Palladium-Catalyzed Synthesis of α-Carbonyl-α′-(hetero)aryl Sulfoxonium Ylides: Scope and Insight into the Mechanism

Article abstract of DOI:10.1021/acs.joc.9b03032

Despite recent advances, a general method for the synthesis of α-carbonyl-α′-(hetero)aryl sulfoxonium ylides is needed to benefit more greatly from the potential safety advantages offered by these compounds over the parent diazo compounds. Herein, we report the palladium-catalyzed cross-coupling of aryl bromides and triflates with α-carbonyl sulfoxonium ylides. We also report the use of this method for the modification of an active pharmaceutical ingredient and for the synthesis of a key precursor of antagonists of the neurokinin-1 receptor. In addition, the mechanism of the reaction was inferred from several observations. Thus, the oxidative addition complex [(XPhos)PhPdBr] and its dimer were observed by ³¹P{¹H} NMR, and these complexes were shown to be catalytically and kinetically competent. Moreover, a complex resulting from the transmetalation of [(XPhos)ArPdBr] (Ar = p-CF₃-C₆H₄) with a model sulfoxonium ylide was observed by mass spectrometry. Finally, the partial rate law suggests that the transmetalation and the subsequent deprotonation are rate-determining in the catalytic cycle.

Full text of DOI:10.1021/acs.joc.9b03032

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Article
Palladium-Catalyzed Synthesis of #-Carbonyl-#’-(Hetero)aryl
Sulfoxonium Ylides: Scope and Insight into the Mechanism
Christopher Janot, Jean-Baptiste Chagnoleau, Nathan R. Halcovitch, James C. Muir, and Christophe Aissa
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.9b03032 • Publication Date (Web): 06 Dec 2019
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Palladium-Catalyzed Synthesis of α-Carbonyl-α’-
(Hetero)aryl Sulfoxonium Ylides: Scope and Insight
into the Mechanism
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Christopher Janot,† Jean-Baptiste Chagnoleau,† Nathan R. Halcovitch,‡ James Muir,§ and
Christophe Aïssa*,†.
† Department of Chemistry, University of Liverpool, Crown Street, L69 7ZD, United Kingdom.
‡
Department of Chemistry, Lancaster University, Bailrigg, Lancaster, LA1 4YB, United
Kingdom.
§ Pharmaceutical Technology and Development, AstraZeneca Macclesfield Campus, Cheshire,
SK10 2NA, United Kingdom.
*E-mail: aissa@liverpool.ac.uk
ABSTRACT. Despite recent advances, a general method for the synthesis of α-carbonyl-α’-
(hetero)aryl sulfoxonium ylides is needed to benefit more greatly from the potential safety
advantages offered by these compounds over the parent diazo compounds. Herein, we report the
palladium-catalyzed cross-coupling of aryl bromides and triflates with α-carbonyl sulfoxonium
ylides. We also report the use of this method for the modification of an active pharmaceutical
ingredient and to the synthesis of a key precursor of antagonists of the neurokinin-1 receptor. In
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addition, the mechanism of the reaction was inferred from several observations. Thus, the
oxidative addition complex [(XPhos)PhPdBr] and its dimer were observed by 31P{1H} NMR and
these complexes were shown to be catalytically and kinetically competent. Moreover, a complex
resulting from the transmetallation of [(XPhos)ArPdBr] (Ar = p-CF3-C6H4) with a model
sulfoxonium ylide was observed by mass spectrometry. Finally, the partial rate law suggests that
the transmetallation of and the subsequent deprotonation are rate-determining in the catalytic
cycle.
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TOC graphic
[(XPhos)ArPdBr]
observed by 31P NMR
ArPd(XPhos) ArPd(XPhos)
[(XPhos)ArPdBr]
½
2
O
O
(Het)Ar-Br/OTf
S
Pd
R
(Het)Ar
O
R
O
O
O
O
or
S
S
S
H
O
R
R
observed by mass spectrometry
Examples
O
O
O
S
Ph
Ph
S
O
O
S
O
S
O
O
Ph
BocHN
Ph
Ph
Ph
NMe2
O
H
3
CN
O
2
O
INTRODUCTION
Metal-catalyzed reactions of sulfoxonium ylides have recently enjoyed a renaissance1–5 that is
encouraged by the potential utility of these methods for the multi-kilogram synthesis of drug
candidates.6 Hence, intensive efforts have been recently directed to the development of catalytic
methods for the formation of carbon-carbon7–28 and carbon-heteroatom29–36 bonds from these
ylides. Moreover, comparison of the energy released in differential scanning calorimetry studies
clearly demonstrates the potential safety advantages offered by α-carbonyl sulfoxonium ylides
over the parent diazo compounds.7,8
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Scheme 1. Synthetic utility of α-carbonyl-α’-(hetero)aryl sulfoxonium ylides and their
5
6
preparation by palladium-catalyzed cross-coupling.
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a) Value of -carbonyl-'-(hetero)aryl sulfoxonium ylides (ref 34)
H2N
O
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O
Ph
Ph
N2
NHPh
i-Pr NHPh
Ir
catalyst
O
O
O
Rh
catalyst
Ph
S
i-Pr
N
DMSO
TsOH
F
H
F
F
b) This work
O
O
S
O
S
Pd catalyst
(Het)Ar-Br/OTf
O
R
(Het)Ar
R
 General synthesis of -carbonyl-'-(hetero)aryl sulfoxonium ylides
 Easily accessible (hetero)aryl bromides and triflates
 Proposed mechanism inferred from observed intermediates
Significantly, most of these methods involve the use of α-carbonyl sulfoxonium ylides that have
only one substituent attached to the ylide carbon atom. A notable exception is the use of a bis-
substituted α-carbonyl-α’-aryl sulfoxonium ylide in the synthesis of an advanced pyrrole precursor
of atorvastatin (Scheme 1a),34 an anti-cholesterol top-selling drug.
However, the preparation of bis-substituted α-carbonyl-α’-(hetero)aryl sulfoxonium ylides
remains challenging and therefore limits their wider application in synthesis despite their
significant potential utility. Thus, the sulfoxonium ylide depicted in Scheme 1a was prepared by
the decomposition of an α-carbonyl-α’-aryl diazo compound in the presence of rhodium(II) acetate
under harsh conditions that are not compatible with the high thermal potential of diazo
compounds.31,37,38 Although simple α-carbonyl-α’-(hetero)aryl sulfoxonium ylides can be
prepared by reaction of arynes and α-carbonyl sulfoxonium ylides,39 this approach does not enable
easy structural variations of the (hetero)aryl group because of the necessary multi-step synthesis
of the aryne precursors and the potential regioselectivity issues typical of many intermolecular
reactions of unsymmetrical arynes.40 Moreover, although iodoniums can serve as precursors of
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sulfoxonium ylides,41 the reported method is not suitable for the synthesis of ylides bearing both
an electron-acceptor substituent and a (hetero)aryl group. As an alternative, one could consider a
two-step sequence beginning with the nucleophilic aromatic substitution of reactive heterocycles
with dimethylsulfoxonium methylide followed by an acylation,42 but it cannot be applied to the
introduction of simple aryl halides of decreased electrophilic character. Finally, the palladium-
catalyzed carbonylative arylation of α-carbonyl sulfoxonium ylides has been described with aryl
iodides, but it has not been described with less expensive aryl bromides or for the preparation of
sulfoxonium ylides that bear only one electron-withdrawing group.43 Accordingly, a general
method for the preparation of α-carbonyl-α’-(hetero)aryl sulfoxonium ylides from easily available
precursors remains needed.
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Herein, we now report the palladium-catalyzed cross-coupling of aryl bromides and triflates with
α-carbonyl sulfoxonium ylides (Scheme 1b). The synthetic utility of the method is illustrated with
the modification of an active pharmaceutical ingredient and by the synthesis of a key precursor of
antagonists of the neurokinin-1 receptor. A mechanism is proposed on the basis of control
experiments.
RESULTS AND DISCUSSION
Optimization and scope of the reaction. During our study of the palladium-catalyzed cross-
coupling of α-ester sulfoxonium ylides and aryl bromides,7 initial tests of the reactivity of α-ketone
sulfoxonium ylide 1 led us to believe that no reaction occurred because ylides 1 and 2 were not
distinguishable by thin layer chromatography. However, examination of the crude mixture by 1H
NMR confirmed that modest conversion was achieved (Table 1, entry 1). It is noteworthy that α-
ketone sulfoxonium ylides are far less reactive than the corresponding esters in this palladium-
catalyzed reaction. Nevertheless, by switching the ligand to XPhos and changing the stoichiometry
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(entry 2) and concentration (entry 3) of the reaction, we managed to reach full conversion of ylide
1 and isolate pure 2 in good yield. Moreover, it is remarkable that sulfoxonium ylide 1 was
recovered unchanged when mixed with either iodobenzene or bromobenzene and treated under the
conditions that catalyze the cross-coupling of aryl iodides with α-diazo ketones.44 Sulfoxonium
ylides and diazo compounds have therefore a very distinct reactivity in palladium-catalyzed
reactions.
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Table 1. Optimization of the reaction conditions
O
Cy2P
i-Pr
XPhos:
S
Pd catalyst
PhBr (x equiv)
i-Pr
O
S
O
O
Ph
Cy
Cs2CO3 (1.1 equiv)
MeCN, 80 °C
Cy
1
2
(y equiv)
i-Pr
entry
Pd catalyst
x/y concentration yield
1
2
3
10 mol % Pd(PPh3)4
1:1.5
0.1 M
0.1 M
0.5 M
24%a
81%b
83%c
5 mol % Pd2(dba)3 + 20 mol % XPhos 2.5:1
5 mol % Pd2(dba)3 + 20 mol % XPhos 2.5:1
a
1
b
Yield determined from H NMR of the crude mixture. Isolated as two fractions, one of them
containing 8% of recovered starting material 1. c Yield of isolated pure product. Cy = cyclohexyl.
Scope of the reaction. Although the reaction conditions were at this stage not completely
optimized with respect to the stoichiometry of reactants, we were eager to rapidly establish their
generality. We found that varying the sulfoxonium fragment was well tolerated as illustrated with
functionalized alkyl groups bearing for example an indole, a pyrrole, an ether, and Boc-protected
primary and secondary amines (Figure 1, 3–7), whereby the yields remained high throughout.
Whereas primary (3–6) and secondary (7, 8) alkyl groups were compatible, attempts for which the
R group was a tertiary alkyl group (e.g. adamantyl) led to no conversion. On the other hand,
sulfoxonium ylides bearing electron-poor (9) or electron-rich (10) aryl groups, as well as
heteroaryls (11 and 12) groups, underwent the cross-coupling in high yields. Similarly, the aryl
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bromides could be varied to give cross-coupled products 13–20 (Figure 2), although para-
bromoanisole gave 15 in a lower yield due to the decomposition of the product under the reaction
conditions. Thus, in that case, an optimal result was obtained by stopping the reaction after 2 hours.
Moreover, the coupling of heteroaryl bromides gave 21 and 22, and that of aryl triflates gave
examples 23 and 24. Finally, it is noteworthy that this protocol afforded formyl derivatives 25 and
26 in excellent yields.
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Br
O
Pd2(dba)3 (5 mol %)
XPhos (20 mol %)
O
R
S
S
O
O
Cs2CO3 (1.1 equiv)
MeCN (0.5 M), 80 °C, 16 h
R
NC
CN
3 12
–
OBn
N
NBoc
7
, 85%
NHBoc
N
3
4
5
6
, 89%
, 79%
, 80%
, 87%
CF3
Ph
S
N
Ph
O
OMe
CF3
8
9
10
11
12
, 92%
, 82%
, 80%
, 79%
, 83%
Figure 1. Scope of α-ketone sulfoxonium ylides. Yields of pure isolated products from the
reactions of aryl bromide (1 mmol, 2.5 equiv), α-ketone sulfoxonium ylides (0.4 mmol, 1.0 equiv),
Cs2CO3 (0.44 mmol, 1.1 equiv) in MeCN (0.8 mL).
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O
Pd2(dba)3 (5 mol %)
XPhos (20 mol %)
O
R
S
S
O
(Het)Ar-Br/OTf
O
(Het)Ar
Cs2CO3 (1.1 equiv)
MeCN (0.5 M), 80 °C, 16 h
R
13 26
–
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19
(X = H), 70%
O
S
O
O
S
O
O
S
O
(X = Me), 68%
(X = OMe), [51%]
(X = NO2), 90%
(X = CN), 74%
(X = CF3), 86%
(X = Cl), 69%
a
Ph
