Reaction of cyclopropylcarbene-metal complexes with nucleophiles, halogens and HX

Article abstract of DOI:10.1016/j.jorganchem.2005.07.044

The reaction of halogens, pseudohalogens, and HX with cyclopropyl(phenylthio)carbene-chromium complexes leads to the formation of 1,4-dihalo-1-thiophenyl-1-butene systems with a moderate-high degree of stereocontrol in the formation of the alkene. A mecha

Full text of DOI:10.1016/j.jorganchem.2005.07.044

Journal of Organometallic Chemistry 690 (2005) 5759–5776
www.elsevier.com/locate/jorganchem
Reaction of cyclopropylcarbene–metal complexes with
nucleophiles, halogens and HX
a
a
b
a
Margaret D. Reid , Liz Tirado , Jianwei Zhang , Nwamara Dike ,
b,
*
James W. Herndon
a
Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742-2021, USA
Department of Chemistry and Biochemistry, New Mexico State University, MSC 3C, Las Cruces, NM 88003, USA
b
Received 1 June 2005; accepted 11 July 2005
Available online 30 August 2005
Abstract
The reaction of halogens, pseudohalogens, and HX with cyclopropyl(phenylthio)carbene-chromium complexes leads to the for-
mation of 1,4-dihalo-1-thiophenyl-1-butene systems with a moderate-high degree of stereocontrol in the formation of the alkene. A
mechanism involving electrophilic activation of the carbene complex followed by nucleophilic attack at the cyclopropane carbon has
been proposed.
Ó 2005 Elsevier B.V. All rights reserved.
Keywords: Fischer carbene; Halogens; Nucleophilic addition; Cyclopropane ring opening
1. Introduction
unwanted complication in a synthetic scheme. As part
of a goal to make the homo-Michael addition reactions
more general, an investigation into the ring opening of
cyclopropylcarbene-chromium complexes was initiated
[4]. In theory, since carbene complexes stabilize adjacent
carbanions better than two ester groups [5], the cyclo-
propylcarbene complex will be as activated as a
cyclopropane 1,1-dioic ester derivative. Successful reali-
zation of this reaction can eliminate the steps often re-
quired to remove the extra electron-withdrawing
group, and can provide additional reaction possibilities
due to the wide variety of reactions unique to Fischer
carbene complexes [6]. These studies will emphasize
the ring opening reactions of cyclopropyl thiocarbene
complexes. The greater acidity of this class of com-
pounds compared to alkoxycarbene complexes [7]
coupled with the greater synthetic utility of vinyl sulfides
compared to enol ethers [8] offers potentially powerful
improvements for the homo-Michael reaction.
Cyclopropane ring opening reactions have proven to
be very valuable tool in synthetic organic chemistry [1].
Electron-deficient cyclopropanes are susceptible to ring
opening by nucleophiles (i.e., the homo-Michael reac-
tion, Scheme 1) [2] and by electrophilic activation fol-
lowed by reaction with a nucleophile [3]. The existence
of numerous routes for the preparation of stereochemi-
cally pure cyclopropanes, coupled with the often stereo-
selective processes by which they undergo ring opening,
provides a potentially powerful method for asymmetric
organic synthesis. Unfortunately, the nucleophilic ring
opening of cyclopropylketones/esters is often restricted
to systems that have two electron groups on one of
the cyclopropane ring carbons. The presence of the sec-
ond electron withdrawing group can present an
*
This manuscript expands upon a previous communi-
cation [9]. Herein is a full experimental plus complete
Corresponding author. Fax: +1 5056462649.
E-mail address: jherndon@nmsu.edu (J.W. Herndon).
0022-328X/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.07.044

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M.D. Reid et al. / Journal of Organometallic Chemistry 690 (2005) 5759–5776
is replacement of oxygen with either nitrogen or
sulfur. Aminocarbene complexes are generally more
stable than alkoxycarbene complexes and less likely
to provide CO-insertion products [13]. Thiocarbene
complexes are generally equal or slightly more reactive
than alkoxycarbene complexes [14], and ultimately will
afford alkenyl sulfides, a useful group for organic
synthesis [8]. Since thiocarbene complexes offer a more
favorable reactivity profile, synthesis of cyclopro-
pyl(thiocarbene) complexes and subsequent examina-
tion of their reaction with alkynes were the initial
research objectives.
Scheme 1.
Attempts to prepare thiophenylcarbene complex 4g
(Scheme 3) proved challenging. Use of the acetoxycar-
bene complex method [15] for the preparation of this
thiocarbene complex was not successful. This reaction
produced numerous products, however prominent peaks
suggestive of a terminal alkyne could be observed in the
crude proton NMR and IR spectra. The crude reaction
mixture was treated with dicobalt octacarbonyl to
retrieve the terminal alkyne, which was assigned the
structure 3. Attempted synthesis of phenylcyclopropyl-
carbene complex 4h resulted in the alkyne ester 5. The
reaction was successful for the formation of simple
cyclopropylcarbene complex 4a, however extended reac-
tion times led to the formation of minor amounts of
chloro-vinyl sulfide derivative 6. The mechanism de-
picted in Scheme 4 can account for the formation of
compounds 2 and 5, and was unique to complexes that
feature carbocation stabilizing groups on the cyclopro-
pane ring. It cannot be ascertained whether the X group
of intermediates 8–10 are acetoxy or thiophenyl groups.
In the absence of these groups simple carbene complex
substitution was observed. The reaction was similarly
successful for the formation of aminocarbene complex
7. Use of the more nucleophilic amine species resulted
in formation of the desired product, likely because cap-
ture of the intermediate acetoxycarbene complex 8g,h
was more efficient.
details (successes and failures) on our investigation of
ring opening reactions of cyclopropylcarbene com-
plexes, primarily using iodine to effect the ring opening
process. Since the appearance of the preliminary com-
munication, several investigators have reported iodine
oxidation of Fischer carbene complexes. Examples
include: (1) the iodine oxidation chemistry of dihetero-
atom-stabilized carbene complexes [10], (2) a procedure
for the conversion of hydrazinocarbene complexes to the
corresponding amides using iodine generated in situ
from sodium perborate [11], and (3) the oxidation of
carbene complex derived anions with iodine in metha-
nol, which afforded CO inserted products [12].
2. Original investigational objectives and preliminary
experiments
In all honesty our investigation of ring opening
reactions of cyclopropyl thiocarbene complexes should
be regarded as an accidental discovery. The original
objective was to study two new processes developed
in our laboratory: (1) coupling of cyclopropylcar-
bene-Group VI metal carbene complexes with alkynes
to produce either cyclopentenones or cycloheptadie-
nones (Scheme 2, Reaction A) and (2) thermal ring
expansion of alkenylcyclopropylcarbene complexes
(Scheme 2, Reaction B). An important variable to test
The results in Scheme 3 suggest that either cyclopropyl
thiocarbene complexes or cyclopropyl acetoxycarbene
Scheme 2.

M.D. Reid et al. / Journal of Organometallic Chemistry 690 (2005) 5759–5776
5761
Scheme 3.
Scheme 4.
complexes are susceptible to ring opening. Based on the
unexpected results in Scheme 3, a program to examine
nucleophilic ring opening of cyclopropyl thiocarbene
complexes was thus initiated.
have been reported for the tributyltin hydride reduc-
tion of dibromocyclopropanes [17], the separation
processes were far simpler if zinc and acetic acid were
used in the reduction step. In most cases, the eventual
carbene complexes were obtained as a single isomer.
The chemical shift of the carbene carbon was very ste-
reochemistry dependent. As noted in Table 1, if there
is an alkyl substituent cis to the carbene carbon, the
chemical shift was typically greater than d 370. In
all of the cases lacking this feature, the chemical shift
was less than d 360.
3. Synthesis of cyclopropyl thiocarbene complexes
A variety of cyclopropyl thiocarbene complexes
were prepared according to the general synthetic route
depicted in Scheme 5 [16]. Although superior yields

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M.D. Reid et al. / Journal of Organometallic Chemistry 690 (2005) 5759–5776
Scheme 5.
Table 1
monium iodide led to alkyne sulfide 14 in nearly quanti-
tative yield. Reaction with sodium azide led to a mixture
of the isocyanide complex 19, bis(thiophenyl)derivative
20 and alkyne 14. No other nucleophile afforded a cyclo-
propane ring opening product. Nucleophiles tested
include bromide, cyanide, thiophenol anion, the potas-
sium salt of ethyl acetoacetate, and trimethyl phosphite.
All of these reactants induced decomposition of the
carbene complex and afforded no identifiable products
other than low yields of the carbene oxidation product
18. Iodide ion was reactive only to the unsubstituted
carbene complex 4a. No reaction was observed with
any of the cyclopropane-substituted analogs 4b–f. No
reaction was observed upon treatment of complex 4a
with tetrabutylammonium bromide.
Next the coupling of the carbene complex 4a with
strong acids and Lewis acids that have nucleophilic
counterions was tested (Scheme 7). Reaction with HBr
in propionic acid afforded the ring opened product 26a
as a mixture of stereoisomers. The reaction with iodotri-
methylsilane equivalents proved to be quite intriguing
[18], and provided different products depending upon
the source of iodide ion. Coupling with chlorotrimeth-
ylsilane and tetrabutylammonium iodide afforded
compound 26b [19], while use of sodium iodide led to
diiodo derivative 27a [3b]. The reaction leading to 27a
appears to be a general process. Treatment of either of
the substrates 4c or 4d with sodium iodide/chlorotri-
methylsilane led to the analogous products 27c/d in
comparable yield. In each case the reaction provided a
single diastereomer with respect to the ring substituents
but an E/Z mixture of trisubstituted alkenes; major
stereoisomer is the one pictured. The method of stereo-
chemical assignment will be discussed in a subsequent
session.
Chemical shifts of various carbene complexes
Carbene complex
d carbene C
360.0
354.1
353.8
372.2
373.1
372.6
356.3
The mechanism depicted in Scheme 8 can account for
the formation of compounds 26a and 26b. Although
bromide ion was ineffective at promoting cyclopropane
ring opening, HBr was quite effective. This suggests that
the presence of acid is somehow activating the ring
opening process. A plausible mechanism involves
protonation of the carbene complex followed by attack
of bromide on the activated complex 28. The reaction
products are the net result of adding H and X to chro-
mium and the carbon–X of the cyclopropane ring
respectively. Apparently the combination of tetrabutyl-
ammonium iodide/chlorotrimethylsilane generates a
sufficient quantity of HI to afford the products of HI
4. Reaction of cyclopropylcarbene complexes with
nucleophiles and pseudohalogens
In the first phase of these studies, cyclopropyl
thiocarbene complex 4a was subjected to reaction with
a variety of nucleophiles (Scheme 6). In two cases, cyclo-
propane ring opening products were observed. Coupling
of cyclopropylcarbene complex 4a with tetrabutylam-

