anorganische Chemie, Universität Hamburg,
Martin-Luther-King Platz 6, 20146 Hamburg, Germany
5198
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2009, 5198–5207

Organylthio(silyl)carbenes
thermally labile; however, in particular, the methylthio de-
rivatives 9b and 9d are already starting to decompose on
warming of their reaction mixtures to room temperature.
The other examples can be kept in solution at room tem-
perature, but do not survive removal of the solvent. Only
diazo compound 9c can be short-path-distilled, but the dis-
tillate again deteriorates on standing at room temperature,
as shown by gas evolution and a color change.
On addition of copper(I) triflate at room temperature,
the decomposing diazo compounds 9 immediately give gas
evolution. No characterizable products were identified from
these mixtures, but the generation of carbenes 5 was con-
firmed by their trapping as their [1+2] cycloadducts 4a–d in
the presence of styrene. Only the tert-butylthio-substituted
carbene 5e failed to give a cycloadduct but rather an intrac-
table reaction mixture, probably due to steric hindrance. In
the other cases, for a good yield of 4 it is advisable to add
styrene shortly after the addition of the sulfur electrophile
to deprotonated 8. Product 4a had been obtained before in
a reaction similar to that shown in Scheme 1 when thio-
phenoxide was removed from the carbenoid/carbene equi-
librium by addition of styrene oxide, followed by addition
of styrene to trap the simultaneously formed carbene
(Scheme 3).[11] The claimed 1α,2α configuration shown in
Schemes 1 and 2 was confirmed by NOE measurements and
Scheme 1. Regular and irregular homo-Peterson products and the
mechanism of “rearrangement”.
Results and Discussion
Carbene Generation from Diazo Compounds
For an independent synthesis of carbene 5a and conge-
ners, the thermal decomposition of silyldiazomethanes 9
(Scheme 2) was envisaged. The starting materials would
thus be (trimethylsilyl)-[19–21] or [dimethyl(phenyl)silyl]diazo-
methane (8a or 8b).[20] These compounds are known to be
CH-acidic, and their carbanions readily undergo addition
of electrophiles.[22,23] We were pleased to see that this also
holds for sulfur electrophiles such as sulfenyl chlorides or
methyl methanemonothiosulfonate to give the Si/S-substi-
tuted diazo compounds 9a/9c/9e and 9b/9d, respectively
(Scheme 2). The transition from a diazo compound 8 to a
sulfur-containing diazo compound 9 can be conveniently
monitored through a shift of the diazo stretch vibration in
the IR spectrum from 2067 to 2045 cm–1. Products 9 are
Scheme 3. Independent formation and isomerization of cyclopro-
pane 4a.
Scheme 2. Reactions and conditions: (a) BuLi, –78 °C Ǟ room
temp.; (b) MeSSO2Me, –78 °C (for 9b, 9d), (c) tBuSCl, –78 °C (for
9e); (d) PhSCl, –78 °C (for 9a, 9c); (e) CuOTf, room temp.; (f)
PhCH=CH2, room temp.
Figure 1. Crystal structure of cyclopropane 4a (ORTEP plot).
Eur. J. Org. Chem. 2009, 5198–5207
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
5199

E. Schaumann et al.
FULL PAPER
finally by a single-crystal X-ray study of cyclopropane 4a 1,3-zwitterion 10; the subsequent cyclization to 11 follows
(Figure 1). This configuration is sterically favored, but may the route of an intramolecular Friedel–Crafts alkylation.
also be preferred because of a favorable secondary orbital Interestingly, only the shown 2α,4α diastereomer is formed.
interaction, because phenylthiocarbene and styrene give the
analogous cis-cyclopropane.[24]
Carbene Generation by Dehydrochlorination
Isomerization of Cyclopropane 4a
A third pathway to carbenes 5 should be opened up by
the dehydrochlorination of chloro/silyl sulfides 12
(Scheme 4). Here, the initial formation of the carbenoids 13
can be expected and from there the formation of the carb-
enes 5. In the trapping reaction with styrene, an AE mecha-
nism via 13 may compete with the [1+2] cycloadditions in-
volving the finally generated carbene 5 to give the three-
membered-ring compounds 4. In fact, the isolated cyclopro-
panes 4a, 4c, and 4d are in all respects, including configura-
tion, identical with the products 4 formed from the diazo
compounds 9 via carbenes 5, so it seems probable that the
reacting species involved when precursors 12 are used are
also carbenes 5 rather than carbenoids 13.
As with styrene, carbenes 5a and 5b can also be trapped
by cyclohexene, to give the norcarane derivatives 14
(Scheme 4), but for 5c the reaction failed, and with 5a the
yield is low. The reactions are highly diastereoselective, each
giving one isomer with Ͼ90% excess. From the reaction
giving 14a, a considerable amount (25%) of the formal car-
bene dimer 15 was isolated. The (E) configuration of this
alkene was verified by an X-ray structure investigation (Fig-
ure 3).
If the reaction between diazo compound 9a, copper(I)
triflate, and styrene is run above room temperature, the
yield of cyclopropane 4a goes down, but another product –
compound 11 – is formed in increasing amounts. With 9a
at 120 °C, no cyclopropane 4a is found at all, but only prod-
uct 11. A control experiment showed that product 11 is also
formed in very high yield from the primary three-mem-
bered-ring compound 4a, which therefore is obviously an
intermediate in the formation of 11, but this process re-
quires the presence of copper(I) triflate to open the cyclo-
propane ring. The thiochroman structure 11 is suggested by
the spectroscopic evidence and was unambiguously corrob-
orated by an X-ray structure analysis (Figure 2). A possible
mechanism (Scheme 3) involves opening of the C1–C2 bond
of 4a under the influence of the copper catalyst to give the
Figure 2. Crystal structure of thiochroman 11 (ORTEP plot).
Figure 3. Crystal structure of 15 (ORTEP plot).
Scheme 4. Reactions and conditions: (a) BuLi, Et2O, –78 °C; (b) PhCH=CH2, 20 °C; (c) cyclohexene.
5200
www.eurjoc.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2009, 5198–5207

Organylthio(silyl)carbenes
Diastereoselectivity of Carbene Trapping
dition. Control experiments showed that a catalytic amount
of butyllithium (3 mol-%) transforms maleate 16 into a 1:4
mixture with fumarate 17 at room temperature. Possibly,
this is the effect of residual salt in commercial butyllithium.
In the actual carbene-generating experiments, however, sul-
fur nucleophiles in the reaction mixture (e.g., benzenesul-
fenyl chloride contamination in 9a) may well also lead to
the observed change of configuration.