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Ph
S
F
F
X
N
20
, 69%
21
, 63%
O
S
O
O
S
O
O
S
O
O
S
O
H
Cy
Ph
Ph
X
O
Ph
22
, 96%
25
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, (R = 4-CN), 83%
, (R = 2-CN), 85%
O
b
23
, 54%
b
24
, 50%
Figure 2. Scope of (hetero)aryl bromides. Yields of pure isolated products from the reactions of
aryl bromides (1 mmol, 2.5 equiv), α-carbonyl sulfoxonium ylides (0.4 mmol, 1.0 equiv), Cs2CO3
(0.44 mmol, 1.1 equiv) in MeCN (0.8 mL). a 1H NMR yield. b From triflate.
Importantly, further optimization of the reaction conditions enabled us to decrease the loading of
aryl bromide and of XPhos. Decreasing the amount of aryl bromide is particularly relevant for the
late-stage modification of more precious material, as for example the antihistamine drug
bromazine.45 Cross-coupling product 27 could thus be obtained in 79% yield by using only 1.1
equivalent of bromazine and 11 mol % of XPhos (Scheme 2). Moreover, reducing the excess of
aryl bromide and XPhos is also relevant for gram-scale applications, as for example the reaction
of sulfoxonium ylide 28 with bromobenzene that gave 29 without decrease of the yield (Scheme
3). By using an iridium catalyst,31 this intermediate could then be converted in good yield into
piperidinone 30, a common precursor of L-733,060 and CP-99,994, two drugs developed as
antagonists of the neurokinin-1 receptor.46,47 It is noteworthy that the cyclization of 29 to give 30
is the first of its kind on a bis-substituted α-ketone-α’-(hetero)aryl sulfoxonium ylide.
Scheme 2. Late-stage modification of bromazine.
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Ph
O
O
S
Ph
S
Ph
O
Br
(1 equiv)
Pd2(dba)3 (5 mol %)
Ph
Ph
Ph
O
7
XPhos (11 mol %)
Cs2CO3 (1.1 equiv)
MeCN, 80 °C, 13 h
79%
8
9
O
NMe2
O
NMe2
27
2
2
bromazine
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(1.1 equiv)
Scheme 3. Gram-scale synthesis of a drug precursor.
PhBr
(1.5 equiv)
Pd2(dba)3 (5 mol %)
XPhos (11 mol %)
O
S
O
O
S
O
NHBoc
NHBoc
3
3
Cs2CO3 (1.1 equiv)
MeCN, 80 °C, 16 h
78% [gram scale]
Ph
29
28
[Ir(cod)Cl]2
(2.5 mol %)
1,2-DCE
80 °C, 10 h
73%
CF3
OMe
F3C
HN
O
O
Ph
N
Ph
N
Ph
N
H
H
Boc
CP-99,994
30
L-733,060
Study of the mechanism. To gain an insight into the mechanism of this reaction, we started our
study by preparing the known oxidative addition complex 31.48 We observed that this complex
was catalytically competent in the cross-coupling of 32 with bromobenzene (Scheme 4), and its
use actually led to a higher yield of product 33 as compared to what was obtained under the
conditions used to establish the scope described in figures 1 and 2. Importantly, the kinetic
competence of 31 was also established in the conversion of 32 into 33 and no difference of initial
rate was observed when compared to that obtained by using the combination of Pd2(dba)3 and
XPhos.
Scheme 4. Catalytic competence of oxidative addition complex 31.
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A or B, PhBr (2.5 equiv)
Cs2CO3 (1.1 equiv)
O
S
O
O
S
O
CF3
CF3
5
6
7
8
MeCN
80 °C, 14 h
Ph
33
CF3
CF3
Ph
32
A
B
Pd2(dba)3 (5 mol %)
XPhos (20 mol %)
73% conversion
31
(10 mol %)
XPhos (10 mol %)
89% conversion
9
Br
XPhos Pd
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31
31
Moreover, complex 31 was also observed by P NMR of the crude mixture resulting from the
coupling of ylide 34 and bromobenzene into product 13 (Figure 3). Thus, besides resonances for
XPhos and its oxide, we observed only a broad resonance at  = 27.2 ppm and a sharper one at 
= 55.6 ppm (Figure S1, Supporting Information) in an approximately equimolar ratio, which we
attribute to the monomer solvate complex [31•MeCN] and the solvent-free dimer
[(XPhos)PhPdBr]2, respectively. The attribution of these resonances is in a good agreement with
the findings recently reported by Hii and co-workers in their study of related mono-phosphines
complexes.49
PhBr
(2.5 equiv)
[(XPhos)PhPdBr•MeCN]
O
S
O
as in Figure 2
via
13
Br
Ph
34
18
Pd
p-CF3C6H4Br
(2.5 equiv)
as in Figure 2
XPhos
2
[observed by 31P NMR]
O
H
O
Ar
via
or
(Ar)(XPhos)Pd
(Ar)(XPhos)Pd
XPhos Pd Br
S
O
S
35
36
O
37
[observed by mass spectrometry]
31
Figure 3. Observation of a dimer of the oxidative addition intermediate by P NMR and
possible structures of transmetalation intermediates detected by mass spectrometry. Ar = p-
CF3C6H4.
Having established that the oxidative addition complexes [(XPhos)ArPdBr] are catalytically and
kinetically competent, we attempted to isolate a transmetalation complex that would result from
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the reaction of 31 and sulfoxonium ylides, but this endeavor remained unsuccessful. However, the
mass spectrum of the crude supernatant of the reaction between ylide 34 and p-CF3C6H4Br, carried
out under the catalytic conditions described in figure 2, showed minor peaks corresponding to a
transmetalation complex with the correct isotope distribution, which would correspond to either
35 ([35]+) or 36 ([36 + H]+) (Figure 4). The formation of such intermediates would be consistent
with an earlier report of a palladium complex resulting from the stoichiometric transmetalation of
Pd(II) salts with an α-ketone sulfoxonium ylide.50 Besides these minor peaks, the most abundant
peaks we could identity were those of the product 18 ([18 + H]+) and of a fragment of the oxidative
addition complex 37 ([37 – Br]+), as well as those of XPhos and its oxide (Figure S2, Supporting
Information). The interpretation of this data was confirmed by the independent synthesis of
complex 37 that was characterized by X-ray crystallography as a dimer in the solid state (Figure
4). Analysis of pure 37 by mass spectrometry gave the same molecular peaks corresponding to the
fragment [37– Br]+.
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Figure 4. Crystal structure of oxidative addition complex 37 in the solid state.
Scheme 5. Proposed mechanism.
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O
O
S
LPd(XPhos)
Pd(XPhos)
R
Ar Br
Ar
XPhos
Pd
Ar
Br
XPhos [Pd] Ar
Br
Pd
Br
Pd
R
S
Ar
Ar
XPhos
Br
XPhos
O
O
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II
IV
I
XPhos [Pd] Ar
R
S
Base
Base•HBr
O
O
S
O
O
III
R
In view of the data collected in our study, we propose a mechanism (Scheme 5), by which rapid
ligand exchange between dba and XPhos would generate an active catalyst (L = dba or MeCN).51
Then, oxidative addition would give intermediate I that is in equilibrium with an off-cycle inactive
dimer II, which is the resting state of the catalyst. We propose that I would undergo transmetalation
to III upon reaction with the ylide, which would be followed by deprotonation to give IV, whose
reductive elimination would regenerate the active catalyst and liberate the observed cross-coupling
products.
Further support for the proposed mechanism was obtained by determining the rate law of the
reaction conducted between model substrates p-CF3C6H4Br and sulfoxonium ylide 34. Varying
the initial concentrations of aryl bromide (0.30 – 1.25 M), ylide 34 (0.1 – 1.5 M), XPhos (0.06 –
0.50 M), and Pd2(dba)3 (0.006 – 0.038 M). We found that the initial rate (ratei) obeyed the equation
ratei = kobs[ylide]0.6[Pdtot]0.5, whereas the order in aryl bromide and ligand was zero. These results
confirmed several aspects of the mechanism of this reaction. First, the half-order in palladium is
consistent with an equilibrium between inactive dimer II and the kinetically and catalytically
competent oxidative addition intermediate I.52 Second, the partial order in ylide observed in the
rate law also suggests that the transmetalation is in the rate-determining zone of the catalytic
cycle.53 Third, the Lineweaver-Burk plots of the reciprocal of the initial rate as a function of the
reciprocal of the individual concentration of ylide (Figure 5) gave a good linear correlation with
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non-zero y intercept, which confirmed that one molecule of ylide is involved in the
transmetalation. Fourth, although Cs2CO3 is not soluble under the reaction conditions, we observed
a linear increase of the initial rate when increasing the amount of base from 0.44 to 2.0 equivalents
(See supporting information). This effect suggests that the deprotonation step should also be
included in the rate-determining zone, even if the order dependence in the concentration of base
could not be rigorously established.54
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Figure 5. Lineweaver-Burk plots of the reaction of model sulfoxonium ylide 34 and p-
CF3C6H4Br. 1/ratei = 56.8 ± 4.4 + (27.9 ± 0.9)/[34] (R2 = 0.99). Data from duplicate experiments.
Error bars omitted for clarity.
Overall, these results highlight a remarkable contrast between α-ketone sulfoxonium ylides and α-
diazoketones. Hence, our findings indicate that the transmetalation and deprotonation steps of the
palladium-catalyzed cross-couplings of aryl bromides with α-carbonyl sulfoxonium ylides are rate-
determining, whereas theoretical study of the palladium-catalyzed cross-coupling of α-diazo
ketones and aryl iodides suggested these two steps occurred without kinetic barrier.44 As
mentioned previously, it is noteworthy that the model α-carbonyl sulfoxonium ylide used in the
optimization of the reaction conditions was recovered unchanged when mixed with either
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iodobenzene or bromobenzene and treated under the conditions that catalyze the cross-coupling of
aryl iodides with α-diazo ketones,44 which could point to a less pronounced nucleophilic character
of sulfoxonium ylides as compared to their diazo counterpart in these reactions.
CONCLUSION
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In conclusion, we have reported a general palladium-catalyzed cross-coupling for the preparation
of α-carbonyl-α’-(hetero)aryl sulfoxonium ylides from easily available (hetero)aryl bromides and
triflates. The procedure shows excellent functional group tolerance and is amenable to the
modification of active pharmaceutical ingredients and to the synthesis of an advanced precursor
of drug candidates. We anticipate that the method of preparation of α-carbonyl-α’-(hetero)aryl
sulfoxonium ylides reported herein will enable the development of numerous reactions based on
these valuable and safe reagents. Finally, our findings suggest that the transmetallation of an
(hetero)aryl-palladium(II) intermediate by sulfoxonium ylides and the subsequent deprotonation
steps are rate-determining, in sharp contrast to comparable reactions of α-diazoketones.
EXPERIMENTAL SECTION
Otherwise noted, all reactions were carried out in flame-dried glassware under dry nitrogen
atmosphere. All commercially available reagents were used as received. THF was used after
passage through Innovative Technology PureSolv MD system. Acetonitrile was purchased as dry
solvent. Pd2(dba)3 was purchased from Strem. XPhos was purchased from FluoroChem: the
original container was stored in an argon-filled glovebox at room temperature and samples of
approximately 1 g were taken out of the glove box as needed and stored in a Schlenck tube that
was flushed with argon. Cesium carbonate (99.9%) was purchased from Sigma Aldrich. Flash
chromatography: Merck silica gel 60 (230-400 mesh). NMR: the 1H, 13C{1H}, and 31P{1H} spectra
were recorded on a Bruker DRX 500. The 19F{1H} spectra were recorded on a Bruker Avance 400
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spectrometer. chemical shifts (δ) are given in ppm. The solvent signals were used as references for
1H and 13C{1H} spectra (CDCl3: δ = 77.0; residual CHCl3 in CDCl3: δ = 7.26). The 31P{1H} spectra
were calibrated with an external standard (P(OPh)3, δ = 128.0 in CDCl3). The 19F{1H} spectra were
calibrated with an external standard ((trifluoromethyl)benzene, δ = -62.8). IR spectra were
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recorded on a PerkinElmer Spectrum 100 FT-IR spectrometer, and the wavenumbers (~ ) are given