M.D. Reid et al. / Journal of Organometallic Chemistry 690 (2005) 5759–5776
5763
Scheme 6.
The mechanism leading to the diiodo compounds 27
is difficult to explain. Although the combination of
sodium iodide and chlorotrimethylsilane in acetonitrile
is a well-documented alternative to iodotrimethylsilane
[19], there is some debate as to whether this combination
of reagents actually generates iodotrimethylsilane [21].
The mixing of sodium iodide and chlorotrimethylsilane
in dichloromethane generates dark colors suggestive of
the presence of iodine. The optimal yields of 27a were
obtained using a threefold excess of sodium iodide/
chlorotrimethylsilane. Use of only one equivalent of this
reagent resulted in diiodo derivative 27a in low yield.
Based on this observation, the coupling of cyclopropyl-
carbene complex 4a with iodine itself was examined.
This reaction afforded a 97:3 E/Z mixture of 27a in
excellent yield using only a slight excess of iodine. The
major isomer (Z) is the one depicted. The mechanism
for the formation of 27a is depicted in Scheme 9. Activa-
tion of the carbene complex by iodine followed by CO
dissociation and attack of the resulting iodide at the
cyclopropane carbon followed by reductive elimination
has been proposed. The CO dissociation step is an
essential mechanistic feature revealed during attempted
geometry optimization of intermediate carbene complex
36. This is also consistent with other studies where a
pentacarbonyl analog of intermediate 34a afforded only
CO-inserted products [12]. An alternative mechanism
that cannot be ruled out is formation of diiodide
derivative 33a followed by rearrangement [22]. Further
support for the mechanism employing intermediate
Scheme 7.
addition. Under no conditions could the expected
vinylsilane product 30 be isolated. The addition of
HBr to methylcarbene complex 31 had already been
reported [20], however no mechanism was proposed.

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M.D. Reid et al. / Journal of Organometallic Chemistry 690 (2005) 5759–5776
Scheme 8.
Scheme 9.
34a is the recently reported formation of stable seven-
coordinate Group VI metal carbene complexes in the
+2 oxidation state through treatment of Fischer carbene
complexes with halogens or tin(IV) halides [23].
The reaction of complex 4a with other halogens and
pseudohalogens was tested (Table 2). A similar reaction
was observed using bromine (Entry B). Phenylselenenyl
chloride afforded a mixture of the selenide 40 (X = Cl,
Y = SePh) and the dichloride compound 41 (X,
Y = Cl) (Entry C). Attempted reaction with iodine azide
afforded only the diiodo derivative 27a in low yield. A
variety of more highly substituted cyclopropylcarbene
complexes were tested in their reaction with iodine and
the reaction was found to be general (Entries D–J).
Reaction with unsymmetrical cyclopropylcarbene
complexes led preferentially to compounds where iodide
attacks the more substituted carbon of the cyclopropane
ring (Entries G–J). In nearly all cases, the reaction affor-
ded mostly the Z isomer. The double bond stereochem-
istry appears to be established under conditions of
kinetic control. The same compound (27f) produced
from two different substrates affords different ratios of
double bond isomers (Entries I and J). Since the more
substituted iodide was preferentially obtained in unsym-

M.D. Reid et al. / Journal of Organometallic Chemistry 690 (2005) 5759–5776
5765
Table 2
Reaction of cyclopropylcarbene complexes with halogens and pseudohalogens
Entry
R1
R2
R3
Y–X
Yield 27, 39–42
Z/E 27
Yield 38
A
B
C
H
H
H
H
H
H
H
H
H
I2
Br2
PhSe–Cl
88% (27a)
61% (39)
46% (40)
97:3
93:7
50:50
30% (X, Y = Cl) (41)
85% (27b)
82% (27c)
Da
Ea
F
H
H
H
R2, R3 = –(CH2)4
I2
I2
I2
72:28
93:7
75:25
R2, R3 = –(CH2)6 cis ring fusion
R2, R3 = –(CH2)4 trans ring
fusion
71% (27d)
Gb
H
I
Me
Me
H
Me
Me
H
H
H
H
I2
Br2
I2
19:81
20:80
17:83
84:16
22% (42)
68% (27f)
54% (27f)
n-C6H13 cis isomer
n-C6H13 trans isomer
3% (38f)
22% (38f)
J
H
I2
a
The starting carbene complex was exclusively the exo isomer.
The product was unstable and rearranged to the allylic iodide.
b
metrical substrates (Entries G–J), this implies that there
is substantial positive charge character at the cyclopro-
pane carbons in intermediates 34.
strate was chosen for this study since there is a signifi-
cant amount of the minor isomer. In this case, a
mixture of alkenes (43) was obtained which could easily
be assigned through their coupling constants (the major
isomer is structure 43 depicted in Scheme 10); the major
isomer from halogen replacement is trans, thus suggest-
ing that the major isomer in the starting compound 27b
is Z [24]. In diiodide 27b, the chemical shift of HC differs
by 0.55 ppm, and the higher chemical shift is observed in
the minor stereoisomer. This chemical shift difference is
consistent throughout all of the products in Table 2, and
has been used to assign the double bond configuration
of all of the diiodide products (i.e., the isomer where
the alkene proton has the higher chemical shift has been
assigned as the E isomer).
5. Assignment and rationalization of stereochemistry
The stereochemistry of the ring opening process was
established by analysis of the coupling constants for
the iodine-bearing carbon atom in compound 27b
(Scheme 10). In the cyclohexyl case this proton (HA) ap-
pears as a td with J values of ꢀ11 Hz (t) and ꢀ4 Hz (d),
suggesting that this proton is axial and coupled to two
other axial protons (HB and HE) and an equatorial pro-
ton (HD). A similar pattern was noted in the proton
NMR spectrum of the product 27c derived from cis-
cyclooctyl-fused carbene complex 4c. The alkene stereo-
chemistry was determined through halogen metal
exchange and protonation on compound 27b. This sub-
An attempt to improve the stereochemistry in one of
the less stereoselective systems was initiated through
adjustment of the steric bulk of the sulfur substituent.
Reaction of a variety of cyclohexyl fused cyclopropyl-
Scheme 10.

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M.D. Reid et al. / Journal of Organometallic Chemistry 690 (2005) 5759–5776
carbene complexes with iodine was examined. As noted
in the Table 3, as the steric bulk of the sulfur substituent
increases, the reaction becomes more Z selective. The
highest stereoselectivity was observed in the reaction
employing the 2-methylphenylthiocarbene complex
derivative. For the alkylthiocarbene complexes, slightly
higher stereoselectivity was noted for the isopropylthio-
carbene complex vs. the ethylthiocarbene complex. At-
tempts to prepare the t-butylthiocarbene complex and
the mesitylphenylthiocarbene complex were not
successful.
gests that in intermediate 34a the thiophenyl group ex-
erts a more powerful steric influence versus the
Cr(CO)4I group, thus favoring properly aligned struc-
ture 34a-Z over alternative properly aligned structure
34a-E. Structure 34a-Z eventually leads to the observed
product of the reaction. These preferences are appar-
ently reversed for cases where there is a cis substituent
at the carbon undergoing attack by halide ion (Entries
G–I of Table 2); the E isomer is the major product in
these cases.
Based on these results, the model depicted in Scheme
11 has been proposed to rationalize the stereoselectivity.
The essential features of the model are: (1) the s-cis con-
formation is predominant at equilibrium and (2) overlap
of the C–C bond that is broken and the p-orbital at the
carbene carbon is essential for the bond breaking step.
The methylcarbene analog of 4a (complex 47 in Scheme
12) exists as the s-cis conformation in the solid state [25]
and cyclopropylcarbene complex 4a also minimizes in
this conformation. The observed stereochemistry sug-
6. Iodine oxidation of other carbene complexes
The iodine oxidation reaction was also attempted on
related carbene complexes. The alkoxycarbene complex
analog 44 (Scheme 12) was not reactive to iodide ion,
however, iodoester derivative 46 was obtained upon
treatment with iodine. This reaction likely proceeds
through enol ether derivative 45, which should be highly
susceptible to hydrolysis [26]. The methylcarbene com-
Table 3
Stereoselectivity of various cyclopropyl thiocarbene complexes reacting with iodine
R
Z/E
Ph (b series)
72:28
91:9
69:31
51:49
58:42
2-Methylphenyl (i series)
3-Methylphenyl (j series)
Ethyl (k series)
Isopropyl (l series)
Scheme 11.

M.D. Reid et al. / Journal of Organometallic Chemistry 690 (2005) 5759–5776
5767
Scheme 12.
plex 47 led to the iodo-alkene 48 in moderate yield. The
carbene dimer 50 was observed upon treatment of the
phenylcarbene complex 49 with iodine [27].
molecules. In most cases, the reaction proceeds with a
high degree of stereoselectivity. A mechanism has been
proposed that involves initial electrophilic activation at
chromium followed by nucleophilic ring opening of the
activated cyclopropane derivative. The diiodide prod-
ucts undergo selective palladium-catalyzed coupling
reactions at the alkenyl iodide functionality.
7. Palladium-catalyzed coupling reactions
Palladium-catalyzed alkynylation reactions were
examined for diiodide 27a (Scheme 13). Under the stan-
dard conditions for the Sonogashira coupling [28], the
dienyne derivative 51 was obtained in high yield. In
the highly basic solvent system employed elimination
accompanies the Sonogashira coupling. The Stille alky-
nylation [29], which employs a less basic solvent system,
led exclusively to the conjugated enyne-iodide 52 in
moderate yield.
9. Experimental [30]
Starting materials. Cyclopropyl bromide, chromium
hexacarbonyl, and all of the thiol derivatives employed
in this investigation are commercially available. All of
the monobromocyclopropane derivatives were prepared
through a sequence involving addition of dibromocar-
bene to an alkene followed by monodehalogenation
using zinc in acetic acid [16]. Dibromocarbene addition
to cyclohexene afforded 7,7-dibromobicyclo[4.1.0]hep-
tane [31]. Dibromocarbene addition to cis cyclooctene
afforded cis-9,9-dibromobicyclo[6.1.0]nonane [32]. Dib-
romocarbene addition to trans-cyclooctene afforded
trans-9,9-dibromobicyclo[6.1.0]nonane [33]. Dibromo-
8. Summary
In summary, cyclopropyl thiocarbene complexes un-
dergo a variety of ring opening reactions resulting in
the efficient preparation of highly functionalized organic
Scheme 13.