Use of maleate to trap carbenes 5 should in principle
have provided a tool to check on the diastereoselectivities
of the [2+1] cycloadditions. Actually, by Skell’s rule,[25] in-
formation on the multiplicities of the carbenes should be
possible; this principle was very recently successfully ap-
plied to confirm the singlet natures of phosphanyl(silyl)-
carbenes.[26–28] Generation of carbenes 5a or 5b from chloro
sulfides 12 as before (Scheme 4) but with trapping with di-
ethyl maleate (16) in each case gives a [1+2] cycloadduct for
For an unambiguous application of Skell’s rule, 1,4-di-
phenylbut-2-ene (20; Scheme 5) was chosen as an alkene
that could be expected to be both configurationally stable
and easy to handle. After some experimentation, efficient
methods to obtain both diastereomers were found. DIBAL
reduction of 1,4-diphenylbut-2-yne (19) gave the (Z)-alkene,
and sodium-driven reduction of 1,4-diphenylbuta-1,3-diene
(22) provided the (E) isomer (Scheme 5). Both isomers
underwent slow [2+1] cycloaddition with carbene 5a as gen-
erated from thioacetal anion 1c and styrene oxide (cf.
Scheme 1), and two different cycloadducts with complex
3
which the NMR evidence, in particular a JH,H coupling
constant of 6.3 Hz, suggests the trans arrangement of ester
groups. The switch of configuration relative to the em-
ployed cis-ester 16 might indicate a reaction involving a car-
benoid 13 rather than a carbene 5 to give an intermediate
that would allow rotation around the original C=C bond.
The same product was also obtained, however, both when
the carbene 5a was generated from the diazo compound 9a
in our one-pot approach to give an authentic carbene and
when the trans-ester 17 was used as cycloaddition partner.
To account for these results, a triplet character of carbene
1
AAЈBBЈXXЈ H NMR patterns were obtained. For unam-
biguous configuration assignment, we therefore oxidized
5, giving a cycloaddition via a 1,3-diradical, might be con- the putative trans adduct (1α,2α,3β)-21 to the crystalline
sidered. However, when maleate 16 was used in excess and sulfone 23. A single-crystal X-ray study (Figure 4) now al-
the unreacted, reisolated ester was analyzed after the reac- lowed the structure and the trans configuration of the ben-
tion, it was found to be mostly fumarate 17, so maleate zyl groups to be confirmed and therefore implicitly also the
is obviously configurationally unstable under the reaction cis configuration of the benzyl groups in the product 21
conditions and may well isomerize prior to the cycload- obtained from (Z)-20.
Scheme 5. Reactions and conditions: (a) 9a, CuOTf, Et2O, 16 or 17. –78 °C Ǟ room temp.; (b) 12a or 12b, BuLi, Et2O, –78 °C Ǟ room
temp.; (c) DIBAL, toluene, 55 °C; (d) phenyloxirane, 1c, –78 °CǞ0 °C, THF; (e) Na, Et2O, room temp.; (f) mCPBA, CH2Cl2, –20 °C Ǟ
room temp.
Eur. J. Org. Chem. 2009, 5198–5207
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
5201

E. Schaumann et al.
FULL PAPER
Figure 4. Crystal structure of 23 (ORTEP plot).
Physical and Theoretical Evidence for the Multiplicity
Conclusions
Previously, we had invoked organylthio(silyl)carbenes 5
only as intermediates in the reactions between silylthioace-
tal anion 1c and oxiranes such as 2 (Scheme 1) or styrene
oxide (Scheme 3). The current work shows that the carbene
species generated either from diazo precursors 9 or from
chloro sulfides 12 gives identical cycloaddition products
with styrene, in terms both of structure and of configura-
tion, so it can be deduced that the same carbenes 5 are
intermediates in all three approaches. In no case was there
any indication that a carbene 5 may be stable enough for
isolation from the reaction mixture; not even a spectro-
scopic study in solution was feasible. These carbenes are
therefore definitely less stable than the Bertrand carb-
enes,[5–8] indicating that the carbene-stabilizing effect of sul-
fur is much less pronounced than that of phosphorus. Nev-
ertheless, with three convenient methods to generate carb-
ene 5 now to hand, the synthetic value of the multifunc-
tional organylthio(silyl)carbenes 5 should certainly be ap-
preciated.
General expectations based on the heteroatom substitu-
tion[29] and the stereospecific course of the [2+1] cycload-
dition with alkenes 20 both allow singlet character to be
assigned to carbenes 5. However, it seemed desirable to ob-
tain additional evidence for this singlet nature. The diazo
compound 9c was thus irradiated with UV light, but the
reaction product failed to give ESR signals. This indirect
evidence of the singlet character of carbenes 5 was substan-
tiated by DFT calculations for carbene 5d at the B3LYP
level.[30] These calculations gave optimized conformations
of singlet and triplet carbenes (Figure 5) and
a
13.14 kcalmol–1 higher stability of the singlet carbene.
Experimental Section
General: Melting points are uncorrected. 1H and 13C NMR spectra
were recorded with Bruker AC 200 F or ARX 400 instruments in
CDCl3 as solvent. Chemical shifts (δ) were measured in ppm and
coupling constants (J) in Hz. TMS or an internal TMS group was
used as reference for 1H NMR spectra (δ = 0.00 ppm). The solvent
peak was used as reference for 13C NMR spectra (δ = 77.00 ppm).
For assignment of the number of substituents attached to the speci-
fied carbon atom, each carbon atom is described as p or t (primary
or tertiary carbon atom), s (secondary carbon atom), or q (quater-
nary carbon atom), as determined by the DEPT method. When
necessary, NMR spectroscopic data were assigned with the aid of
H,H- and C,H-correlated spectra. MS data were recorded with a
Varian Saturn 2100T or a Hewlett–Packard 5989B instrument;
high-resolution MS (HRMS) measurements were carried out at the
Figure 5. Calculated geometries of the singlet (top) and triplet
forms (bottom) of methylthio(trimethylsilyl)carbene (5d; bond
lengths in Å).
5202
www.eurjoc.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2009, 5198–5207

Organylthio(silyl)carbenes
Institut für Organische Chemie, Leibniz-Universität Hannover, or
at the Institut für Organische Chemie, Universität Göttingen. IR
spectra were recorded with a Bruker Vektor 22 FT-IR spectrome-
ter. Elemental analyses were performed by the Institut für Pharma-
zeutische Chemie, Technische Universität Braunschweig. TLC was
performed on Merck 60 F254 precoated silica plates, and spots were
detected by UV fluorescence or by spraying with a solution of anis-
aldehyde/sulfuric acid in acetic acid/methanol (1:5:10:85) and sub-
sequent heating. Flash chromatography was performed with silica
gel 60 (Merck, 230–400 mesh). Petroleum ether (PE) with the boil-
ing range 60–70 °C was used in the separations. All solvents were
distilled before use. All reactions were carried out under nitrogen.