in cm-1. HRMS determined at the University of Liverpool on Agilent 6540A Accurate-Mass Q-
ToF MS with Agilent Jetstream Source (ES+). Melting points were measured on a Griffin melting
point apparatus (not corrected).
Mono-substituted α-carbonyl sulfoxonium ylides (1, 28, 32, 34, 38–47). Compounds 1,9 28,30
34,9 38,8 39,8 40,55 41,39 42,9 43,8 44,33 45,1 and 4717 were prepared by the reported procedures.
1
The H NMR chemical shifts of these compounds were in agreement with the literature values.
Compounds 32 and 46 were prepared as described below.
O
S
O
O
S
O
O
S
O
N
OBn
N
38
39
40
O
O
O
S
O
O
O
S
S
Ph
NBoc
Ph
NHBoc
41
42
43
O
S
O
O
S
O
O
O
O
S
S
S
CHO
N
O
OMe
44
45
46
47
1-(3,5-Bis(trifluoromethyl)phenyl)-2-(dimethyl(oxo)-λ6-sulfaneylidene)ethan-1-one
(32).
Under nitrogen, trimethylsulfoxonium iodide (5.28 g, 24 mmol, 3.0 equiv) was suspended in dry
THF (50 mL) in a flame-dried round bottom flask that was protected from light with aluminium
foil. Potassium tert-butoxide (2.69 g, 24 mmol, 3.0 equiv) was added and the mixture was stirred
at reflux for 2 hours. After cooling to 0 °C, from 3,5-bis(trifluoromethyl)benzoyl chloride (5.4 mL,
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8.0 mmol, 1 equiv) in THF (16 mL) was added dropwise to the mixture via a dropping funnel.
After stirring at room temperature for 1 hour, the mixture was filtered through a plug of celite
(elution CH2Cl2). After evaporation of all volatiles, purification by flash chromatography (silica
gel, petroleum ether/ethyl acetate = 3:7 to 1:9) and recrystallization from ethyl acetate/hexane gave
compound 32 (7.86 g, 79%). White solid; m.p.: 152–154 °C. 1H NMR (500 MHz, CDCl3): δ 8.23
(s, 2H), 7.93 (s, 1H), 5.06 (s, 1H), 3.85 (s, 6H). 13C{1H} NMR (125 MHz, CDCl3): δ 178.2, 140.9,
131.6 (q, J = 33.3 Hz, 2C), 126.78, 126.75, 124.0 (hept, J = 3.7 Hz), 123.2 (q, J = 271.3 Hz, 2C),
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60
~
19
70.0, 42.2 (2C). F NMR (376 MHz, CDCl ): δ -62.9. IR (neat): = 3103 (w), 3025 (w), 3005