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M.D. Reid et al. / Journal of Organometallic Chemistry 690 (2005) 5759–5776
carbene addition to isobutylene afforded 1,1-dibromo-
2,2-dimethylcyclopropane [34]. Dibromocarbene
addition to 1-octene afforded 1-(2,2-dibromocyclopro-
pyl)hexane [35].
130.5, 129.8, 42.5, 22.7; IR (CH2Cl2): 2053 (s), 1948
(vs) cmÀ1; Mass Spec (EI): 354 (M+, 1), 326 (59), 270
(66), 218 (30), 186 (10), 162 (60), 110 (100); HRMS;
calcd for C15H10CrO5S 353.9654, found 353.9652. 4-
chloro-1-thiophenyl-1-butene (6): 1H NMR (CDCl3):
major isomer: d 6.19 (d, 1H, J = 14.9 Hz); minor isomer:
d 6.25 (d, 1H, J = 13.0 Hz); the following peaks are
overlapping in both isomers: d 7.21 (m, 5H), 3.55 (m,
2H), 2.64 (m, 2H). Integration of the alkene protons re-
veals that this compound is a 60:40 E:Z mixture.
General procedure 1 – Conversion of monobromocyclo-
propanes to the corresponding acylate salts. To a solution
of monobromocyclopropane (10 mmol) in anhydrous
ether (25 mL) at À78 °C under nitrogen was added t-
butyllithium (20 mmol of a 1.7 M hexane solution)
dropwise over a 10 min period. This solution was stirred
for 20 min at À78 °C, and then transferred via cannula
to a suspension of chromium hexacarbonyl (10 mmol) in
ether (50 mL) at 0 °C. The reaction was warmed to 25
°C and stirred for 1 h. The solvent was removed on a ro-
tary evaporator and the residue dissolved in a minimum
amount of water, then filtered through Celite. To the fil-
trate a saturated aqueous solution of tetramethylammo-
nium bromide (20 mL) was added. The resulting
precipitate was collected by suction filtration, then dis-
solved in dichloromethane and dried over sodium sul-
fate. The solvent was removed on a rotary evaporator
to afford the acylate salt, which was used without further
purification. In some cases, the NMR spectrum could
not be acquired, likely due to the presence of paramag-
netic impurities.
Preparation of the cyclohexyl fused carbene complex
4b. General procedure 1 was followed using 7-bromobi-
cyclo[4.1.0]heptane (1.000 g, 5.70 mmol), t-butyllithium
(6.72 mL, 11.4 mmol of a 1.7 M hexane solution), and
chromium hexacarbonyl (1.257 g, 5.70 mmol). A yellow
solid (1.394 g, 54% yield) identified as acylate salt 1b was
obtained. Acylate salt 1b: IR (CH2Cl2): 2030 (sh), 1981
(sh), 1896 (vs) cmÀ1. General procedure 2 was followed
using thiophenol (0.110 mL, 1.03 mmol), acylate salt 1b
(0.400 g, 1.03 mmol), and acetyl chloride (0.070 mL,
1.03 mmol). A red-orange solid identified as carbene
complex 4b (0.156 g, 35% yield) was obtained. Carbene
1
complex 4b: H NMR (CDCl3): d 7.45–7.32 (m, 5H),
2.69 (br s, 3H), 1.98–1.93 (m, 2H), 1.48 (m, 2H), 1.23–
1.15 (m, 2H), 0.83–0.80 (m, 2H); 13C NMR (CDCl3): d
354.1, 225.5, 216.9, 136.3, 132.6, 130.4, 129.5, 58.7,
39.9, 23.5, 20.6; IR (CH2Cl2): 2056 (s), 1975 (s), 1938
(vs) cmÀ1; Mass Spec (EI): 408 (M+, 1), 380 (31), 324
(34), 242 (9), 216 (48), 186 (23), 134 (24), 123 (35), 110
(100); HRMS: calcd for C19H16CrO5S 408.0124, found
408.0148.
General procedure 2 – Conversion of cyclopropylcar-
bene acylates to the corresponding thiocarbene complexes.
To a solution of the crude acylate salt (1.0 mmol) in
dichloromethane (25 mL) at 0 °C under nitrogen was
added via syringe a solution of acetyl chloride (1.0 mmol)
in dichloromethane (2 mL), followed immediately by
addition of a solution of thiophenol (1.0 mmol) in dichlo-
romethane. The reaction mixture was stirred at 0 °C for a
30 min period. Evaporation of the solvent followed by
flash chromatography on silica gel using pure hexane
as the eluent afforded the pure thiocarbene complex.
Preparation of cyclopropylcarbene complex 4a. Gen-
eral procedure 1 was followed using cyclopropyl bro-
mide (1.200 g, 10.0 mmol), t-butyllithium (11.8 mL,
20.0 mmol of a 1.7 M hexane solution), and chromium
hexacarbonyl (2.200 g, 10.0 mmol). A yellow solid
(2.010 g, 60% yield) identified as acylate salt 1a was ob-
tained. Acylate salt 1a. 1H NMR (acetone-d6): d 3.44 (s,
12H), 2.76 (m, 1H), 0.65 (m, 2H), 0.27 (m, 2H). The
spectral data are consistent with that previously re-
ported for this compound [36]. General procedure 2
was followed using thiophenol (0.150 mL, 1.49 mmol),
acylate salt 1a (0.500 g, 1.49 mmol), and acetyl chloride
(0.110 mL, 1.49 mmol). A red oil identified as carbene
complex 4a (0.433 g, 82% yield) was obtained. A minor
product (<10% yield) tentatively identified as 4-chloro-
1-thiophenyl-1-butene (6) was observed when the reac-
tion was allowed to proceed for a long time. Carbene
Preparation of the cis-cyclooctyl-fused carbene
complex 4c. General procedure 1 was followed using
cis-9-bromobicyclo[6.1.0]nonane (1.179 g, 5.80 mmol),
t-butyllithium (6.8 mL, 11.6 mmol of a 1.7 M hexane
solution), and chromium hexacarbonyl (1.278 g, 5.80
mmol). A yellow oil (1.518 g, 63% yield) identified as
1
acylate salt 1c was obtained. Acylate salt 1c. H NMR
(acetone-d6): d 3.40 (s, 12H), 2.95 (t, 1H, J = 5.0 Hz),
1.90 (m, 2H), 1.33 (m, 12H); IR (CH2Cl2): 2055 (s),
1980 (vs) cmÀ1. General procedure 2 was followed using
thiophenol (0.050 mL, 0.51 mmol), acylate salt 1c (0.213
g, 0.51 mmol), and acetyl chloride (0.040 mL, 0.50
mmol). A red solid identified as carbene complex 4c
(0.134 g, 60% yield) was obtained. Carbene complex
1
4c. H NMR (CDCl3): d 7.45–7.20 (m, 5H), 2.42–2.40
(m, 2H), 2.32 (t, 1H, J = 3.9 Hz), 1.96–1.87 (d of m,
2H, J = 13.9 Hz), 1.57–1.18 (m, 8H), 0.93–0.81 (m,
2H); 13C NMR (CDCl3): d 353.8, 225.7, 217.0, 136.3,
132.6, 130.4, 129.5, 59.4, 44.4, 29.1, 26.3; IR (CH2Cl2):
2054 (s), 1976 (vs), 1904 (s) cmÀ1; Mass Spec (EI): 408
(M+ À CO, 31), 352 (46), 324 (5), 296 (15), 270 (32),
244 (95), 218 (100), 186 (27), 151 (90), 135 (74); HRMS:
calcd for C20H20CrO4S 408.0487, found 408.0493.
Preparation of the trans-cyclooctyl fused carbene
complex 4d. General procedure 1 was followed using
1
complex 4a: H NMR (CDCl3): d 7.41 (m, 5H), 2.78
(tt, 1H, J = 7.8, 4.3 Hz), 1.96 (m, 2 H), 1.58 (m, 2H);
13C NMR (CDCl3): d 360.0, 226.0, 216.6, 136.4, 132.1,