Colorless oil. 1H NMR (200 MHz): δ = 0.00, 0.02 (each s, 3 H,
SiCH3), 0.80 (dd, J = 5.1, 8.2 Hz, 1 H, CH2 cyclopropane), 0.89
(dd, J = 5.1, 6.5 Hz, 1 H, CH2 cyclopropane), 1.07 (s, 3 H, SCH3),
1.93 (dd, J = 6.5, 8.2 Hz, 1 H, CH cyclopropane), 6.80–7.20 (m,
10 H, aryl H) ppm. 13C NMR (50 MHz): δ = –3.9 (p, 2 C, SiCH3),
15.7 (p, 1 C, SCH3), 17.7 (s, 1 C, CH2 cyclopropane), 19.8 (q, 1 C,
CSSi cyclopropane), 28.8 (t, 1 C, CH cyclopropane), 126.2, 127.5,
127.8, 129.2, 129.3, 134.2 (each t, aryl C), 137.2, 137.5 (each q,
aryl-C) ppm. IR (NaCl): ν = 3067, 3025, 2957, 2919, 1603, 1497,
˜
1454, 1427, 1248, 1170, 1112, 1088, 1067, 1029, 834, 821, 774, 735,
697 cm–1. GC-MS (70eV): m/z (%) = 298 (4.5) [M]+. HR-EI-MS:
calcd: 298.1211; found 298.1211.
[Dimethyl(phenyl)silyl]diazomethane (8b): This compound was pre-
pared analogously to 8a.[20] Yellow liquid, yield 76% (ref.[20] 76%),
b.p. 51 °C (2.3ϫ10–1 mbar). 1H NMR (200 MHz): δ = 0.00 (s, 6
1β-[Dimethyl(phenyl)silyl]-2α-phenyl-1α-(phenylthio)cyclopropane
(4c): This compound was prepared from 8b. Yield 274 mg (76%).
Colorless oil. 1H NMR (400 MHz): δ = 0.00, 0.07 (each s, 3 H,
SiCH3), 1.16 (dd, J = 5.3, 6.8 Hz, 1 H, CH2 cyclopropane), 1.23
(dd, J = 5.3, 8.2 Hz, 1 H, CH2 cyclopropane), 2.08 (dd, J = 6.8,
8.2 Hz, 1 H, CH cyclopropane), 6.71–7.27 (m, 15 H, aryl H) ppm.
13C NMR (100 MHz): δ = –3.8 (p, SiCH3), 19.2 (s, 1 C, CH2 cyclo-
propane), 19.6 (q, CSSi), 28.5 (t, CHPh), 124.9, 126.4, 127.7, 127.8,
128.0, 128.2, 129.2, 129.4, 134.2 (each t, aryl CH), 136.6, 137.3,
H, SiCH3), 2.37 (s, 1 H, CH), 6.95–7.16 (m, 5 H, aryl H) ppm. 13
C
NMR (50 MHz): δ = –2.4 (p, 2 C, SiCH3), 19.5 (t, 1 C, –CN2),
127.9 (t, 2 C, aryl C), 129.5 (t, 1 C), 133.6 (t, 2 C, aryl C), 137.3
(q, 1 C, aryl C) ppm. IR (NaCl): ν = 3215, 3070, 3024, 2959, 2898,
˜
2066, 1591, 1486, 1427, 1262, 1189, 1160, 1114, 1066, 817, 732,
698, 640 cm–1.
138.2 (each q, aryl C) ppm. IR (NaCl): ν = 3065, 3025, 2957, 1582,
˜
General Procedure for the Preparation of Diazomethanes 9a–e: BuLi
in hexanes (1.6 , 0.75 mL, 1.2 mmol) was added dropwise at
–78 °C to 8a[20] or 8b (1 mmol) in diethyl ether (10 mL). After the
system had been stirred for 45 min, 1,1-dimethylethanesulfenyl
chloride,[31] benzenesulfenyl chloride,[32] or S-methyl methane-
monothiosulfonate[33] was added slowly, and stirring was continued
for 10 min. For a good yield of cyclopropane 4, styrene (0.57 mL,
5 mmol) was added at this point and the reaction mixture was al-
lowed to warm to room temp., which for most diazo products 9
already leads to partial decomposition. The reaction mixture was
then poured into water and the aqueous phase was extracted with
diethyl ether (2ϫ). The combined organic phases were dried
(Na2SO4). Because of the thermal lability of the diazo products 9
the filtered solutions were used as such. These reactions led to a
typical shift of the diazo absorption in the IR spectra from ca.
2067 cm–1 to ca. 2048 cm–1. Because of ongoing decomposition no
other reliable data could be obtained.
1497, 1477, 1454, 1438, 1427, 1249, 1112, 1090, 1068, 1026, 922,
821, 776, 736, 695, 651 cm–1. GC-MS (70eV): m/z (%) = 360 (26.8)
[M]+. HR-EI-MS: calcd: 360.1368; found 360.1368.
1α-(Methylthio)-2α-phenyl-1β-(trimethylsilyl)cyclopropane (4d):
This compound was prepared from 9a. Yield 139 mg (59%). Color-
1
less oil. H NMR (200 MHz): δ = 0.00 (s, 9 H, SiCH3), 1.13 (dd,
J = 5.1, 8.1 Hz, 1 H, CH2 cyclopropane), 1.20 (dd, J = 5.1, 6.4 Hz,
1 H, CH2 cyclopropane), 1.58 (s, 3 H, SCH3), 2.25 (dd, J = 6.4,
8.1 Hz, 1 H, CH cyclopropane), 7.07–7.15 (m, 5 H, aryl H) ppm.
13C NMR (50 MHz): δ = –2.3 (p, 3 C, SiCH3), 15.8 (p, 1 C, SCH3),
17.7 (s, 1 C, CH2 cyclopropane), 20.4 (q, 1 C, SCSi), 28.6 (t, 1 C,
CH cyclopropane), 126.2, 127.5, 129.2 (each t, aryl C), 137.8 (q,
aryl C) ppm. IR (NaCl): ν = 3060, 3028, 2954, 2920, 2897, 1604,
˜
1497, 1454, 1247, 1170, 1087, 1065, 1030, 915, 837, 791, 754, 728,
694, 624 cm–1. GC-MS (70eV): m/z (%) = 236 (7) [M]+. HR-EI-
MS: calcd. 236.1055; found 236.1055.
General Procedure for the Reactions between Diazo Compounds 9
and Styrene. Preparation of Cyclopropanes 4a–d: To complete each
reaction with styrene, CuSO3CF3 (ca. 10 mg) was added, and the
mixture was stirred at room temp. for 12 h. The cycloaddition can
be monitored by IR spectroscopy by observing the disappearance
of the absorption at ca. 2048 cm–1. The reaction mixture was then
washed with diluted HCl, and the aqueous phase was extracted
with diethyl ether (2ϫ). The combined organic phases were dried,
and the solvent was evaporated in vacuo. After flash chromatog-
raphy, products 4a–e were obtained.
(2α,4α)-4-Phenyl-2-(trimethylsilyl)thiochroman (11) from Cyclopro-
pane 4a: CuOTf (ca. 10 mg), toluene (5 mL), and 4a (120 mg,
0.4 mmol) were heated at reflux for 18 h. After cooling, the reaction
mixture was washed with diluted HCl, and the aqueous phase was
extracted with diethyl ether (2ϫ). The combined organic phases
were dried (Na2SO4), and the solvents were evaporated in vacuo.