3
(w), 2921 (w), 1627 (w), 1548 (m), 1451 (w), 1406 (w), 1354 (m), 1311 (m), 1278 (s), 1191 (m),
1166 (s), 1132 (s), 1106 (s0, 1027 (s), 996 (m), 956 (m), 924 (w), 909 (m), 900 (m), 859 (m), 844
(m), 767 (w), 753 (w), 698 (w), 682 (w), 670 (w). HRMS (ESI): m/z calcd for C12H11F6O2S [M +
H]+: 333.0378; found: 333.0382.
2-(Dimethyl(oxo)-λ6-sulfaneylidene)-1-(5-methylisoxazol-3-yl)ethan-1-one
(46).
This
compound (259 mg, 38%, white solid) was obtained from 5-methylisoxazole-3-carbonyl chloride
(0.49 g, 3.4 mmol, 1 equiv) according to the method described for the preparation of 32 and after
purification by flash chromatography (silica gel, CH2Cl2/MeOH = 98:2): 259 mg, 38%. White
1
solid; m.p.: 117–119 °C. H NMR (500 MHz, CDCl3): δ 6.30 (q, J = 0.9 Hz, 1H), 5.33 (s, 1H),
3.50 (s, 6H), 2.43 (d, J = 0.9 Hz, 3H). 13C{1H} NMR (125 MHz, CDCl3): δ 173.4, 170.0, 163.1,
~
100.3, 70.7, 42.1, 12.3. IR (neat): = 3140 (w), 3097 (w), 3009 (w), 2922 (w), 1599 (w), 1547 (s),