M.D. Reid et al. / Journal of Organometallic Chemistry 690 (2005) 5759–5776
5769
trans-9-bromobicyclo[6.1.0]nonane (1.304 g, 6.43
mmol), t-butyllithium (7.6 mL, 12.9 mmol of a 1.7 M
hexane solution), and chromium hexacarbonyl (1.414
g, 6.43 mmol). A green oil (1.142 g, 43% yield) identified
as acylate salt 1d was obtained. Acylate salt 1d: IR
(CH2Cl2): 2055 (s), 1975 (vs), 1902 (s) cmÀ1. General
procedure 2 was followed using thiophenol (0.280 mL,
2.73 mmol), acylate salt 1d (1.140 g, 2.73 mmol), and
acetyl chloride (0.200 mL, 2.73 mmol). A red solid iden-
tified as carbene complex 4d (0.650 g, 55% yield) was
(m, 5H), 3.00 (br s, 1H), 1.85 (m, 1H), 1.70–1.45 (m,
4H), 1.42–1.08 (m, 8H), 0.85 (m, 3H); 13C NMR
(CDCl3): d 372.6, 227.6, 216.4, 134.5, 132.1, 130.4,
129.6, 48.7, 38.7, 31.7, 29.7, 29.5, 28.8, 22.6, 14.0; IR
(CH2Cl2): 2056 (s), 1938 (vs) cmÀ1; Mass Spec (EI):
410 (M À CO, 1); 354 (5), 247 (70), 218 (41), 207 (27),
175 (33), 147 (28), 134 (47), 108 (100); HRMS: calcd
for C20H22CrO4S 410.0644, found 410.0648. Carbene
1
complex 4f-trans: H NMR (CDCl3): d 7.47–7.24 (m,
5H), 2.63 (dt, 1H, J = 8.0, 4.0 Hz), 2.33 (m, 1H), 2.29
(td, 1H, J = 8.0, 4.0 Hz); 1.59–1.51 (m, 2H), 1.25–1.21
(m, 9H), 0.83 (t, 3H, J = 7.0 Hz); Irradiate at 2.30: pat-
terns altered at d 2.63 and 1.59–1.51; 13C NMR (CDCl3):
d 356.3, 225.5, 216.8, 134.5, 132.4, 130.5, 129.7, 51.9,
39.6, 33.4, 31.7, 31.6, 28.8, 28.4, 22.5, 14.0; IR (CH2Cl2):
2068 (s), 2056 (s), 1987 (s) 1938 (vs) cmÀ1; Mass Spec
(CI): 410 (M À CO, 7); 354 (20), 274 (25); HRMS: calcd
for C20H22CrO4S 410.0644, found 410.0649.
1
obtained. Carbene complex 4d: H NMR (CDCl3): d
7.45–7.20 (m, 5H), 2.70 (br s, 1H), 2.19 (d of m, 1H,
J = 16 Hz), 2.05–1.62 (m, 6H), 1.55–0.95 (m, 6H), 0.79
(qd, 1H, J = 10.5, 5.0 Hz); 13C NMR (CDCl3): d
372.2, 222.7, 216.5, 134.5, 131.8, 130.3, 129.6, 53.5,
43.2, 39.0, 33.5, 31.9, 31.4, 29.7, 28.6, 28.1; IR (CH2Cl2):
2055 (s), 1941 (vs) cmÀ1; Mass Spec (EI): 408
(M+ À CO, 6), 352 (14), 270 (29), 244 (65), 220 (56),
151 (100), 135 (39), 117 (34); HRMS: calcd for
C20H20CrO4S 408.0487, found 408.0471.
Preparation of the 2-methyl-2-vinylcyclopropylcarbene
acylate (1g). General procedure 1 was followed using 1-
bromo-2-methyl-2-ethenylcyclopropane (1.000 g, 6.20
mmol), t-butyllithium (7.40 mL, 12.4 mmol of a 1.7 M
hexane solution), and chromium hexacarbonyl (1.368
g, 6.20 mmol). A yellow solid (1.628 g, 70% yield) iden-
tified as acylate salt 1g was obtained. Acylate salt 1g. 1H
NMR (acetone-d6): major isomer d 5.75 (dd, 1H,
J = 17.6, 10.8 Hz), 1.26 (s, 3H),; minor isomer: d 5.54
(dd, 1H, J = 17.2, 10.5 Hz); the following peaks are
overlapping in both isomers: d 4.81 (m, 2 H), 3.45 (s,
12H), 3.00 (m, 1H), 1.31 (m, 1H), 0.42 (m, 1H); IR
Preparation of the 2,2-dimethylcyclopropylcarbene
complex 4e. General procedure 1 was followed using 2-
bromo-1,1-dimethylcyclopropane (1.000 g, 4.88 mmol),
t-butyllithium (5.74 mL, 13.4 mmol of a 1.7 M hexane
solution), and chromium hexacarbonyl (1.477 g, 6.70
mmol). A greenish-yellow oil (1.606 g, 66% yield) iden-
tified as acylate salt 1e was obtained. IR (CH2Cl2):
2056 (s), 1974 (vs), 1906 (s) cmÀ1. General procedure 2
was followed using thiophenol (0.140 mL, 1.38 mmol),
acylate salt 1e (0.500 g, 1.38 mmol), and acetyl chloride
(0.100 mL, 1.38 mmol). A red solid identified as carbene
complex 4e (0.266 g, 51% yield) was obtained. Carbene
(CH2Cl2): 2030 (sh), 1981 (sh), 1895 (vs) cmÀ1
.
Coupling of acylate salt 1g with acetyl chloride and thi-
ophenol. General procedure 2 was followed using thi-
ophenol (0.140 mL, 1.38 mmol), acylate salt 1g (0.500
g, 1.38 mmol), and acetyl chloride (0.100 mL, 1.38
mmol). A yellowish oil identified as enyne 2 (0.067 g,
25% yield) was obtained. Even after chromatography
this compound is highly impure. In subsequent experi-
ments, the crude mixture was treated with dicobalt octa-
carbonyl as outlined below. Alkyne 2. 1H NMR
(CDCl3): d 7.21 (m, 5H). 5.33 (tq, 1H, J = 7.8, 1.0
Hz), 3.48 (d, 2H, J = 7.8 Hz), 2.77 (d, 2H, J = 2.7
Hz), 1.90 (t, 1H, J = 2.7 Hz), 1.76 (d, 3H, J = 1.0 Hz);
1
complex 4e: H NMR (CDCl3): d 7.45–7.20 (m, 5H);
2.69 (br s, 1H); 1.94 (br t, 1H, J = 5.9 Hz); 1.51 (br t,
1H, J = 5.8 Hz), 1.01 (s, 3H), 0.61 (br s, 3H); 13C
NMR (CDCl3): d 373.1, 227.7, 216.4, 138.0, 132.1,
130.4, 129.6, 56.3, 34.0, 32.2, 27.5, 20.5; IR (CH2Cl2):
2056 (s), 1944 (vs) cmÀ1; Mass Spec (EI): 382 (M+, 1),
354 (27), 298 (28), 270 (7), 240 (20), 216 (21), 186 (32),
151 (26), 134 (19), 110 (100); HRMS: calcd for
C17H14CrO5S 381.9967, found 382.0001.
Preparation of the 2-hexylcyclopropylcarbene complex
4f. General procedure 1 was followed using 2-bromo-1-
hexylcyclopropane (1.000 g, 4.88 mmol), t-butyllithium
(5.74 mL, 9.76 mmol of a 1.7 M hexane solution), and
chromium hexacarbonyl (1.073 g, 4.88 mmol). A green
oil (0.644 g, 32% yield) identified as acylate salt 1f was
obtained. General procedure 2 was followed using thi-
ophenol (0.070 mL, 0.67 mmol), acylate salt 1f (0.250
g, 0.67 mmol), and acetyl chloride (0.050 mL, 0.67
mmol). Chromatography yielded two fractions, both
red solids. The product in the first fraction was identified
as the cis-carbene complex 4f (0.077 g, 27% yield). The
product in the second fraction was identified as the
trans-carbene complex 4f (0.029 g, 10% yield). Car-
bene complex 4f-cis: 1H NMR (CDCl3): d 7.48–7.20
IR (CH2Cl2): 3305 (s) cmÀ1
.
Conversion of alkyne 2 to the corresponding cobalt
complex 3. The crude product (before chromatography)
from the previous reaction was dissolved in pentane (20
mL) and cooled to 0 °C. To this solution was added so-
lid dicobalt octacarbonyl (0.340 g, 1.20 mmol). The
reaction was stirred for 10 min at 0°C and then for 12
h at 25 °C. The solvent was removed on a rotary evap-
orator and the residue was purified by flash chromatog-
raphy on silica gel using pure hexane as the eluent. A red
oil identified as alkyne-cobalt complex 3 (0.174 g, 30%
yield) was obtained. Alkyne-cobalt complex 3. 1H
NMR (CDCl3): d 7.23 (m, 5H), 5.96 (s, 1H), 5.34 (tq,

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M.D. Reid et al. / Journal of Organometallic Chemistry 690 (2005) 5759–5776
1H, J = 7.8, 0.7), 3.54 (d, 2H, J = 7.8), 3.42 (s, 2H), 1.77
(d, 3H, J = 0.7); 13C NMR (CDCl3): d 199.8, 137.1,
136.2, 130.3, 128.8, 126.4, 122.4, 93.5, 73.5, 36.5, 32.4,
23.5; IR (CH2Cl2): d 2093 (sh), 2053 (s), 2025 (vs)
cmÀ1; MS (CI): 432 (M+ À 2CO, 44.8), 404 (40.1), 376
(9.2), 320 (32.1), 202 (100), 186 (100).
anide complex 19 (0,020 g, 17% yield). The product in
the second fraction was identified as 4-phenylthio-1-
buyne (14) (0.004 g, 5% yield). The product in the third
fraction was identified as 1,4-bis(phenylthio)-1-butene
1
(20) (0.022 g, 17%). Isocyanide complex 19: H NMR
(CDCl3): d 3.20 (m, 1H), 1.10 (m, 4H); IR (CH2Cl2):
2175 (m), 2063 (m), 1950 (vs) cmÀ1. The spectral data
were consistent with those previously reported for this
compound [39]. 1,4-bis(phenylthio)-1-butene (20). 1H
NMR (CDCl3): major (trans) isomer: d 6.27 (d, 1H,
J = 14.9 Hz), 2.58 (q, 2H, J = 7.2 Hz); minor (cis) iso-
mer: d 6.29 (d, 1H, J = 8.2 Hz), 2.58 (q, 2H, J = 7.2
Hz); the following peaks are overlapping in both iso-
mers: d 7.38–7.16 (m, 10H), 5.83 (m, 1H), 3.00 (t, 2H,
J = 7.2 Hz); 13C NMR (CDCl3): d 133.4, 133.0, 130.1,
129.6, 129.5, 129.1, 129.0, 128.9, 128.8, 128.7, 126.4,
126.2, 126.1, 125.2, 123.8, 33.2, 33.0, 32.7, 28.8; Mass
Spec (EI): 272 (M+, 16), 271 (56), 179 (22), 164 (37),
153 (8), 149 (71), 123 (100), 109 (99); HRMS: calcd for
C16H16S2 272.0693, found 272.0683. Integration of the
alkene protons reveals that this compound is a 60:40
E:Z mixture.
General procedure 3 – Reaction of carbene complexes
with electrophiles. The electrophile (1.05 eq) was placed
in a round bottom flask under nitrogen and cooled to
À20 °C. To this solution was added an 0.02M solution
of the carbene complex (1.0 eq) in dichloromethane.
The solution was allowed to slowly warm to 25 °C
and allowed to stir at 25 °C for a specified period of time
depending upon the electrophile (iodine – 4 h, pyridi-
nium bromide perbromide – 12 h, phenylselenenyl
chloride – 24 h). The mixture was filtered through Celite
and the solvent was removed on a rotary evaporator.
The residue was purified by flash chromatography on
silica gel. The eluent was pure hexane unless otherwise
specified.
Preparation of the 2-methyl-2-phenylcyclopropyl-
carbene acylate (1h). General procedure 1 was followed
using 1-bromo-2-methyl-2-phenylcyclopropane (1.000 g,
4.70 mmol), t-butyllithium (5.6 mL, 9.4 mmol of a 1.7 M
hexane solution), and chromium hexacarbonyl (1.043 g,
4.70 mmol). A yellow oil (1.088 g, 54% yield) identified
as acylate salt 1h was obtained. Acylate salt 1h: 1H
NMR (acetone-d6): d 7.40 (m, 5H), 3.35 (s, 13H), 1.7–
0.6 (m, 5H); IR (CH2Cl2): 2030 (sh), 1981 (sh), 1896
(vs) cmÀ1
.
Coupling of acylate salt 1h with acetyl chloride and
thiophenol. General procedure 2 was followed using
thiophenol (0.048 mL, 0.47 mmol), acylate salt 1h
(0.200 g, 0.47 mmol), and acetyl chloride (0.030 mL,
0.47 mmol). In the chromatography 19:1 hexane: ethyl
acetate was used as the eluent. A colorless oil identified
as alkyne-ester 5 (0.065 g, 68% yield) was obtained.
Alkyne-ester 5: 1H NMR (CDCl3): d 7.24 (m, 5H),
3.01 (dd, 1H, J = 16.6, 2.7 Hz), 2.85 (dd, 1H, J = 16.6,
2.7 Hz), 2.10 (s, 3H), 1.93 (t, 1H, J = 2.7 Hz), 1.84 (s,
3H); 13C NMR (CDCl3): d 169.5, 143.4, 128.2, 127.4,
124.5, 81.6, 79.5, 71.0, 32.1, 25.2, 22.0; IR (CH2Cl2):
3300 (m), 1737 (s), 1685 (m) cmÀ1. The spectral data
are consistent with those previously reported for this
compound [37].
Coupling of carbene complex 4a with tetrabutylammo-
nium iodide. To a solution of carbene complex 4a (0.100
g, 0.280 mmol) in dichloromethane (10 mL) at 25 °C
under nitrogen was added a solution of tetrabutylam-
monium iodide (0.313 g, 0.86 mmol) in dichloromethane
(2 mL). This mixture was stirred at 25 °C for 12 h, and
then the solvent was removed on a rotary evaporator.
Flash chromatography of the residue using pure hexane
as the eluent afforded a colorless oil (0.045 g, 99% yield)
identified as 4-phenylthio-1-butyne (14). 4-phenylthio-1-
Reaction of carbene complex 4a with HBr. General
procedure 3 was followed using carbene complex 4a
(0.197 g, 0.590 mmol) and hydrogen bromide (0.12 mL
of a 30% propionic acid solution, 0.590 mmol). Purifica-
tion by flash chromatography afforded two fractions.
The product in the first fraction was identified as start-
ing carbene complex 4a (0.040 g, 11% recovery). The
product in the second fraction was identified as 4-bro-
mo-1-thiophenyl-1-butene (26a) (0.087 g, 40% yield).
4-bromo-1-thiophenyl-1-butene (26a): 1H NMR
1
butyne (14): H NMR (CDCl3): d 7.24 (m, 5H), 3.00
(t, 2H, J = 7.5 Hz), 2.41 (td, 2H, J = 7.5, 2.6 Hz), 1.97
(t, 1H, J = 2.6 Hz); IR (CH2Cl2): 3305 (s) cmÀ1. The
spectral data were consistent with those previously
reported for this compound [38].
Coupling of carbene complex 4a with sodium azide. To
a solution of carbene complex 4a (0.178 g, 0.480 mmol)
in 5:1 t-butyl alcohol: water (6 mL) at 25 °C under nitro-
gen was added a solution of sodium azide (0.037 g, 0.580
mmol) in water (1 mL). The deep red color of the car-
bene complex immediately turned yellow and eventually
colorless after 1 h. Extraction of the crude mixture with
dichloromethane followed by flash chromatography
using hexane as the eluent afforded three fractions.
The product in the first fraction was identified as isocy-
(CDCl3): major isomer (trans): d 6.22 (dt, 1H,
J = 15.0, 1.4 Hz), 3.35 (t, 2H, J = 6.9 Hz), 2.58 (qd,
2H, J = 6.9, 1.4 Hz); minor isomer (cis): d 6.30 (dt,
1H, J = 9.3, 1.2 Hz), 3.38 (t, 2H, J = 6.9 Hz), 2.68
(qd, 2H, J = 6.9, 1.2 Hz); the following peaks are over-
lapping in both isomers: d 7.30–7.15 (m, 5H), 5.82–5.67
(m, 1H); 13C NMR (CDCl3): d 130.9, 129.4, 129.2,
129.1, 128.7, 126.6, 126.6, 126.4, 125.5, 36.2, 32.2,
31.6; Mass Spec (EI): 244 (M+2, 50), 242 (M, 50), 163
(44), 149 (100), 135 (36), 116 (64), 109 (73); HRMS:

M.D. Reid et al. / Journal of Organometallic Chemistry 690 (2005) 5759–5776
5771
calcd for C10H11BrS 241.9764, found 241.9803. Integra-
tion of the alkene protons reveals that this compound is
a 60:40 E:Z mixture.
27c (0.019 g, 65% yield). Diiodide 27c: 1H NMR
(CDCl3): major (Z) isomer: d 6.15 (d, 1H, J = 9.3 Hz),
3.15 (m, 1H); minor (E) isomer: d 6.65 (d, 1H, J = 9.8
Hz), 3.55 (m, 1H); the following peaks are overlapping
in both isomers: d 7.38–7.19 (m, 5H), 4.37 (dt, 1H,
J = 11.2, 4.2 Hz); 2.22–2.10 (m, 2H), 1.71–1.43 (m,
10H); Irradiate at d 3.15: d 6.15 (s), 4.38 (t), 13C NMR
(CDCl3) d 153.1, 135.4, 130.5, 129.1, 127.4, 91.3, 55.2,
41.6, 35.3, 31.8, 27.7, 26.6, 26.2, 25.7; Mass Spec (CI):
498 (M, 27), 371 (100), 275 (92), 244 (38), 147 (86),
127 (43), 110 (27); HRMS: calcd for C16H20I2S
497.9375, found 497.9386. Integration of the alkene
peaks revealed that this is a 83:17 Z:E mixture.
Reaction of carbene complex 4d with sodium iodide/
chlorotrimethylsilane. General procedure 4 was followed
using carbene complex 4d (0.069 g, 0.16 mmol), chloro-
trimethylsilane (0.051 g, 0.47 mmol) and sodium iodide
(0.071 g, 0.47 mmol). Chromatographic purification
afforded a colorless compound identified as diiodide
27d (0.033 g, 42% yield). Diiodide 27d: 1H NMR
(CDCl3): major (Z) isomer: d 6.09 (d, 1H, J = 8.8 Hz),
2.47 (m, 1H); minor (E) isomer: d 6.69 (d, 1H, J = 8.0
Hz), 2.85 (m, 1H); the following peaks are overlapping
in both isomers: d 7.34–7.15 (m, 5H), 4.48 (m, 1H),
2.32–2.23 (m, 2H), 1.86–1.69 (m, 4H), 1.46–1.21 (m,
4H); 13C NMR (CDCl3): d 158.5, 152.2, 136.8, 136.0,
31.2, 29.8, 29.7, 26.9, 25.7, 25.5; Mass Spec (EI): 498
(M+, 9), 371 (100), 243 (39), 218 (65), 147 (53), 133
(65), 123 (46); HRMS: calcd for C16H20I2S 497.9375,
found 497.9384. Integration of the alkene peaks revealed
that this is a 71:29 Z:E mixture.
Reaction of carbene complex 4a with tetrabutylammo-
nium iodide/chlorotrimethylsilane. To a solution of
carbene complex 4a (0.092 g, 0.26 mmol) in dichloro-
methane (10 mL) at 0 °C under nitrogen was added a
solution of tetrabutylammonium iodide (0.134 g, 0.31
mmol) and chlorotrimethylsilane (0.115 g, 0.39 mmol)
in dichloromethane (5 mL). The reaction mixture was
stirred at 0 °C for 12 h. After removal of the solvent
on a rotary evaporator, the reside was purified by flash
chromatography on silica gel using pure hexane as the
eluent. A slightly yellow oil identified as trans-4-iodo-
1-thiophenyl-1-butene (26b) was obtained (0.071 g,
93% yield). trans-4-Iodo-1-thiophenyl-1-butene (26b):
1H NMR (CDCl3): d 7.38–7.20 (m, 5H), 6.25 (dt, 1H,
J = 15.0, 1.2 Hz), 5.80 (dt, 1H, J = 15.0, 7.1 Hz), 3.18
(t, 2H, J = 7.1 Hz), 2.70 (qd, 2H, J = 7.1, 1.2 Hz); 13C
NMR (CDCl3): d 135.3, 132.5, 129.4, 129.0, 126.6,
126.2, 36.9, 4.3; Mass Spec (EI): 290 (M+, 41), 289
(74), 163 (100), 128 (30), 109 (50), 85 (34); HRMS: calcd
for C10H11IS 289.9626, found 289.9606.
General procedure 4 – Reaction of carbene complexes
with sodium iodide/chlorotrimethylsilane. To a solution
of the carbene complex (0.07–0.17 mmol, 1 eq) in dichlo-
romethane (10 mL) at 0 °C under nitrogen was added a
suspension of sodium iodide (3 eq) and chlorotrimeth-
ylsilane (3 eq) in dichloromethane (5 mL). The reaction
mixture was stirred at 0 °C for 12 h. Final purification
was achieved by flash chromatography on silica gel
using pure hexane as the eluent.
Reaction of carbene complex 4a with sodium iodide/
chlorotrimethylsilane. General procedure 4 was followed
using carbene complex 4a (0.025 g, 0.07 mmol), chloro-
trimethylsilane (0.023 g, 0.21 mmol) and sodium iodide
(0.032 g, 0.21 mmol). Chromatographic purification
afforded a colorless compound identified as diiodide
27a (0.020 g, 70% yield). Diiodide 27a: 1H NMR
(CDCl3): major (Z) isomer d 6.24 (t, 1H, J = 6.7), 2.79
(td, 2H, J = 7.0, 6.7); minor (E) isomer d 6.80 (t, 1H,
J = 7.2), 2.93 (m, 2H); the following peaks overlap in
both isomers 7.9–7.29 (m, 5H), 3.20 (t, 2H, J = 7.0) ;
13C NMR (CDCl3): d 143.7, 134.5, 131.1, 129.2, 127.9,
95.5, 41.0, 1.7 (peaks for the minor isomer did not ap-
pear); Mass Spec (EI): 416 (M, 18), 326 (21), 289
(100), 254 (49), 217 (33), 184 (17), 161 (30), 147 (13),
127 (48), 109 (35); HRMS: calcd for C10H10I2S
415.8593, found 415.8588. Integration of the alkene
peaks revealed that this is a 93:7 Z:E mixture.
Reaction of carbene complex 4a with iodine. General
procedure 3 was followed using carbene 4a (0.128 g,
0.36 mmol) and iodine (0.096 g, 0.38 mmol). Chromato-
graphic purification afforded a colorless compound
identified as diiodide 27c (0.118 g, 78% yield). The spec-
tral data were identical to that from the product of reac-
tion of carbene complex 4a and sodium iodide/
chlorotrimethylsilane. Integration of the alkene peaks
revealed that this is a 97:3 Z:E mixture.
Reaction of carbene complex 4a with pyridinium bro-
mide perbromide. General procedure 3 was followed
using carbene 4a (0.022 g, 0.06 mmol) and pyridinium
bromide perbromide (0.024 g, 0.07 mmol). Chromato-
graphic purification afforded a colorless compound
identified as dibromide 39 (0.012 g, 61% yield). Dibro-
1
mide 39. H NMR (CDCl3): major (Z) isomer d 6.46
(t, 1H, J = 6.8 Hz), 2.83 (q, 2H, J = 6.8 Hz); minor
(E) isomer d 6.55 (t, 1H, J = 7.2 Hz), 2.93 (dt, 2H,
J = 7.2, 6.8 Hz); the following peaks are overlapping
in both isomers d 7.45–7.20 (m, 5H), 3.44 (t, 2H,
J = 6.8 Hz); 13C NMR (CDCl3): d 141.1, 137.4, 133.4,
130.6, 127.9, 119.9, 35.9, 30.0; Mass Spec (EI): 324 (M
81Br2, 4), 322 (M 81Br79Br, 15), 320 (M 79Br2, 7), 243
(23), 232 (17), 178 (20), 161 (61), 147 (100), 128 (92),
109 (86); HRMS: calcd for C10H1079Br2S 319.8870,
Reaction of carbene complex 4c with sodium iodide/
chlorotrimethylsilane. General procedure 4 was followed
using carbene complex 4c (0.025 g, 0.05 mmol), chloro-
trimethylsilane (0.019 g, 0.17 mmol) and sodium iodide
(0.025 g, 0.17 mmol). Chromatographic purification
afforded a colorless compound identified as diiodide