Compound 11 was isolated by flash chromatography. Yield 108 mg
(90%). Colorless solid, m.p. 102–105 °C. 1H NMR (200 MHz): δ =
0.00 (s, 9 H, SiCH3), 2.10 (ddd, J = 12.0, 12.5, 13.5 Hz, 1 H, ring
CH2), 2.42 (ddd, J = 2.3, 4.5, 13.5 Hz, 1 H, ring CH2), 2.85 (dd, J
= 2.3, 12.5 Hz, 1 H, ring CHSi), 4.04 (dd, J = 4.5, 12.0 Hz, 1 H,
ring CHS), 6.53–7.24 (m, 9 H, aryl H) ppm. 13C NMR (50 MHz):
δ = –3.6 (p, 3 C, SiCH3), 28.1 (t, 1 C, CHSSi), 34.9 (s, 1 C, CH2),
47.6 (t, 1 C, CHPh), 123.7, 126.1, 126.3, 126.6, 128.7, 128.8, 130.2
(each t, 1 C, aryl CH), 134.2, 137.4, 145.7 (each q, 1 C, aryl C)
2α-Phenyl-1α-(phenylthio)-1β-(trimethylsilyl)cyclopropane (4a): This
compound was prepared from 9a. Yield 152 mg (51%). Colorless
1
solid, m.p. 58 °C (ref.[11] 56–57 °C). H NMR (400 MHz): δ = 0.00
(s, 9 H, SiCH3), 1.47 (dd, J = 5.3, 6.7 Hz, 1 H, CH2 cyclopropane),
1.60 (dd, J = 5.3, 8.2 Hz, 1 H, CH2 cyclopropane), 2.43 (dd, J =
6.7, 8.2 Hz, CH cyclopropane), 7.08–7.31 (m, 10 H, aryl H) ppm.
13C NMR (100 MHz): δ = –2.3 (p, 3 C, SiCH3), 19.1 (s, 1 C, CH2),
20.0 (q, 1 C, C cyclopropane), 28.2 (t, 1 C, C cyclopropane), 124.8,
126.4, 127.7, 127.9, 128.2 (each t, aryl C), 137.5, 138.4 (each q, 1 C,
aryl C) ppm. GC-MS (70eV): m/z (%) = 298 (23.1) [M]+. C18H22SSi
(298.52): calcd. C 72.42, H 7.43, S 10.74; found C 72.40, H 7.14, S
10.97.
ppm. IR (KBr): ν = 3054, 3025, 2953, 2927, 2901, 2856, 1600, 1586,
˜
1561, 1492, 1471, 1451, 1431, 1247, 1180, 1154, 1133, 1072, 1046,
1030, 1015, 875, 839, 759, 746, 701 cm–1. GC-MS (70eV): m/z (%)
= 298 (11.4) [M]+. C18H22SSi (298.52): calcd. C 72.42, H 7.43, S
10.74; found C 72.40, H 7.14, S 10.97.
[Chloro(organylthio)methyl]silanes 12: The precursor (methylthio)-
(trimethylsilyl)methane was obtained according to ref.,[34] and
1β-[Dimethyl(phenyl)silyl]-1α-(methylthio)-2α-phenylcyclopropane (phenylthio)(trimethylsilyl)methane according to ref.[35] (Phenyl-
(4b): This compound was prepared from 9b. Yield 182 mg (61%).
thio)(dimethylphenylsilyl)methane was prepared in a procedure
Eur. J. Org. Chem. 2009, 5198–5207
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
5203

E. Schaumann et al.
FULL PAPER
analogous to that described in ref.[34] to give a colorless oil (yield
691 cm–1. GC-MS (70eV): m/z (%) = 276 (39.67) [M]+. HR-EI-MS:
1
71%). H NMR (200 MHz): δ = 0.00 (s, 6 H, SiCH3), 1.95 (s, 2 H, calcd. 276.1368; found 276.1368.
SCH2Si), 6.64–7.14 (m, 10 H, aryl H) ppm. 13C NMR (50 MHz):
endo- or -exo-7-(Phenylthio)-exo- or -endo-7-[dimethyl(phenyl)silyl]-
δ = –3.1 (p, 2 C, SiCH3), 17.6 (t, 1 C, SCHSi), 124.7, 126.1, 128.0,
128.7, 129.6, 133.0 (each t, aryl CH), 137.3, 140.1 (each q, aryl C)
ppm. GC-MS (70eV): m/z (%) = 258 (55.5) [M]+. For chlorination,
the corresponding precursor (2.0 mmol) in CCl4 (10 mL) was
stirred with NCS (267 mg, 2 mmol) for 1 d. The formed suc-
cinimide was removed by filtration, and the solvent was evaporated
in vacuo. Products 12a and 12c were purified by Kugelrohr distil-
lation; 12b was used in crude form.
bicyclo[4.1.0]heptane (14b): Yellow oil. Yield 412 mg (61 %). 1H
NMR (200 MHz): δ = 0.00 (s, 9 H, SiCH3), 0.96–1.38 (m, 8 H,
CH2 groups), 1.65–1.76 (m, 2 H, CH groups), 6.82–7.32 (m, 10 H,
aryl H) ppm. 13C NMR (50 MHz): δ = –3.5 (p, 2 C, SiCH3), 18.5
(q, 1 C, CSSi), 19.5 (t, 2 C, bridgehead C), 20.4, 21.9 (each s, 2 C,
CH2), 124.0, 126.1, 127.6, 127.7, 129.0, 134.2 (each t, aryl CH),
137.3, 138.1 (each q, 1 C, aryl C) ppm. IR (NaCl): ν = 3068, 2934,
˜
2853, 1584, 1477, 1439, 1427, 1252, 1115, 1069, 1025, 959, 916,
853, 829, 797, 735, 699, 650 cm–1. GC-MS (70eV): m/z (%) = 338
(50.15) [M]+. HR-EI-MS: calcd. 338.1524; found 338.1524.
[Chloro(phenylthio)methyl]trimethylsilane (12a): Colorless liquid.
1
Yield 450 mg (98%) (ref.[36] 96%). B.p. 90 °C (12 Torr). H NMR
(200 MHz): δ = 0.00 (s, 9 H, SiCH3), 4.65 (s, 1 H, CHCl), 6.97–
7.26 (m, 5 H, aryl H) ppm. GC-MS (70eV): m/z (%) = 230 (13.24)
[M]+.
(E)-1,2-Bis(phenylthio)-1,2-bis(trimethylsilyl)ethene (15): Colorless
1
solid, m.p. 131 °C. Yield 97 mg (25%). H NMR (200 MHz): δ =
0.00 (s, 18 H, SiCH3), 7.07–7.23 (m, 10 H, aryl H) ppm. 13C NMR
(50 MHz): δ = 1.5 (p, 6 C, SiCH3), 125.6, 127.7, 128.9 (each t, aryl
CH), 138.6 (q, 2 C, aryl C), 160.6 (q, 2 C, C=C) ppm. IR (KBr):
[Chloro(phenylthio)methyl]dimethyl(phenyl)silane (12b): Colorless
oil. Crude yield 537 mg (92 %, GC purity 97 %). 1H NMR
(200 MHz): δ = 0.00 (s, 6 H, SiCH3), 4.85 (s, 1 H, SCHClSi), 7.02–
7.20 (m, 10 H, aryl H) ppm. 13C NMR (50 MHz): δ = –4.5, –4.3
(each p, 1 C, SiCH3), 57.9 (t, 1 C, SCHClSi), 127.2, 127.9, 129.0,
129.6, 130.1 (each t, 1 C, aryl CH), 133.0 (q, 1 C, aryl C), 134.4 (t,
ν = 3052, 2946, 2890, 1579, 1473, 1435, 1402, 1245, 1091, 1023,
˜
843, 757, 740, 689 cm–1. GC-MS (70eV): m/z (%) = 388 (13.6)
[M]+. HR-EI-MS: calcd. 388.1171; found 388.1171.