1465 (w), 1449 (s), 1344 (s), 1318 (w), 1295 (w), 1245 (w), 1182 (s), 1133 (w), 1073 (w), 1020
(s), 1008 (m), 996 (m), 979 (m), 941 (w), 901 (m), 848 (s), 827 (m), 813 (w), 768 (w), 753 (w),
689 (w), 658 (w). HRMS (ESI): m/z calcd for C8H12NO3S [M + H]+: 202.0532; found: 202.0530.
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Representative procedure for the palladium-catalyzed cross-coupling of α-carbonyl
sulfoxonium ylides. Under nitrogen, a J-Young Schlenck tube was charged with XPhos (38 mg,
0.08 mmol, 0.2 equiv), Pd2dba3 (18 mg, 0.02 mmol, 0.05 equiv) and Cs2CO3 (143.4 mg, 0.44
mmol, 1.1 equiv). Acetonitrile (0.4 mL) was then added and the mixture was stirred at room
temperature for 10 minutes. Then, bromobenzene (160 μL, 2.5 mmol, 2.5 equiv) was added
followed by sulfoxonium ylide 1 (87 mg, 0.4 mmol, 1 equiv). The inner wall of the Schlenck tube
was rinsed with acetonitrile (0.4 mL) and the tube was then sealed, placed in a preheated oil bath
set at 80 °C and stirred for 15 hours. The crude was then filtered over celite at room temperature
using dichloromethane to transfer all the material and for rinsing. After evaporation of all volatiles
under vacuum, purification by flash chromatography (silica gel; ethyl acetate/methanol: 9:1)
afforded compound 2 (97 mg, 83%).
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3-Cyclohexyl-1-(dimethyl(oxo)-λ6-sulfaneylidene)-1-phenylpropan-2-one (2). Off-white solid;
m.p.: 109-112 °C. 1H NMR (500 MHz, CDCl3): δ 7.36-7.27 (m, 3H), 7.25-7.21 (m, 2H), 3.47 (s,
6H), 2.01 (d, J = 7.3 Hz, 2H), 1.84-1.71 (m, 1H), 1.67-1.52 (m, 5H), 1.27-1.14 (m, 2H), 1.11-0.97
(m, 1H), 0.77 (q, J = 13.3 Hz, 2H). 13C{1H} NMR (125 MHz, CDCl3): δ 188.6, 134.8 (2C), 132.1,
~
128.4, (2C), 127.7, 86.7, 45.4, 43.1 (2C), 35.2, 33.2 (2C), 26.3, 26.2 (2C). IR (neat): = 3675 (w),

3063 (w), 3014 (w), 2943 (w), 2916 (m), 2848 (w), 1534 (s), 1490 (w), 1439 (w), 1375 (s), 1312
(w), 1294 (w), 1272 (w), 1225 (m), 1182 (s), 1112 (w), 1073 (w), 1007 (m), 994 (m), 965 (m), 939
(m), 916 (w), 888 (w), 848 (w), 795 (w), 760 (w), 742 (m), 701 (s); HRMS (ESI): m/z calcd for
C17H25O2S [M + H]+: 293.1570; found: 293.1578.
4-(1-(Dimethyl(oxo)-λ6-sulfaneylidene)-4-(1-methyl-1H-indol-3-yl)-2-oxobutyl)benzonitrile
(3). Obtained from 38 (111 mg, 0.4 mmol, 1 equiv) and 4-bromobenzonitrile (182 mg, 1.0 mmol,
2.5 equiv) following the representative procedure and after purification by flash chromatography
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(silica gel; ethyl acetate/methanol = 9:1): 135 mg, 89%. Off-white solid; m.p.: 127–130 °C. H
NMR (500 MHz, CDCl3): δ 7.43 (dt, J = 8.3, 2.1 Hz, 2H), 7.39 (d, J = 7.8 Hz, 1H), 7.25 (d, J =
8.2 Hz, 1H), 7.19 (dd, J = 6.9, 0.8 Hz, 1H), 7.05-7.00 (m, 3H), 6.70 (s, 1H), 3.68 (s, 3H), 3.44 (s,
6H), 3.02 (t, J = 7.4 Hz, 2H), 2.56 (t, J = 7.4 Hz, 2H). 13C{1H} NMR (125 MHz, CDCl3): δ 188.0,
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137.0, 136.6, 134.1 (2C), 131.4 (2C), 127.5, 126.0, 121.3, 118.7, 118.7, 188.3, 113.9, 109.9, 108.9,
~
85.0, 43.1 (2C), 38.9, 32.3, 21.2. IR (neat): = 3082 (w), 3038 (w), 3013 (w), 2967 (w), 2926 (w),

2855 (w), 2226 (m), 1600 (w), 1560 (s), 1497 (w), 1485 (w), 1474 (w), 1450 (w), 1434 (w), 1419
(w), 1395 (w), 1377 (w), 1343 (m), 1329 (m), 1321 (m), 1279 (w), 1264 (w), 1248 (w), 1223 (m),
1205 (m), 1172 (s), 1119 (w), 1065 (m), 1036 (m), 1008 (w), 976 (w), 934 (m), 915 (w), 847 (w),
800 (w), 748 (s), 735 (m), 697 (m), 656 (w). HRMS (ESI): m/z calcd for C22H23N2O2S [M + H]+:
379.1475; found: 379.1479.
4-(1-(Dimethyl(oxo)-λ6-sulfaneylidene)-2-oxo-3-(1H-pyrrol-1-yl)propyl)benzonitrile
(4).
Obtained from 39 (80 mg, 0.4 mmol, 1 equiv) and 4-bromobenzonitrile (182 mg, 1.0 mmol, 2.5
equiv) following the representative procedure and after purification by flash chromatography
(silica gel; ethyl acetate/methanol = 97:3 to 93:7): 95 mg, 79%. Light-brown solid; m.p: 123–125
°C. 1H NMR (500 MHz, CDCl3): δ 7.64 (d, J = 8.2 Hz, 2H), 7.34 (d, J = 8.3 Hz, 2H), 6.52 (t, J =
2.1 Hz, 2H), 6.11 (t, J = 2.1 Hz, 2H), 4.46 (s, 2H), 3.51 (s, 6H). 13C{1H} NMR (125 MHz, CDCl3):
δ 180.9, 135.6, 134.4 (2C), 132.1 (2C), 121.4 (2C), 118.5, 111.2, 108.3 (2C), 83.9, 54.2, 42.9 (2C);
~
IR (neat): = 3094 (w), 3012 (w), 2915 (w), 2228 (m), 1603 (w), 1541 (s), 1500 (m), 1432 (w),

1391 (w), 1382 (w), 1329 (w), 1296 (w), 1280 (w), 1226 (w), 1195 (s), 1183 (s), 1116 (w), 1095
(w), 1070 (w), 1056 (w), 1013 (m), 986 (w), 969 (m), 955 (M), 932 (w), 908 (w), 888 (w), 847
(w), 836 (w), 807 (w), 774 (w), 731 (s), 738 (s), 688 (w), 654 (w). HRMS (ESI): m/z calcd for
C16H16N2NaO2S [M + Na]+: 323.0825; found: 323.0823.
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4-(3-(Benzyloxy)-1-(dimethyl(oxo)-λ6-sulfaneylidene)-2-oxopropyl)benzonitrile (5). Obtained
from 40 (96 mg, 0.4 mmol, 1 equiv) and 4-bromobenzonitrile (182 mg, 1.0 mmol, 2.5 equiv)
following the representative procedure and after purification by flash chromatography (silica gel;
ethyl acetate/methanol = 9:1): 112 mg, 82%. Orange oil. 1H NMR (500 MHz, CDCl3): δ 7.56 (dt,
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13
J = 8.4, 1.9 Hz, 2H), 7.35-7.21 (m, 7H), 4.52 (s, 2H), 4.00 (s, 2H), 3.57 (s, 6H). C{1H} NMR
(125 MHz, CDCl3): δ 183.2, 137.4, 135.8, 133.8 (o, 2C), 131.6 (o, 2C), 128.1 (o, 2C), 127.7 (o,
~
2C), 127.5 (o), 118.6 (e), 110.4 (e), 84.1 (e), 73.1 (e), 71.8 (e), 42.9 (o, 2C). IR (neat): = 3006