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M.D. Reid et al. / Journal of Organometallic Chemistry 690 (2005) 5759–5776
found 319.9949. Integration of the alkene peaks revealed
that this is a 93:7 Z:E mixture.
identified as diiodide 27c (0.020 g, 82% yield). The spec-
tral data were identical to that from the product of reac-
tion of carbene complex 4c and sodium iodide/
chlorotrimethylsilane. Integration of the alkene peaks
revealed that this is a 93:7 Z:E mixture.
Reaction of carbene complex 4d with iodine. General
procedure 3 was followed using carbene 4d (0.018 g,
0.04 mmol) and iodine (0.011 g, 0.04 mmol). Chromato-
graphic purification afforded a colorless compound
identified as diiodide 27d (0.015 g, 74% yield). The spec-
tral data were identical to that from the product of reac-
tion of carbene complex 4d and sodium iodide/
chlorotrimethylsilane. Integration of the alkene peaks
revealed that this is a 75:25 Z:E mixture.
Reaction of carbene complex 4e with iodine. General
procedure 3 was followed using carbene 4e (0.021 g,
0.05 mmol) and iodine (0.015 g, 0.06 mmol). Chromato-
graphic purification afforded a colorless compound
identified as diiodide 27e (0.020 g, 82% yield). Diiodide
27e: 1H NMR (CDCl3): d major (E) isomer: 6.95 (t, 1H,
J = 7.2 Hz), 2.71 (d, 2H, J = 7.2 Hz); minor (Z) isomer:
d 6.40 (t, 1H, J = 6.8 Hz), 2.57 (d, 2H, J = 6.8 Hz); the
following peaks are overlapping in both isomers: d 7.66–
7.26 (m, 5H), 1.92 (s, 6H), This compound was very
unstable and could not be further characterized. Inte-
gration of the alkene peaks revealed that this is a
19:81 Z:E mixture.
Reaction of carbene complex 4a with phenyl selenenyl
chloride. General procedure 3 was followed using car-
bene 4a (0.180 g, 0.51 mmol) and phenyl selenenyl chlo-
ride (0.117 g, 0.61 mmol). Chromatographic purification
afforded two fractions. The product in the first fraction
was identified as dichloride 41 (0.046 g, 39% yield). The
product in the second fraction was identified as selenide
40 (0.083 g, 46% yield). 1,4-dichloro-1-thiophenyl-1-bu-
tene (41): 1H NMR (CDCl3): major (Z) isomer d 6.23 (t,
1H, J = 6.9 Hz), 2.70 (dt, 2H, J = 6.9, 6.6 Hz); minor
(E) isomer d 6.24 (t, 1H, J = 7.4 Hz), 2.80 (dt, 2H,
J = 7.4, 6.6 Hz); the following peaks are overlapping
in both isomers d 7.40–7.19 (m, 5 H), 3.53 (t, 2H,
J = 6.6 Hz); 13C NMR (CDCl3): d 135.5, 133.2, 132.7,
130.7, 129.2, 127.8, 42.4, 33.2; Mass Spec (EI): 236 (M
37Cl2, 11), 234 (M 37Cl35Cl, 54), 232 (M 35Cl2, 78), 197
(28), 183 (66), 147 (100), 125 (16), 109 (25); HRMS:
calcd for C10H1035Cl2S 231.9880, found 231.9888. Inte-
gration of the alkene peaks revealed that this is a 97:3
Z:E mixture. 4-Chloro-1-phenylseleno-1-phenylthio-1-
1
butene (40). H NMR (CDCl3): d 7.50–7.15 (m, 10H),
6.25 and 6.16 (two tÕs, total of 1H, J = 7.1), 3.46 and
3.45 (two tÕs, total of 2H, J = 6.7), 2.74 (m, 2 H); 13C
NMR (CDCl3): d 139.0, 136.5, 134.4, 133.0, 131.8,
130.1, 129.1, 128.9, 128.8, 128.1, 127.6, 127.5, 126.9,
43.2, 35.8, 34.4; Mass Spec (EI): 354 (M, 59), 197 (91),
161 (72), 147 (20), 128 (100), 121 (59), 107 (28); HRMS:
calcd for C16H15ClS80Se 353.9748, found 353.9738. Inte-
gration of the alkene peaks revealed that this is a 50:50
Z:E mixture.
Reaction of carbene complex 4e with pyridinium bro-
mide perbromide. General procedure 3 was followed
using carbene 4e (0.176 g, 0.46 mmol) and pyridinium
bromide perbromide (0.155 g, 0.48 mmol). Chromato-
graphic purification afforded a colorless compound
identified as dibromide 42 (0.035 g, 22% yield). 1,4-di-
Reaction of carbene complex 4b with iodine. General
procedure 3 was followed using carbene complex 4b
(0.030 g, 0.07 mmol) and iodine (0.022 g, 0.09 mmol).
Chromatographic purification afforded a colorless com-
pound identified as Diiodide 27b (0.028 g, 85% yield).
1
bromo-4-methyl-1-thiophenyl-1pentene (42): H NMR
(CDCl3): d major (E) isomer: 6.67 (t, 1H, J = 7.4 Hz),
2.81 (d, 2H, J = 7.4 Hz); minor (Z) isomer: d 6.58 (t,
1H, J = 6.8 Hz), 2.72 (d, 2H, J = 6.8 Hz); the following
peaks are overlapping in both isomers: d 7.35–7.26 (m,
5H), 1.73 (s, 6H), 13C NMR (CDCl3): d 141.0, 138.0,
133.2, 130.0, 129.1, 127.5, 116.7, 64.3, 50.1, 48.9, 34.1;
Mass Spec (EI): 352 (M+4, 34), 250 (M+2, 66), 348
(M+, 32), 294 (19), 271 (58), 227 (70), 190 (41), 147
(100), 134 (40), 109 (14); HRMS: calcd for
C12H1481Br79BrS 349.9162, found 349.9156. Integration
of the alkene peaks revealed that this is a 20:80 Z:E
mixture.
1
Diiodide 27b: H NMR (CDCl3): major (Z) isomer: d
6.00 (d, 1H, J = 9.1 Hz), 4.00 (td, 1H, J = 11.4, 4.0
Hz), 2.72 (m, 1H); minor (E) isomer: d 6.55 (d, 1H,
J = 9.6 Hz), 3.90 (td, 1H, J = 11.2, 4.1 Hz), 3.15 (m,
1H); the following peaks are overlapping in both iso-
mers: d 7.48–7.19 (m, 5H), 2.45 (m, 1H), 2.00 (m, 1H),
1.92–1.77 (m, 2H), 1.59–1.03 (m, 4H); Irradiate at d
2.72: d 6.00 (s), 4.00 (dd, 1H, J = 11.4, 4.0); 13C NMR
(CDCl3): d 156.6, 150.4, 135.2, 130.5, 130.4, 129.1,
127.5, 91.9, 86.1, 56.2, 52.1, 40.0, 35.3, 34.6, 33.6, 32.3,
28.2, 24.7; Mass Spec (EI): 470 (M, 44), 344 (49), 275
(54), 354 (36), 218 (46), 162 (48), 147 (70), 123 (100),
107 (86); HRMS: calcd for C14H16I2S 469.9062, found
469.9073. Integration of the alkene peaks revealed that
this is a 72:28 Z:E mixture.
Reaction of carbene complex 4f-cis with iodine. Gen-
eral procedure 3 was followed using carbene 4f-cis
(0.031 g, 0.07 mmol) and iodine (0.019 g, 0.07 mmol).
Chromatographic purification afforded a colorless com-
pound identified as diiodide 27f (0.025 g, 71% yield).
1
Diiodide 27f. H NMR (CDCl3): major (E) isomer: d
Reaction of carbene complex 4c with iodine. General
procedure 3 was followed using carbene 4c (0.021 g,
0.05 mmol) and iodine (0.015 g, 0.06 mmol). Chromato-
graphic purification afforded a colorless compound
6.92 (t, 1H, J = 7.1 Hz), 2.93 (t, 2H, J = 7.1 Hz), 1.50
(m, 1 H); minor (Z) isomer: 6.35 (t, 1H, J = 6.6 Hz),
2.80 (t, 2H, J = 6.6 Hz), 1.86 (m, 1H); the following
peaks are overlapping in both isomers: d 7.39–7.31 (m,