Cyclopropanedicarboxylates 18 from Chlorides 12. General Pro-
cedure: The procedure for the synthesis of 4a/4c/4d and 14a/14b
given above was applied, but diethyl maleate (16; 4 mL, 24.7 mmol)
or fumarate (17; 4 mL, 24.7 mmol) was used as C=C component.
From 12a and 16, diester 18a (yield 26%) was isolated along with
(phenylthio)(trimethylsilyl)methane[37] (10 %), bis(phenylthio)tri-
methylsilylmethane[38] (43%), and 15 (20%). Chloride 12a and 17
gave diester 18a (yield 25%) along with bis(phenylthio)(trimethyl-
silyl)methane[38] (36%).
2 C, aryl CH), 135.5 (q, 1 C, aryl C) ppm. IR (NaCl): ν = 3070,
˜
2960, 1717, 1583, 1480, 1438, 1427, 1252, 1170, 1116, 1091, 1067,
1025, 838, 788, 737, 697, 647 cm–1. GC-MS (70eV): m/z (%) = 292
(14.12) [M]+. HR-EI-MS: calcd: 292.0509; found 292.0508.
[Chloro(methylthio)methyl]trimethylsilane (12c): Colorless liquid.
Yield 168 mg (50%) (ref.[37] 60%). B.p. 45 °C (2.3 mbar; ref.[37] 80–
82 °C/28 Torr). 1H NMR (200 MHz): δ = 0.00 (s, 9 H, SiCH3), 2.06
(s, 3 H, SCH3), 4.36 (s, 1 H, CHCl) ppm. 13C NMR (50 MHz): δ
= –2.8 (p, 3 C, SiCH3), 17.2 (p, 1 C, SCH3), 61.3 (t, 1 C, HCCl)
ppm. GC-MS (70eV): m/z (%) = 168 (8.71) [M]+, 169 (3.79) [M +
1]+, 170 (3.78) [M + 2]+.
Diethyl 3-(Phenylthio)-3-(trimethylsilyl)cyclopropane-trans-1,2-di-
1
carboxylate (18a): Colorless oil. H NMR (200 MHz): δ = 0.00 (s,
9 H, SiCH3), 1.13, 1.19 (each t, J = 7.1 Hz, 3 H, OCH2CH3), 2.62,
2.63 (each d, J = 6.3 Hz, 1 H, CH cyclopropane), 3.96–4.16 (m, 4
H, OCH2CH3), 7.03–7.28 (m, 5 H, aryl H) ppm. 13C NMR
(50 MHz): δ = –0.8 (p, 3 C, SiCH3), 14.1, 14.2 (each p, 1 C,
OCH2CH3), 28.1 (q, 1 C, SCSi), 32.7, 32.4 (each t, 1 C, CH cyclo-
propane), 61.3, 61.4 (each s, 1 C, OCH2CH3), 125.9, 128.6, 128.8
(each t, aryl CH), 136.4 (q, 1 C, aryl C), 168.1, 169.7 (each q, 1 C,
Carbene Generation and Trapping from Silanes 12. General Pro-
cedure: Silane 12 (2 mmol) in diethyl ether (20 mL) was cooled to
–78 °C, BuLi in hexanes (1.6 , 1.5 mL, 2.4 mmol) was slowly
added dropwise to the solution, and the mixture was stirred for
45 min. The yellow reaction mixture was then added by cannula at
room temp. to styrene (4 mL, 35.1 mmol) or cyclohexene (4 mL,
39.5 mmol). After stirring at room temp. for 12 h, the reaction mix-
ture was poured into water, and the aqueous phase was extracted
with diethyl ether (2ϫ). The combined organic phases were dried
(Na2SO4), and the solvents were evaporated in vacuo. The follow-
ing products were obtained after flash chromatography. With sty-
rene, 4a (52%), 4c (48%), or 4d (49%) was obtained; in the synthe-
sis of 4a side products were (phenylthio)(trimethylsilyl)methane[35]
(12%) and bis(phenylthio)(trimethylsilyl)methane[38] (16%). With
cyclohexene, 14a of uncertain configuration was isolated along with
(E)-1,2-bis(phenylthio)-1,2-bis(trimethylsilyl)ethene (15, 25 %),
(phenylthio)(trimethylsilyl)methane[35] (11 %), and bis(phenylthi-
o)(trimethylsilyl)methane[38] (39%), whereas 14b was isolated along
with [dimethyl(phenyl)silyl](phenylthio)methane (29%).
CO CH ) ppm. IR (NaCl): ν = 3059, 2981, 2958, 2934, 2905, 1730,
˜
2
2
1583, 1478, 1439, 1389, 1369, 1317, 1251, 1180, 1095, 1035, 842,
742, 697 cm–1. GC-MS (70eV): m/z (%) = 366 (10.4) [M]+. HR-EI-
MS: calcd. 366.1321; found 366.1321.
Diethyl 3-[Dimethyl(phenyl)silyl]-3-(phenylthio)cyclopropane-trans-
1,2-dicarboxylate (18b): Colorless oil. Yield 188 mg (22%) from 16.
1H NMR (200 MHz): δ = 0.00, 0.13 (each s, 3 H, SiCH3), 0.77,
0.88 (each t, J = 7.1 Hz, 3 H, OCH2CH3), 2.30, 2.46 (each d, J =
6.3 Hz, 1 H, CH cyclopropane), 3.51, 3.76 (each q, J = 7.1 Hz, 2
H, OCH2CH3) 6.74–7.21 (m, 10 H, aryl H) ppm. 13C NMR
(50 MHz): δ = –2.8, –1.5 (each p, 1 C, SiCH3), 13.9, 14.3 (each p,
1 C, OCH2CH3), 27.7 (q, 1 C, SCSi), 33.4, 34.9 (each t, 1 C, CH
cyclopropane), 61.2, 61.3 (each s, 1 C, OCH2CH3), 125.9, 127.5,
128.5, 129.1, 129.3, 134.3 (each t, aryl CH), 136.2, 136.5 (each q,
1 C, aryl C), 167.9, 169.3 (each q, 1 C, CO2CH2) ppm. IR (NaCl):
endo- or -exo-7-(Phenylthio)-exo- or -endo-7-(trimethylsilyl)bi-
cyclo[4.1.0]heptane (14a): Colorless solid, m.p. 80 °C. Yield 66 mg
ν = 2980, 2905, 1730, 1583, 1478, 1439, 1428, 1388, 1368, 1318,
˜
1
(12%). H NMR (200 MHz): δ = 0.00 (s, 9 H, SiCH3), 1.36–1.69
1251, 1182, 1113, 1035, 837, 817, 779, 737, 700 cm–1. GC-MS
(70eV): m/z (%) = 383 (16.6) [M – 45]+. HR-EI-MS: calcd. for [M –
OEt]+: 383.1137; found 383.1137.