(w), 2919 (w), 2858 (w), 2224 (m), 1542 (s), 1499 (m), 1454 (w), 1404 (m), 1328 (m), 1307 (m),
1198 (s), 1179 (s), 1104 (s), 1020 (s), 970 (m), 942 (w), 912 (w), 837 (w), 734 (s), 699 (m), 683
(w). HRMS (ESI): m/z calcd for C19H20NO3S [M + H]+: 342.1158; found: 342.1165.
Tert-butyl
(4-(4-cyanophenyl)-4-(dimethyl(oxo)-λ6-sulfaneylidene)-3-oxobutan-2-
yl)carbamate (6). Obtained from racemic 41 (105 mg, 0.4 mmol, 1 equiv) and 4-
bromobenzonitrile (182 mg, 1.0 mmol, 2.5 equiv) following the representative procedure and after
purification by flash chromatography (silica gel; ethyl acetate/methanol = 95:5 to 92:8): 127 mg,
1
87%. Yellow solid; m.p.: 130-133 °C. H NMR (500 MHz, CDCl3): δ 7.57 (d, J = 8.2 Hz, 2H),
7.39 (d, J = 7.9 Hz, 2H), 5.28 (d, J = 7.3 Hz, 1H), 4.29 (q, J = 7.3 Hz, 1H), 3.53 (s, 3H), 3.42 (s,
3H), 1.35 (s, 9H), 1.00 (d, J = 6.9 Hz, 3H); 13C{1H} NMR (125 MHz, CDCl3): δ 186.5 (e), 154.8
(e), 135.9 (e), 134.6 (o, 2C), 132.0 (o, 2C), 118.6 (e), 110.9 (e), 83.1 (e), 78.9 (e), 49.5 (o), 42.9
~
(o), 42.8 (o), 28.2 (o, 3C), 19.3 (o); IR (neat): = 3245 (m, br), 2934 (m), 2934 (w), 2227 (m),

1685 (s), 1603 (w), 1536 (s), 1452 (w), 1391 (m), 1365 (m), 1337 (w), 1311 (w), 1296 (m), 1280
(m), 1253 (m), 1213 (m), 1199 (s), 1165 (s), 1107 (m), 1058 (m), 1011 (s), 963 (m), 943 (m), 880
(w), 852 (w), 792 (w), 744 (m), 681 (m). HRMS (ESI): m/z calcd for C18H25N2O4S [M + H]+:
365.1530; found: 365.1532.
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Tert-butyl
4-(2-(4-cyanophenyl)-2-(dimethyl(oxo)-λ6-sulfaneylidene)acetyl)piperidine-1-
5
6
7
8
carboxylate (7). Obtained from 42 (121 mg, 0.4 mmol, 1 equiv) and 4-bromobenzonitrile (182
mg, 1.0 mmol, 2.5 equiv) following the representative procedure (after purification by flash
chromatography (ethyl acetate/methanol = 95:5 to 92:8): 138 mg, 85%. Off-white solid; m.p.: 154–
156 °C. 1H NMR (500 MHz, CDCl3): δ 7.59 (d, J = 8.5 Hz, 2H), 7.30 (d, J = 8.3 Hz, 2H), 4.01 (br
s, 2H), 3.49 (s, 6H), 2.57-2.36 (m, 3H), 1.60 (qd, J = 12.8, 4.4 Hz, 2H), 1.53-1.42 (m, 2H), 1.38
(s, 9H). 13C{1H} NMR (125 MHz, CDCl3): δ 189.9, 154.5, 136.8, 134.3 (2C), 131.9 (2C), 118.6,
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110.7, 84.1, 79.2, 43.4 (2C), 43.1 (2C, not visible but inferred from HSQC), 42.8, 28.4 (2C), 28.3
~
(3C); IR (neat): = 3667 (w), 3008 (w), 2976 (w), 2919 (w), 2855 (w), 2228 (m), 1673 (s), 1601

(w), 1571 (w), 1540 (s), 1499 (w), 1477 (w), 1466 (w), 1431 (m), 1388 (m), 1364 (w), 1349 (w),
1304 (w), 1273 (w), 1242 (w), 1192 (s), 1159 (s), 1125 (m), 1068 (w), 1031 (s), 989 (w), 965 (m),
945 (w), 928 (w), 865 (w), 845 (w), 812 (w), 756 (w), 727 (s), 680 (w). HRMS (ESI): m/z calcd
for C21H29N2O4S [M + H]+: 405.1843; found: 405.1849.
4-(1-(Dimethyl(oxo)-λ6-sulfaneylidene)-2-oxo-3,3-diphenylpropyl)benzonitrile (8). Obtained
from 43 (115 mg, 0.4 mmol, 1 equiv) and 4-bromobenzonitrile (182 mg, 1.0 mmol, 2.5 equiv)
following the representative procedure and after purification by flash chromatography (silica gel;
petroleum ether/ethyl acetate = 1:4): 138 mg, 89%. Pale-orange solid; m.p.: 99–102 °C. 1H NMR
(500 MHz, CDCl3): δ 7.56 (d, J = 7.6 Hz, 2H), 7.30-7.16 (m, 12H), 5.01 (s, 1H), 3.49 (s, 6H).
13C{1H} NMR (125 MHz, CDCl3): δ 185.9, 140.5 (2C), 136.7, 134.7 (2C), 131.7 (2C), 128.6 (4C),
~
128.2 (4C), 126.4 (2C), 118.6, 110.8, 85.5, 57.7, 43.0 (2C). IR (neat): = 3674 (w), 3083 (w),

3060 (w), 3029 (w), 3008 (w), 2913 (w), 2221 (m), 1755 (w), 1718 (w), 1673 (w), 1600 (m), 1539
(s), 1495 (m), 1448 (w), 1397 (w), 1371 (m), 1302 (m), 1272 (w), 1198 (s), 1180 (m), 1110 (w),
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1077 (w), 10323 (w), 1014 (m), 970 (m), 957 (w), 935 (m), 877 (w), 836 (m), 782 (w), 734 (s),
5
6
704 (s), 681 (m). HRMS (ESI): m/z calcd for C24H22NO2S [M + H]+: 388.1366; found: 388.1363.
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8
9
4-(2-(3,5-Bis(trifluoromethyl)phenyl)-1-(dimethyl(oxo)-λ6-sulfaneylidene)-2-
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11
12
13
14
15
16
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18
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oxoethyl)benzonitrile (9). Obtained from 32 (132 mg, 0.4 mmol, 1 equiv) and 4-
bromobenzonitrile (182 mg, 1.0 mmol, 2.5 equiv) following the representative procedure and after
purification by flash chromatography (silica gel; petroleum ether/ethyl acetate = 6:4 to 3:7): 142
mg, 82%. Yellow solid; m.p.: 91–94 °C; 1H NMR (500 MHz, CDCl3): δ 7.73 (s, 3H), 7.47 (d, J =
8.1 Hz, 2H), 7.18 (d, J = 8.1 Hz, 2H), 3.67 (s, 6H). 13C NMR (125 MHz, CDCl3): δ 179.1, 141.4,
136.4, 134.3 (2C), 131.8 (2C), 131.0 (q, J = 34.0 Hz, 2C), 128.9* (q, J = 2.6 Hz), 123.1 (sept, J =
3.7 Hz, 2C), 121.7 (q, J = 273.2 Hz, 2C), 118.5, 110.6, 86.8, 42.8 (2C) (the signal marked by an
asterisk is an unresolved quartet; the coupling constant was determined from the two central
~
resonances). 19F{1H} NMR (376 MHz, CDCl ): δ -63.2. IR (neat): = 3675 (w), 3075 (w), 3004