M.D. Reid et al. / Journal of Organometallic Chemistry 690 (2005) 5759–5776
5773
5H), 4.13 (m,1H), 1.71 (m,1H), 1.38–1.14 (m, 8H), 0.92–
0.84 (m, 3H); 13C NMR (CDCl3): d 150.4, 144.2, 135.1,
130.9, 130.3, 129.2, 129.2, 129.1, 127.6, 127.5, 127.2,
87.5, 47.9, 43.5, 40.3, 34.7, 31.6, 29.5, 28.4, 14.0, 1.0;
Mass Spec (EI): 500 (M, 14), 374 (18), 373 (100), 275
(100), 246 (23), 147 (33), 134 (13), 115 (111); HRMS:
calcd for C16H22I2S 499.9532, found 499.9548. Integra-
tion of the alkene peaks revealed that this is a 17:83
Z:E mixture.
Reaction of carbene complex 4f-trans with iodine.
General procedure 3 was followed using carbene com-
plex 4f-trans (0.043 g, 0.10 mmol) and iodine (0.026 g,
0.10 mmol). Chromatographic purification afforded a
colorless compound identified as an inseparable mixture
of diiodides 27f and 38f (0.025 g, 76% yield). Diiodide
38f (peaks for the major component of the mixture,
27f are not listed). 1H NMR (CDCl3): Major (Z) isomer:
d 6.01 (d, 1H, J = 8.9 Hz); minor (E) isomer: d 6.57 (d,
1H, J = 9.4 Hz); the following peaks are overlapping in
both isomers: d 7.39–7.31 (m, 5H), 3.20 (dd, 2H, J = 5.9,
3.8 Hz), 2.50 (m, 1H), 1.50–1.20 (m, 6H), 0.92–0.84 (m,
5H); 13C NMR (CDCl3): d 143.7, 134.5, 131.1, 129.2,
127.9, 95.5, 41.0, 1.7 (peaks for compound 27f have been
subtracted out). Integration of the alkene peaks revealed
that 27f is an 84:16 Z:E mixture, and that 38f is a 96:4
Z:E mixture.
Preparation of carbene complex 4i and subsequent
reaction with iodine. General procedure 2 was followed
using carbene acylate 1b (0.500 g, 1.28 mmol), 2-methyl-
thiophenol (0.152 mL, 1.28 mmol), and acetyl chloride
(0.91 mL, 1.28 mmol). After chromatographic purifica-
tion a red solid identified as carbene complex 4i (0.119
g, 22% yield) was obtained. This solid was immediately
used in the next experiment. General procedure 3 was
followed using carbene complex 4i (0.016 g, 0.038 mmol)
and iodine (0.010 g. 0.040 mmol). After chromato-
graphic purification
a colorless oil identified as
compound 27i (0.018 g, 99% yield) was obtained. Diio-
1
dide 27i: H NMR (CDCl3): major (Z) isomer: 5.87 (d,
1H, J = 8.8 Hz), minor (E) isomer: 6.59 (d, 1H,
J = 9.5 Hz); the following peaks are overlapping in both
isomers: 7.45–7.10 (m, 4H), 4.00 (dt, 1H, J = 10.8, 4.0
Hz); 2.78 (tdd, 1H, 10.8, 8.8, 3.8 Hz), 2.53–2.30 (m,
2H) overlapping with 2.40 (s, 3H), 2.05 (qd, 1H, 10.8,
3.8 Hz), 2.85 (m, 2H), 1.53 (m, 2H); 13CNMR (ppm):
147.4, 139.7, 132.6, 130.6, 128.3, 126.6, 92.3, 77.2,
56.1, 39.9, 34.9, 33.5, 32.5, 29.7, 28.3, 24.8, 20.6; Mass
Spec (EI): 484 (M+, 9), 441 (2), 357 (100), 229 (78),
127 (51); HRMS: calcd for C15H18I2S 483.9219, found
483.9213. Integration of the alkene peaks revealed that
this product is a 91:9 Z:E mixture.
Preparation of carbene complex 4j and subsequent
reaction with iodine. General procedure 2 was followed
using carbene acylate 1b (0.550 g, 1.41 mmol), 3-methyl-
thiophenol (0.168 mL, 1.41 mmol), and acetyl chloride
(0.100 mL, 1.41 mmol). After chromatographic purifica-
tion a red solid identified as carbene complex 4j (0.241 g,
Reaction of diiodide 27b with n-butyllithium followed
by protonation – Proof of alkene stereochemistry. To a
solution of diiodide 27b (0.075 g, 0.16 mmol) in THF
(30 mL) under nitrogen at À78 °C was added via syringe
n-butyllithium (0.12 mL of a 1.6 M hexane solution, 1.9
mmol) and the mixture was stirred at À78 °C for 5 min
after completion of the addition. Water (1 mL) was
added and the solution was allowed to warm to room
temperature. The reaction mixture was poured into a
separatory funnel containing water and ether. The ether
layer was dried over sodium sulfate and the solvent was
removed on a rotary evaporator. Final purification was
achieved by flash chromatography on silica gel using
pure hexane as the eluent to afford the monoidodo vinyl
1
40% yield). Carbene complex 4j: H NMR (CDCl3): d
7.40–7.10 (m, 4H), 2.72 (br s, 3H), 2.38 (s, 3H), 2.35
(m, 1H), 2.00 (m, 2H), 1.53 (m, 2H), 1.20 (m, 2H),
0.86 (t, 2H). This solid was immediately used in the next
experiment. General procedure 3 was followed using
carbene complex 4j (0.148 g, 0.35 mmol) and iodine
(0.093 g. 0.037 mmol). After chromatographic purifica-
tion a colorless oil identified as diiodide 27j (0.166 g,
100% yield) was obtained. Diiodide 27j: 1H NMR
(CDCl3): major (Z) isomer: d 6.06 (d, 1H, J = 9.2 Hz),
4.05 (td, 1H, J = 11.0, 3.8 Hz), 2.80 (tdd, 1H,
J = 11.0, 9.2, 3.8 Hz), 2.38 (s, 3H); minor (E) isomer:
d 6.63 (d, 1H, J = 9.4 Hz), 4.02 (td, 1H, J = 11.0, 3.8
Hz), 3.25 (tdd, 1H, J = 11.0, 9.4, 3.8 Hz), 2.39 (s, 3H);
the following peaks are overlapping both isomers:7.35–
7.10 (m, 4H), 2.55 (br d, 1H, J = 11.0 Hz), 2.20–1.30
(m, 7H); 13CNMR (CDCl3): d 156.6, 139.0, 130.9,
128.9, 127.5, 56.3, 52.1, 40.0, 39.9, 35.4, 34.8, 33.6,
32.3, 28.3, 24.9, 24.8, 21.4. Integration of the alkene
peaks revealed that this product is a 69:31 Z:E mixture.
Preparation of carbene complex 4k and subsequent
reaction with iodine. General procedure 2 was followed
using carbene acylate 1b (0.533 g, 1.37 mmol), ethaneth-
iol (0.101 mL, 1.37 mmol), and acetyl chloride (0.097
mL, 1.37 mmol). After chromatographic purification a
1
sulfide 43 (0.024 g, 44% yield). Iodo vinyl sulfide 43: H
NMR (CDCl3): major (trans) isomer: d 6.08 (d, 1H,
J = 14.8 Hz), 5.68 (dd, 1H, J = 14.8, 8.7 Hz), 3.86 (td,
1H, J = 11.3, 4.2 Hz), 2.44 (m, 1H); minor (cis) isomer:
d 6.14 (d, 1H, J = 8.7 Hz), 5.52 (t, 1H, J = 8.7 Hz), 3.95
(td, 1H, J = 11.6, 4.1 Hz), 2.93 (m, 1H); the following
peaks are overlapping in both isomers: d 7.34–7.09 (m,
5H), 2.52–2.36 (m, 1H), 1.95 (m, 1H), 1.98–1.64 (m,
2H), 1.52–1.04 (m, 4H); 13C NMR (CDCl3): d 140.0,
137.8, 136.0, 129.2, 129.1, 126.3, 123.5, 123.0, 51.7,
48.1, 40.5, 40.2, 38.1, 37.3, 33.8, 33.3, 29.7, 28.5, 25.2,
25.1; Mass Spec (EI): 344 (M+, 30), 217 (37), 181
(100), 149 (21), 123 (32), 109 (21); HRMS: calcd for
C14H17IS 344.0096, found 344.0096. Integration of the
alkene peaks revealed that this is a 70:30 trans:cis
mixture.