(m, 8 H, CH2 groups), 2.0–2.07 (m, 2 H, CH groups), 7.10–7.38
(m, 5 H, aryl H) ppm. 13C NMR (50 MHz): δ = –2.2 (p, 3 C,
SiCH3), 19.3 (q, 1 C, CSSi), 19.3 (t, 2 C, bridgehead C), 20.5, 22.0
(each s, 2 C, CH2), 123.9, 126.2, 128.1 (each t, 2 C, aryl CH), 138.5 Cyclopropanedicarboxylate 18a from Diazo Compound 9a and Male-
(q, 1 C, aryl C) ppm. IR (KBr): ν = 3004, 2930, 2852, 1580, 1477, ate 16: BuLi in hexanes (1.6 , 3.2 mL, 5.1 mmol) was added drop-
˜
1436, 1251, 1172, 1095, 1071, 1025, 963, 922, 866, 833, 737, wise at –78 °C to 8a (0.23 g, 4.25 mmol) in diethyl ether (20 mL).
5204
www.eurjoc.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2009, 5198–5207

Organylthio(silyl)carbenes
After the mixture had been stirred for 45 min, benzenesulfenyl
chloride[32] (0.8 g, 5.5 mmol) was added slowly, and stirring was
continued for 10 min. Ester 16 (4 mL, 24.7 mmol) was added, and
the reaction mixture was allowed to warm to room temp., which
was accompanied by considerable nitrogen evolution. The reaction
mixture was then poured into water, and the aqueous phase was
extracted with diethyl ether (2ϫ). The combined organic phases
were dried (Na2SO4), and the solvent was removed in vacuo. The
product isolated by flash chromatography was in all respects iden-
tical with cyclopropanedicarboxylate 18a obtained above from 12a
and 16. Yield 42%.
(1.6 , 2.3 mL, 3.68 mmol) was added dropwise at –78 °C to pro-
tonated 1c (1.000 g, 3.28 mmol) in absolute THF (10 mL), and the
mixture was stirred for 40 min. It was then allowed to warm to
0 °C over 1 h and kept at this temperature for another 30 min.
Phenyloxirane (0.39 mL, 3.41 mmol) and (Z)- or (E)-20 (1.60 g,
7.68 mmol) were then added. After having been stirred at room
temp. for 2 d, the reaction mixture was diluted with diethyl ether
(50 mL) and washed with water (4ϫ25 mL). The organic phase
was dried (Na2SO4), and the solvents were removed in vacuo. Flash
chromatography gave the following products.
(1α,2α,3α)-2,3-Dibenzyl-1-(phenylthio)-1-(trimethylsilyl)cyclopro-
pane from (Z)-20: Yield 224 mg (17%). Colorless oil. The same
product was obtained from chloromethylsilane 12a (138.5 mg,
0.6 mmol) and (Z)-20 (250 mg, 1.2 mmol) by the general procedure
of Scheme 4, but with lithium tetramethylpiperidide as base at
(Z)-1,4-Diphenylbut-2-ene [(Z)-20]: This compound was prepared
according to a procedure analogous to that described in ref.[39] DI-
BAL-H in toluene (20% by weight, 18.16 mL, 21.57 mmol) was
added dropwise at –20 °C to alkyne 19 (2.670 g, 12.92 mmol). The
reaction mixture was then kept at 55 °C for 16 h. After the mixture
had been cooled to 0 °C, methanol (2.5 mL) was added carefully,
followed by diluted H2SO4 (2 mL). This resulted in solidification
of the reaction mixture. The product was thoroughly extracted with
diethyl ether, and the organic phase was washed with water, satu-
rated aqueous NaHCO3, and again with water. The combined or-
ganic phases were dried (Na2SO4), and the solvents were evapo-
1
room temp. Yield 24 mg (10%). H NMR (400 MHz): δ = 0 (s, 9
H, SiCH3), 1.82 (ddd, J = 6.7, 4.6, 2.2 Hz, 2 H, CH cyclopropane),
3.19 (ddd, J = 15.2, 4.6, 2.2 Hz, 4 H, CH2Ph), 7.21–7.45 (m, 15 H,
aryl H) ppm. 13C NMR (100 MHz): δ = –2.3 (p, 3 C, SiCH3), 19.0
(q, 1 C, C cyclopropane), 27.4 (t, 2 C, CH cyclopropane), 30.7 (s,
2 C, CH2Ph), 124.4, 125.9, 126.7, 128.2, 128.3, 128.7 (each t, aryl
CH), 138.2, 141.2 (each q, aryl C) ppm. IR (NaCl): ν = 3061, 3027,
˜
1
rated in vacuo to give a colorless liquid (2.462 g, 91%). H NMR
2954, 2898, 1602, 1583, 1495, 1478, 1454, 1439, 1250, 1085, 1073,
1026, 980, 879, 837, 737, 697 cm–1. GC-MS (70eV): m/z (%) = 402
(3) [M]+, 311 (100) [M – Bn]+, 237 (11), 219 (59), 91 (30) [Bn]+, 73
(200 MHz): δ = 3.52 (d, J = 5.5 Hz, 4 H, CH2), 5.71 (ddd, J = 5.8,
4.6, 1.2 Hz, 2 H, CH=CH), 7.15–7.34 (m, 10 H, H aryl) ppm. 13C
NMR (50 MHz): δ = 33.5 (s, 2 C, CH2), 126.0 (t, 2 C, CH=CH), (77) [SiCH3]+, 65 (12) [C5H5]+. HR-EI-MS: calcd: 402.1837; found
128.4, 128.5, 129.1 (each t, aryl CH), 140.8 (q, 2 C, aryl C) ppm.
402.1836.
IR (NaCl): ν = 3084, 3062, 3026, 2910, 2844, 1945, 1601, 1494,
˜
(1α,2α,3β)-2,3-Dibenzyl-1-(phenylthio)-1-(trimethylsilyl)cyclopro-
pane from (E)-20: Yellow oil. Crude yield 180 mg (GC purity 73%,
yield 10%). For full characterization the product was oxidized to
the sulfone 23.
1453, 1396, 1287, 1182, 1155, 1109, 1074, 1030, 901, 834, 736,
697 cm–1.