3
(w), 2989 (w), 2918 (w), 2223 (m), 1624 (w), 1602 (w), 1538 (s), 1505 (m), 1444 (w), 1407 (w),
1389 (w), 1349 (m), 1275 (s), 1240 (m), 1211 (m), 1196 (m), 1169 (s), 1112 (s), 1027 (s), 991 (w),
968 (w), 944 (w), 922 (w), 891 (s), 844 (m), 835 (m), 754 (m), 729 (m), 698 (m), 678 (s). HRMS
(ESI): m/z calcd for C19H14F6NO2S [M + H]+: 434.0644; found: 434.0644.
4-(1-(Dimethyl(oxo)-λ6-sulfaneylidene)-2-(4-methoxyphenyl)-2-oxoethyl)benzonitrile (10).
Obtained from 44 (91 mg, 0.4 mmol, 1 equiv) and 4-bromobenzonitrile (182 mg, 1.0 mmol, 2.5
equiv) following the representative procedure and after purification by flash chromatography
(silica gel; ethyl acetate/methanol = 95:5 to 90:10): 105 mg, 80%. Yellow solid; m.p.: 149–152
°C. 1H NMR (500 MHz, CDCl3): δ 7.40 (d, J = 8.5 Hz, 2H), 7.24 (d, J = 8.7 Hz, 2H), 7.18 (d, J =
8.5 Hz, 2H), 6.65 (d, J = 8.8 Hz, 2H), 3.71 (s, 3H), 3.60 (s, 6H). 13C{1H} NMR (125 MHz, CDCl3):
δ 183.1, 160.8, 138.0, 133.9 (2C), 131.8, 131.3 (2C), 130.4 (2C), 119.0, 112.8 (2C), 109.2, 84.5,
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55.0, 43.3 (2C). IR (neat): = 2991 (w), 2914 (w), 2839 (w), 2228 (s), 1601 (m), 1579 (m), 1505

5
6
7
8
(s), 1494 (s), 1463 (w), 1374 (s), 1303 (m), 1250 (s), 1187 (s), 1171 (s), 1119 (w), 1016 (s), 984
(w), 967 (w), 954 (m), 942 (m), 861 (w), 844 (s), 818 (m), 781 (w), 770 (w), 757 (s), 728 (m), 689
(w), 675 (w). HRMS (ESI): m/z calcd for C18H18NO3S [M + H]+: 328.1002; found: 328.1007.
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10
11
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14
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4-(1-(Dimethyl(oxo)-λ6-sulfaneylidene)-2-oxo-2-(thiophen-2-yl)ethyl)benzonitrile
(11).
Obtained from 45 (81 mg, 0.4 mmol, 1 equiv) and 4-bromobenzonitrile (182 mg, 1.0 mmol, 2.5
equiv) following the representative procedure and after purification by flash chromatography
(silica gel, ethyl acetate to ethyl acetate/methanol = 95:5): 95 mg, 82%. Off-white solid; m.p.: 201–
203 °C. 1H NMR (500 MHz, CDCl3): δ 7.62-7.57 (m, 2H), 7.44-7.40 (m ,2H), 7.32 (dd, J = 5.0,
1.1 Hz, 1H), 6.81 (dd, J = 5.0, 3.8 Hz, 1H), 6.66 (dd, J = 3.8, 1.0 Hz, 1H), 3.65 (s, 6H). 13C{1H}
NMR (125 MHz, CDCl3): δ 174.4, 144.8, 136.7, 135.5 (2C), 132.0 (2C), 129.6, 129.3, 127.1,
~
118.8, 111.3, 83.9, 43.6 (2C). IR (neat): = 3112 (w), 3069 (w), 3023 (w), 2999 (m), 2914 (w),

2220 (m), 1601 (w), 1518 (m), 1504 (s), 1492 (s), 1415 (m), 1405 (m), 1380 (s), 1347 (w), 1306
(w), 1289 (w), 1251 (m), 1230 (w), 1191 (s), 1180 (s), 1108 (w), 1092 (m), 1071 (w), 1044 (w),
1020 (s), 980 (m), 962 (m), 947 (s), 868 (w), 846 (m), 831 (w), 763 (m), 741 (m), 718 (s), 674 (m),
664 (m). HRMS (ESI): m/z calcd for C15H14NO2S2 [M + H]+: 304.0460; found: 304.0495.
4-(1-(Dimethyl(oxo)-λ6-sulfaneylidene)-2-(5-methylisoxazol-3-yl)-2-oxoethyl)benzonitrile
(12). Obtained from 46 (80 mg, 0.4 mmol, 1 equiv) and 4-bromobenzonitrile (182 mg, 1.0 mmol,
2.5 equiv) following the representative procedure and after purification by flash chromatography
(silica gel, ethyl acetate/methanol = 95:5 to 92:8): 100 mg, 83%. Beige solid; m.p.: 162–165 °C.
1H NMR (500 MHz, CDCl3): δ 7.53 (dt, J = 8.5, 1.8 Hz, 2H), 7.32 (dt, J = 8.5, 1.8 Hz, 2H), 5.90
(s, 1H), 3.66 (s, 6H), 2.33 (s, 3H). 13C{1H} NMR (125 MHz, CDCl3): δ 172.2, 169.0, 162.3, 135.6,
~
134.4 (2C), 131.4 (2C), 118.7, 110.6, 101.1, 88.1, 42.5 (2C), 11.9. IR (neat): = 3122 (w), 2995

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(w), 2914 (w), 2227 (m), 1601 (m), 1526 (s), 1444 (m), 1406 (m), 1348 (m), 1308 (m), 1274 (w),
1260 (m), 1992 (s), 1108 (w), 1017 (s), 986 (w), 961 (m), 943 (s), 920 (w), 900 (m), 846 (m), 792
(w), 765 (m), 738 (w), 727 (w), 681 (m), 657 (w). HRMS (ESI): m/z calcd for C15H14N2NaO3S [M
+ Na]+: 325.0617; found: 325.0622.
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1-(Dimethyl(oxo)-λ6-sulfaneylidene)-1-phenylpropan-2-one (13). Obtained from 34 (134 mg,
1.0 mmol, 1 equiv) and bromobenzene (160 μL, 2.5 mmol, 2.5 equiv) following the representative
procedure and after purification by flash chromatography on a short pad of silica gel (ethyl
acetate/methanol = 90:10 to 87:13): 147 mg, 70%. Amorphous solid. 1H NMR (500 MHz, CDCl3):
δ 7.42-7.25 (m, 5H), 3.49 (s, 6H), 1.90 (s, 3H). 13C{1H} NMR (125 MHz, CDCl3): δ 186.4, 134.3
~
(2C), 132.5, 128.4 (2C), 127.7, 85.8, 42.9 (2C), 26.5. IR (neat): = 3393 (w), 3013 (m), 2921 (m),