5774
M.D. Reid et al. / Journal of Organometallic Chemistry 690 (2005) 5759–5776
red solid identified as carbene complex 4k (0.494 g, 41%
yield). The NMR spectrum of this compound was signif-
icantly broadened; this material was utilized immedi-
ately in the next reaction. General procedure 3 was
followed using carbene complex 4k (0.111 g, 0.31 mmol)
and iodine (0.082 g. 0.032 mmol). After chromato-
graphic purification a colorless oil identified as com-
pound 27k (0.107 g, 82% yield) was obtained. Diiodide
J = 6.7 Hz), 2.40 (t, 2H, J = 7.0 Hz), 2.11 (tt, 2H,
J = 7.0, 6.7 Hz). The spectral data were consistent with
those previously reported for this compound [40].
Reaction of carbene complex 47 with iodine. General
procedure 3 was followed using carbene complex 47
[25] (0.073 g, 0.222 mmol) and iodine (0.059 g, 0.233
mmol). Chromatographic purification afforded a color-
less compound identified as 1-iodo-1-thiophenylethylene
(48) (0.0257 g, 44% yield). The product turns black upon
brief standing at room temperature. 1-iodo-1-thiophe-
nylethylene (48). 1H NMR (CDCl3): d 7.56–7.39 (m,
5H), 6.34 (d, 1H, J = 2.1 Hz), 6.09 (d, 1H, J = 2.1
Hz), 13C NMR (CDCl3): d 132.5, 130.0, 129.4, 128.7,
127.6, 95.1; IR (CH2Cl2): 3156 (m), 3056 (w), 1644
(m), 1465 (vs), 1381 (m), 1263 (m), 1100 (m) cmÀ1: Mass
Spec (CI): 262 (M, 6), 135 (100), 134 (37), 127 (60), 110
(59), 109 (57): HRMS: Calc for C8H7IS 261.9313, found
261.9331.
1
27k: H NMR (CDCl3): major (Z) isomer d 5.85 (d,
1H, J = 8.9 Hz), 3.92 (td, 1H, J = 11.0, 4.0 Hz); minor
(E) isomer: 6.43 (d, 1H, J = 9.5 Hz), 3.89 (td, 1H,
J = 11.0, 4.0 Hz) 3.09 (tdd, 1H, J = 11.0, 9.5, 4.0 Hz);
the following peaks are overlapping in both isomers: d
2.85–2.58 (m, 3.5H), 2.48 (dq, 1H, J = 11.0, 4.0 Hz),
2.20–1.05 (m, 6H) overlapping with 1.25 (t, 3H,
J = 7.4 Hz – two sets of lines); 13CNMR (ppm): 154.6,
147.4, 95.2, 90.6, 77.6, 76.9, 76.3, 56.0, 51.7, 39.9, 39.8,
35.6, 34.9, 33.1, 32.3, 32.0, 30.6, 28.2, 24.8, 14.9, 14.3;
MS (EI): 422 (M+, 6), 336 (2), 295 (100), 227 (40), 167
(29), 127 (30); HRMS: calcd for C10H16I2S 421.90622,
found 421.9067. Integration of the alkene peaks revealed
that this product is a 51:49 Z:E mixture.
Preparation of carbene complex 4l and subsequent
reaction with iodine. General procedure 2 was followed
using carbene acylate 1b (0.314 g, 0.81 mmol), 2-pro-
panethiol (0.075 mL, 0.81 mmol), and acetyl chloride
(0.057 mL, 0.81 mmol). After chromatographic purifica-
tion a red solid identified as carbene complex 4l (0.092 g,
36% yield). The NMR spectrum of this compound was
significantly broadened; this material was utilized imme-
diately in the next reaction. General procedure 3 was
followed using carbene complex 4l (0.078 g, 0.24 mmol)
and iodine (0.064 g. 0.025 mmol). After chromato-
Reaction of carbene complex 49 with iodine. General
procedure 3 was followed using carbene complex 49
[15] (0.331 g, 0.849 mmol) and iodine (0.216 g, 0.849
mmol). Chromatographic purification afforded a color-
less solid identified as 1,2-bis(thiophenyl)stilbene (50)
(0.088 g, 56% yield). 1,2-bis(thiophenyl)stilbene (50).
1
mp 54–55 °C. H NMR (CDCl3): d 8.08–8.02 (m, 4H),
7.62 (m, 2H), 7.45–7.42 (m, 14H); 13C NMR (CDCl3):
d 189.9, 136.6, 135.0, 133.5, 129.4, 129.1, 128.7, 127.4;
IR (CH2Cl2): 3069 (s), 3038 (w), 1681 (vs), 1581 (s),
1450 (s), 1206 (s), 1175 (s), 1025 (m); Mass Spec (EI):
396 (M+, 89), 287 (52), 210 (43), 178 (65), 105 (100);
HRMS: calcd for C26H20S2 396.1001, found 396.0994.
Note: The Carbon-13 spectrum for this compound has
been calculated and the peak at d 189.9 is not consistent
with the proposed structure. We however feel that in a
compound where the NMR is of such limited utility
(all protons/carbons aromatic), the mass spectrum is
the best indication of structure. High resolution analysis
of key fragment ions is also consistent with this struc-
ture. Peak at 289 (MÀC6H5S): calcd for C20H15S
287.0894, found 287.0918. Peak at 178 (diphenylacety-
lene): calcd for C14H10 178.0782, found 178.1770.
graphic purification
a colorless oil identified as
compound 27l (0.092 g, 87% yield) was obtained. Diio-
1
dide 27l: H NMR (CDCl3): major (Z) isomer: d 5.87
(d, 1H, J = 8.9 Hz), 4.02 (td, 1H, J = 11.0, 4.0 Hz),
2.72 (tdd, 1H, J = 11.0, 8.9, 4.0 Hz); minor (E) isomer:
d 6.42 (d, 1H, J = 9.4 Hz), 3.91 (td, 1H, J = 11.0, 4.0
Hz), 3.09 (tdd, 1H, J = 11.0, 9.4, 4.0 Hz); the following
peaks are overlapping in both isomers: d 3.26 (septet,
1H, J = 6.5 Hz), 2.47 (dq, 1H, J = 11.0, 4.0 Hz), 2.15–
1.50 (m, 6H), 1.40–1.18 (m, 6H); 13CNMR (CDCl3): d
154.8, 149.1, 100.8, 95.1, 56.2, 51.7, 41.8, 49.9, 39.9,
39.8, 35.7, 34.8, 33.3, 32.3, 28.2, 24.8, 23.1, 22.9, 22.2,
21.6; Mass Spec (EI): 436 (M+, 10), 309 (100), 267
(54), 199 (48), 139 (53); HRMS: calcd for C11H18I2S
435.9219, found 435.9256. Integration of the alkene
peaks revealed that this product is a 52:48 Z:E mixture.
Reaction of alkoxycarbene complex 44 with iodine.
General procedure 3 was followed using carbene 44
(0.080 g, 0.29 mmol) and iodine (0.083 g, 0.33 mmol).
Chromatographic purification using 19:1 hexane: ethyl
acetate afforded a colorless compound identified as iodo-
ester 46 (0.029 g, 41% yield). Methyl 4-iodobutanoate
Sonogashira coupling of diiodide 27a with 1-hexyne. A
mixture of diiodide 27a (0.150 g, 0.361 mmol), palla-
dium chloride (0.005 g, 0.028 mmol), triphenylphos-
phine (0.010 g, 0.038 mmol), 1-hexyne (0.22 mL, 1.901
mmol), and copper(I) iodide (0.007 g, 0.037 mmol) in
diethylamine (5 mL) was stirred for 20 h at 45 °C. The
solvent was evaporated, and the residue was dissolved
in ethyl acetate. The resulting suspension was filtered
through Celite and solvent was removed on a rotary
evaporator. Flash chromatography of the residue using
pure hexane as the eluent afforded a colorless oil identi-
fied as dienyne 51 (0.080 g, 92% yield). This oil quickly
1
darkened. Dienyne 51. H NMR (CDCl3): d 7.41 (br d,
2H, J = 6.4 Hz), 7.31 (m, 3H ), 6.78 (dt, 1H, J = 17.2,
10.4 Hz), 6.48 (d, 1H, J = 10.4 Hz ), 5.27 (d, 1H,
1
(46): H NMR (CDCl3): d 3.67 (s, 3H), 3.22 (t, 2H,

M.D. Reid et al. / Journal of Organometallic Chemistry 690 (2005) 5759–5776
5775
(c) H.N.C. Wong, Y. Moon, C.W. Tse, Y.C. Yip, J. Tanko, T.
Hudlicky, Chem. Rev. 89 (1989) 165–198;
(d) J. Salaun, Top. Curr. Chem. 207 (2000) 1–67.
[2] S. Danishefsky, Acc. Chem. Res. 12 (1979) 66–72.
[3] (a) R.D. Miller, D.R. McKean, J. Org. Chem. 46 (1981) 2412–
2414;
J = 17.2 Hz), 5.19 (d, 1H, J = 10.4 Hz), 2.28 (t, 2H,
J = 6.8 Hz ), 1.38 (quintet, 2H, J = 6.8 Hz), 1.26 (sextet,
2H J = 6.8 Hz), 0.83 (t, 3H, J = 6.8 Hz ); 13C NMR
(CDCl3): d 137.3, 134.4, 133.4, 132.5, 129.0, 127.8,
120.1, 119.1, 99.6, 76.7, 30.6, 22.0, 19.5, 13.8. Mass Spec
(ESI): 265 (M + Na).
(b) H. Huang, C.J. Forsyth, Tetrahedron 53 (1997) 16341–
16348.
Stille coupling of diiodide 17a and tributyl(phenyl-
ethynyl)stannane. Diiodide 27a (0.250 g, 0.600 mmol)
was dissolved in DMF (5 mL) at 25 °C. To the solution
was added bis(acetonitrile)palladium(II) chloride (0.008
g, 0.03 mmol) and the solution was stirred for 5 min at
25 °C. Tributyl(phenylethynyl)stannane (0.282 g, 0.721
mmol) was added and the solution immediately turned
black. The reaction was stirred an additional 30 min
and the diluted with ether (25 mL). The mixture was
placed in a separatory funnel and washed with water.
The ether layer was dried over sodium sulfate and the
solvent was removed on a rotary evaporator. The resi-
due was purified by flash chromatography on silica gel
using pure hexane as the eluent. Three fractions were
isolated. The product in the first fraction was the start-
ing alkynylstannane (0.025 g, 6% recovery). The product
in the second fraction was the starting diiodide 27a
(0.105 g, 46% recovery). The product in the third
fraction was identified as enyne 51 (0.084 g, 34% yield).
Enyne 51: 1H NMR (CDCl3): d 7.49–7.62 (m, 2H), 7.38–
7.21 (m, 8H), 6.16 (t, 1H, J = 7.3 Hz), 3.23 (t, 2H,
J = 7.3 Hz), 3.02 (q, 2H, J = 7.3 Hz); 13C NMR
(CDCl3): d 139.4, 132.1, 131.5, 128.9, 128.6, 128.2,
127.6, 122.4, 119.7, 96.3, 90.0, 84.7, 35.3, 3.0; Mass Spec
(EI): 390 (M+, 29), 263 (100), 254 (34), 218 (14), 153
(25), 152 (19), 129 (54), 127 (25), 109 (32); HRMS: calcd
for C18H15IS 389.9939, found 389.9936.
[4] We note that carbene complexes that feature an additional
electron-withdrawing group have been examined. J.D. Carter,
T.K. Schoch, L. McElwee-White, Organometallics 11 (1992)
3571–3578.
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following papers: (a) T.R. Hoye, G.M. Rehberg, Organometallics
8 (1989) 2070–2071;
(b) P. Korkowski, T.R. Hoye, D.B. Rydberg, J. Am. Chem. Soc.
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[14] J.A. Connor, E.M. Jones, J. Chem. Soc. A (1971) 1974–1979.
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105 (1972) 150–161.
[16] A literature search reveals that all of the monobromocyclopro-
panes used in this manuscript have been reported in numerous
manuscripts. Thus, only the general procedure is offered. To a
solution of dibromocyclopropane (10 mmol) in acetic acid (25
mL) at 25 °C was added powdered zinc (40 mmol) slowly over a 2
h period. After the addition was complete the mixture was stirred
for an additional 1h period. The mixture was then filtered and
Acknowledgements
This research was supported by the Petroleum
Research Fund, Administered by the American
Chemical Society, and the SCORE Program of NIH.
Fellowship support to MDR through the NIH predoc-
toral fellowship program, to LT through the MARC
Program of NIH at the University of Puerto Rico, and
to ND through the Howard Hughes Medical Institute
Program at the University of Maryland is gratefully
acknowledged. We are deeply indebted to Ms. Clare
Buckingham for assistance in preparation of this manu-
script. We also thank the reviewers for their careful
attention to the manuscript.
added to saturated aqueous sodium chloride solution in
a
separatory funnel. The solution was extracted with pentane and
the pentane layer was washed three times with 1M sodium
hydroxide solution. The pentane layer was dried over sodium
sulfate and the solvent was removed on a rotary evaporator. The
resulting monobromocyclopropane was used without further
purification. The procedure was adapted from: E. Piers, H.E.
Morton, I. Nagakura, W. Thies, Can. J. Chem. 61 (1983) 1226–
1238.
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(1963) 703–706.
[18] This reagent was selected due to its ability to induce the opening of
cyclopropylketones. See reference [3a].
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