(E)-1,4-Diphenylbut-2-ene [(E)-20]: This compound was obtained
from diene 22 by reduction with sodium essentially as described in
ref.[40] Yield 2.15 g (71%; ref.[40] 92%) from 3.00 g (14.54 mmol) of
22. M.p. 41 °C (ref.[40] 43–45 °C).
(1α,2α,3β)-2,3-Dibenzyl-1-(phenylsulfonyl)-1-(trimethylsilyl)cyclo-
propane (23): m-CPBA (170 mg, 0.99 mmol) in CH2Cl2 (2 mL) was
added dropwise at –20 °C to (1α,2α,3β)-21 (104 mg, 0.26 mmol) in
CH2Cl2 (2 mL). The mixture was allowed to warm slowly to room
temp. and stirred for 1 d. It was then washed with saturated aque-
Epimeric 2,3-Dibenzyl-1-(phenylthio)-1-(trimethylsilyl)cyclopro-
panes (21) from Carbanion 1c. General Procedure: BuLi in hexanes
Table 1. X-ray data for compounds 4a, 11a, 15, and 23.
Parameter
4a
11a
15
23
Empirical formula
Formula mass
Crystal system
Space group
C18H22SSi
298.51
orthorhombic
P212121
C18H22SSi
298.51
triclinic
P1
293
0.248
C20H28S2Si2
388.72
monoclinic
P21/c
223(2)
0.356
C26H30O2SSi
434.65
monoclinic
P21/c
153
0.208
Temperature [K]
223(2)
Absorption coefficient µ [mm–1] 0.25
Crystal size [mm]
Angle range [°]
Lattice parameters
a [Å]
b [Å]
c [Å]
0.5ϫ0.3ϫ0.25
2.60–26.37
0.38ϫ0.27ϫ0.19
1.73–27.53
0.4ϫ0.4ϫ0.15
2.56–26.36
0.45ϫ0.24ϫ0.22
1.95–28.02
6.3186(5)
14.4362(9)
18.613(2)
90
6.403(10)
11.775(10)
12.280(10)
74.14
6.4989(4)
19.079(1)
9.0728(6)
90
7.5703(5)
27.540(2)
11.3397(7)
90
α [°]
β [°]
γ [°]
90
90
80.96
75.29
105.258(5)
90
94.213(1)
90
Cell volume V [Å3]
Formula units Z
Calculated density [gcm–3]
Measured reflections
Independent reflections
R1 [I Ͼ 2σ (I)]
wR2 [I Ͼ 2σ (I)]
Goodness of fit on F2
CCDC-
1697.9(2)
4
1.168
16152
3469
0.027
0.060
1.041
713344
857.58(10)
2
1.156
9835
3932
0.0458
0.1236
0.961
1085.3(1)
2
1.189
10951
2203
0.0324
0.0717
1.128
2357.8(3)
4
1.224
5561
4466
0.0366
0.0955
0.995
713435
713345
714156
Eur. J. Org. Chem. 2009, 5198–5207
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
5205

E. Schaumann et al.
FULL PAPER
[7] D. Bourissou, O. Guerret, F. P. Gabbai, G. Bertrand, Chem.
Rev. 2000, 100, 39–91.
[8] Y. Canac, M. Soleihavoup, S. Conejero, G. Bertrand, J. Or-
ganomet. Chem. 2004, 689, 3857–3865.
[9] J. Krysiak, C. Lyon, A. Baceiredo, H. Gornitzka, M. Miko-
lajczyk, G. Bertrand, Chem. Eur. J. 2004, 10, 1982–1986.
[10] Y. Canac, S. Conejero, B. Donnadieu, W. W. Schoeller, G. Ber-
trand, J. Am. Chem. Soc. 2005, 127, 7312–7313.
[11] E. Schaumann, C. Friese, Tetrahedron Lett. 1989, 30, 7033–
7036.
[12] C. Friese in Houben-Weyl, Methods of Organic Synthesis (Ed.:
A. de Meijere), Thieme, Stuttgart, 1997, vol. E17a, pp. 838–
841.
[13] E. Schaumann, A. Kirschning, Synlett 2007, 177–190.
[14] H. J. Reich, R. R. Dykstra, Angew. Chem. 1993, 105, 1489–
1491; Angew. Chem. Int. Ed. Engl. 1993, 32, 1469–1470; H. J.
Reich, R. R. Dykstra, J. Am. Chem. Soc. 1993, 115, 7041–7042.
[15] P. F. Hudrlik, A. M. Hudrlik, Adv. Silicon Chem. 1993, 2, 1–
89, especially p. 12.
ous NaHCO3 (3ϫ) and dried (MgSO4). The solvent was evapo-
rated in vacuo, and the residue was purified by flash chromatog-
raphy (petroleum ether/ethyl acetate, 50:1) to give a colorless solid
1
(100 mg, 88%). M.p. 138 °C. H NMR (400 MHz): δ = –0.07 (s, 9
H, SiCH3), 1.76 (ddd, J = 8.8, 7.4, 4.9 Hz, 1 H, CH cyclopropane),
2.55 (dd, J = 14.0, 9.5 Hz, 1 H, CH2Ph), 2.68 (ddd, J = 9.4, 7.3,
5.2 Hz, 1 H, CH cyclopropane), 2.98 (dd, J = 13.9, 5.1 Hz, 1 H,
CH2Ph), 3.26 (dd, J = 14.6, 8.9 Hz, 1 H, CH2Ph), 3.35 (dd, J =
14.7, 4.9 Hz, 1 H, CH2Ph), 7.04–7.23 (m, 10 H, aryl H), 7.44–7.50
(m, 2 H, aryl H), 7.53–7.59 (m, 1 H, aryl H), 7.80–7.84 (m, 2 H,
aryl H) ppm. 13C NMR (100 MHz): δ = 0.78 (p, 3 C, SiCH3), 34.1
(s, 1 C, CH2Ph), 35.0, 35.6 (each t, 1 C, CH cyclopropane), 35.7 (s,
1 C, CH2Ph), 41.3 (q, 1 C, C cyclopropane), 126.0, 126.5, 127.8,
128.4, 128.6, 128.9, 133.0 (each t, aryl CH), 139.7, 141.1, 143.2
(each q, 1 C, aryl C) ppm. IR (KBr): ν = 3026, 2965, 2908, 1600,
˜
1494, 1455, 1444, 1411, 1283, 1253, 1145, 1098, 1083, 1014, 969,
921, 903, 843, 800, 751, 736, 725, 700, 689, 646, 625 cm–1. MS
(70eV): m/z (%) = 343 (73) [M – Bn]+, 327 (88), 199 (35), 183 (27),
135 (85), 104 (70) [C8H8]+, 91 (63) [Bn]+, 73 (100) [SiCH3]+. HR-
ESI-MS: calcd. 498.1899 [M + Na + CH3CN]+; found 498.1902.
[16] L. F. van Staden, D. Gravestock, D. J. Ager, Chem. Soc. Rev.
2002, 31, 195–200.
[17] H. Tomoika, Houben-Weyl Methods of Organic Synthesis (Ed.:
M. Regitz), Thieme, Stuttgart, 1989, vol. E19b, pp. 1410–1446.
[18] K. Schank, Houben-Weyl Methods of Organic Synthesis (Ed.:
M. Regitz), Thieme, Stuttgart, 1989, vol. E19b, pp. 1682–1713.
[19] S. Mori, I. Sakai, T. Aoyama, T. Shiori, Chem. Pharm. Bull.
1982, 30, 3380–3382.
X-ray Structural Investigation of Products 4a, 11a, 15, and 23: A
suitable single crystal of each of the title compounds was selected
under a polarization microscope and mounted in a glass capillary
(d = 0.5 mm). The crystal structures were determined by X-ray dif-
fraction analysis. Single-crystal intensity data were collected for 4a
and 15 by use of a STOE IPDS II instrument and for 11a and 23
by use of an Enraf–Nonius Kappa CCD fitted with a rotating an-
ode (Mo-Kα radiation, λ = 0.71073 Å) [T as given in Table 1]. The
crystal structures were solved by direct methods by use of
SHELXS-97 and refined by use of alternating cycles of least-
squares refinements against F2 (SHELXL-97).[41] All non-H atoms
were located in difference Fourier maps and were refined with an-
isotropic displacement parameters. The H positions were deter-
mined by a final difference Fourier synthesis. The resulting param-
eters are reported in Table 1. CCDC-713344 (4a), -713345 (15),
-713435 (11a), and -714156 (23) contain the supplementary crystal-
lographic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
[20] T. Shiori, A. Aoyama, S. Mori, Org. Synth. 1989, 68, 1–7.
[21] N. S. Hodnett, Synlett 2003, 2095–2096.
[22] D. Seyferth, T. C. Flood, J. Organomet. Chem. 1971, 29, C25–
C28.
[23] J. Podlech, J. Prakt. Chem. 1998, 340, 679–682.
[24] W. E. Truce, V. V. Badiger, J. Org. Chem. 1964, 29, 3277–3280.
[25] R. C. Woodward, P. S. Skell, J. Am. Chem. Soc. 1959, 81, 3383–
3386; P. S. Skell, Tetrahedron 1985, 41, 1427–1428.
[26] S. Goumri-Magnet, T. Kato, H. Gornitzka, A. Baceiredo, G.
Bertrand, J. Am. Chem. Soc. 2000, 122, 4464–4470.
[27] J. Krysiak, T. Kato, H. Gornitzka, A. Baceiredo, M. Miko-
lajczyk, G. Bertrand, J. Org. Chem. 2001, 66, 8240–8242.
[28] B. Lecea, M. Ayerbe, A. Arrieta, F. P. Cossio, V. Branchadell,
R. M. Ortuno, A. Baceiredo, J. Org. Chem. 2007, 72, 357–366.
[29] W. Kirmse, Angew. Chem. 2004, 116, 1799–1801; Angew. Chem.
Int. Ed. 2004, 43, 1767–1769.
[30] A. D. Becke, J. Chem. Phys. 1993, 98, 5648–5652.
[31] I. W. J. Still, G. W. Kutney, D. McLean, J. Org. Chem. 1982,
47, 560–561.
[32] H. J. Reich, R. C. Holtan, C. Bolm, J. Am. Chem. Soc. 1990,
112, 5609–5617.
[33] D. Scholz, Synthesis 1983, 944–945.
[34] D. J. Peterson, J. Org. Chem. 1967, 32, 1717–1720.
[35] B.-Th. Gröbel, D. Seebach, Chem. Ber. 1977, 110, 852–866.
[36] C. J. Urch, S. K. Patel, I. Fleming, J. Chem. Soc. Perkin Trans.
1 1989, 115–124.
[37] S. Shimizu, M. Ogata, Tetrahedron 1989, 45, 637–642.
[38] D. Seebach, M. Kolb, B.-Th. Gröbel, Chem. Ber. 1973, 106,
2277–2290.
[39] G. Wilke, H. Müller, Chem. Ber. 1956, 89, 444–447.
[40] P. Crotti, M. Ferretti, F. Macchia, A. Stoppioni, J. Org. Chem.
1984, 49, 4706–4711.
[41] G. M. Sheldrick, Acta Crystallogr., Sect. A 2008, 64, 112–122.
[42] C. Lee, W. Yang, R. G. Parr, Phys. Rev. B: Condens. Matter
1988, 37, 785–789.
Calculations: Optimized geometries of singlet and triplet 5d were
calculated at the B3LYP level[30,42,43] with employment of Dun-
ning’s cc-pVTZ basis set.[44] A spin-unrestricted formalism was
used. All DFT calculations were carried out with Gaussian 03.[45]
The natures of the stationary points were assessed by means of
vibrational frequency analysis.
Acknowledgments
We thank the Fonds der Chemischen Industrie (Frankfurt) for gen-
erous support of our work.
[1] H. Staudinger, O. Kupfer, Ber. Dtsch. Chem. Ges. 1912, 45,
501–509.
[2] W. v. E. Doering, A. K. Hoffmann, J. Am. Chem. Soc. 1954,
76, 6162–6165.
[43] B. Miehlich, A. Savin, H. Stoll, H. Preuss, Chem. Phys. Lett.
1989, 157, 200–206.
[3] R. L. Harlow, M. Kline, A. J. Arduengo III, J. Am. Chem. Soc.
1991, 113, 361–363.
[4] A. J. Arduengo III, Acc. Chem. Res. 1999, 32, 913–921.
[5] A. Igau, H. Grutzmacher, A. Baceiredo, G. Bertrand, J. Am.
Chem. Soc. 1988, 110, 6463–6466.
[6] A. Igau, A. Baceiredo, G. Trinquier, G. Bertrand, Angew.
Chem. 1989, 101, 617–618; Angew. Chem. Int. Ed. Engl. 1989,
28, 621–622.
[44]
[45]
T. H. Dunning Jr, J. Chem. Phys. 1989, 90, 1007–1023.
M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria,
M. A. Robb, J. R. Cheeseman, J. A. Montgomery Jr, T. Vreven,
K. N. Kudin, J. C. Burant, J. M. Millam, S. S. Iyengar, J. Tom-
asi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega,
G. A. Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota,
5206
www.eurjoc.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2009, 5198–5207

Organylthio(silyl)carbenes
R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda,
O. Kitao, H. Nakai, M. Klene, X. Li, J. E. Knox, H. P. Hratch-
ian, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gom-
perts, R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C.
Pomelli, J. W. Ochterski, P. Y. Ayala, K. Morokuma, G. A.
Voth, P. Salvador, J. J. Dannenberg, V. G. Zakrzewski, S. Dap-
prich, A. D. Daniels, M. C. Strain, O. Farkas, D. K. Malick,
A. D. Rabuck, K. Raghavachari, J. B. Foresman, J. V. Ortiz, Q.
Cui, A. G. Baboul, S. Clifford, J. Cioslowski, B. B. Stefanov,
G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R. L. Martin,
D. J. Fox, T. Keith, M. A. Al-Laham, C. Y. Peng, A. Nanayak-
kara, M. Challacombe, P. M. W. Gill, B. Johnson, W. Chen,
M. W. Wong, C. Gonzalez, J. A. Pople, Gaussian 03, Re-
vision C.02, Gaussian, Inc., Wallingford, CT, 2004.
Received: May 4, 2009
Published Online: September 4, 2009
Eur. J. Org. Chem. 2009, 5198–5207
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
5207