1532 (s), 1489 (m), 1410 (w), 1366 (s), 1308 (w), 1234 (s), 1166 (s), 1023 (s), 1001 (s), 967 (m),
939 (w), 914 (w), 850 (w), 804 (w), 760 (m), 738 (w), 702 (s), 661 (w), 654 (w). HRMS (ESI):
m/z calcd for C11H15O2S [M + H]+: 211.0787; found: 211.0790.
1-(Dimethyl(oxo)-λ6-sulfaneylidene)-1-(p-tolyl)propan-2-one (14). Obtained from 34 (54 mg,
0.4 mmol, 1 equiv) and 4-bromotoluene (123 μL, 1.0 mmol, 2.5 equiv) following the representative
procedure and after purification by flash chromatography on a short pad of silica gel (ethyl
acetate/methanol = 90:10 to 86:14): 62 mg, 69%. Amorphous solid. 1H NMR (500 MHz, CDCl3):
δ 7.14 (apparent broad s, 4H), 3.46 (s, 6H), 2.35 (s, 3H), 1.88 (s, 3H). 13C{1H} NMR (125 MHz,
~
CDCl ): δ 186.5, 137.6, 134.2 (2C), 129.4, 129.3 (2C), 85.4, 42.8 (2C), 26.5, 21.1; IR (neat):
=

3
3350 (m), 3018 (m), 2920 (m), 2232 (w), 1536 (s), 1509 (m), 1406 (m), 1366 (s), 1306 (w), 1234
(s), 1165 (s), 1107 (w), 1024 (s), 970 (m), 940 (w), 923 (w), 814 (m), 794 (w), 722 (s), 695 (m).
HRMS (ESI): m/z calcd for C12H17O2S [M + H]+: 225.0944; found: 225.0947.
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1-(Dimethyl(oxo)-λ6-sulfaneylidene)-1-(4-methoxyphenyl)propan-2-one (15). This compound
was obtained from 34 (54 mg, 0.4 mmol, 1 equiv) and 4-bromo-anisole (125 μL, 1.0 mmol, 2.5
equiv) following the representative procedure. The compound underwent degradation under the
reaction conditions but the maximal yield reached 51% after 2 hours of reaction as judged by 1H
NMR with internal standard (1,3,5-trimethoxybenzene). Attempted purification by flash
chromatography on a short pad of silica gel (ethyl acetate/methanol = 4:1 to 1:1) gave 26% of the
compound contaminated by some remaining starting material 34 (5%) and DMSO (1%). Only the
resonances corresponding to 15 are described herein. 1H NMR (500 MHz, CDCl3): δ 7.17 (dt, J =
8.7, 2.1 Hz 2H), 6.88 (dt, J = 8.7, 2.1 Hz, 2H), 3.81 (s, 3H), 3.46 (s, 6H), 1.87 (s, 3H); 13C NMR
(125 MHz, CDCl3): δ 186.8, 159.3, 135.7 (2C), 124.5, 113.4 (2C), 85.0, 55.2, 42.8 (2C), 26.5.
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1-(Dimethyl(oxo)-λ6-sulfaneylidene)-1-(4-nitrophenyl)propan-2-one (16). Obtained from 34
(54 mg, 0.4 mmol, 1 equiv) and 1-bromo-4-nitrobenzene (202 mg, 1.0 mmol, 2.5 equiv) following
the representative procedure and after purification by flash chromatography (silica gel, ethyl
1
acetate/methanol = 95:5 to 90:10): 92 mg, 90%. Yellow solid; m.p.: 135-140 °C. H NMR (500
MHz, CDCl3): δ 8.13 (dt, J = 8.9, 2.1 Hz, 2H), 7.36 (dt, J = 8.9, 2.1 Hz, 2H), 3.56 (s, 6H), 1.98 (s,
3H); 13C{1H} NMR (125 MHz, CDCl3): δ 186.0, 146.0, 139.8, 133.5 (2C), 123.1 (2C), 84.6 (e),
~
43.5 (2C), 26.5. IR (neat): = 3066 (w), 3022 (w), 3000 (w), 2916 (m), 2436 (w), 1586 (m), 1526

(s), 1508 (s), 1437 (w), 1405 (w), 1363 (m), 1346 (m), 1324 (s), 1307 (m), 1245 (m), 1194 (s),
1108 (s). HRMS (ESI): m/z calcd for C11H14NO4S [M + H]+: 256.0638; found: 256.0644.
4-(1-(Dimethyl(oxo)-λ6-sulfaneylidene)-2-oxopropyl)benzonitrile (17). Obtained from 34 (54
mg, 0.4 mmol, 1 equiv) and 4-bromobenzonitrile (182 mg, 1.0 mmol, 2.5 equiv) following the
representative procedure and after purification by flash chromatography (silica gel, ethyl
1
acetate/methanol = 95:5 to 85:15): 70 mg, 74%. Yellow solid; m.p.: 106-109 °C. H NMR (500
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MHz, CDCl3): δ 7.55 (d, J = 8.4 Hz, 2H), 7.30 (d, J = 8.5 Hz, 2H), 3.51 (s, 6H), 1.92 (s, 3H).
5
6
13C{1H} NMR (125 MHz, CDCl3): δ 185.8, 137.6, 133.8 (2C), 131.7 (2C), 118.8, 110.0, 84.7, 43.3
7
8
9
~
(2C), 26.4. IR (neat): = 3411 (w), 3054 (w), 3016 (m), 2995 (m), 2910 (m), 2227 (s), 1601 (m),

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13
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1521 (s), 1403 (w), 1376 (s), 1348 (w), 1310 (m), 1267 (w), 1242 (m), 1200 (s), 1114 (w), 1033
(s), 1011 (m), 985 (w), 968 (s), 949 (s), 917 (w), 865 (w), 850 (m), 840 (m), 777 (m), 732 (s), 685
(s). HRMS (ESI): m/z calcd for C12H14NO2S [M + H]+: 236.0740; found: 236.0742.
1-(Dimethyl(oxo)-λ6-sulfaneylidene)-1-(4-(trifluoromethyl)phenyl)propan-2-one
(18).
Obtained from 34 (54 mg, 0.4 mmol, 1 equiv) and 4-bromobenzotrifluoride (140 μL, 1.0 mmol,
2.5 equiv) following the representative procedure) and after purification by flash chromatography
1
(silica gel, ethyl acetate/methanol = 9:1): 96 mg, 86. Off-white amorphous solid. H NMR (500
MHz, CDCl3): δ 7.54 (d, J = 8.2 Hz, 2H), 7.33 (d, J = 8.1 Hz, 2H), 3.48 (s, 6H), 1.89 (s, 3H).
13C{1H} NMR (125 MHz, CDCl3): δ 186.0, 136.3, 134.0 (2C), 128.9 (q, J = 32.0 Hz), 125.0 (q, J
= 3.5 Hz, 2C) 124.1 (q, J = 272.0 Hz), 84.5, 43.1 (2C), 26.4 (o). 19F{1H} NMR (376 MHz, CDCl3):
~
δ -62.4. IR (neat): = 3025 (w), 2925 (w), 1609 (w), 1538 (s), 1403 (w), 1376 (m), 1322 (s), 1241

(m), 1177 (s), 1110 (s), 1067 (s), 1019 (m), 1005 (m), 983 (w), 972 (w), 946 (w), 835 (s), 777 (w),
735 (m), 701 (m), 664 (w). HRMS (ESI): m/z calcd for C12H14F3O2S [M + H]+: 279.0661; found:
279.0667.
1-(4-Chlorophenyl)-1-(dimethyl(oxo)-λ6-sulfaneylidene)propan-2-one (19). Obtained from 34
(54 mg, 0.4 mmol, 1 equiv) and 1-bromo-4-chlorobenzene (192 mg, 1.0 mmol, 2.5 equiv)
following the representative procedure and after purification by flash chromatography (silica gel,
ethyl acetate/methanol = 95:5 to 85:15): 68 mg, 69%. Yellow solid; m.p.: 111–114 °C. 1H NMR
(500 MHz, CDCl3): δ 7.28 (dt, J = 8.5, 2.5 Hz, 2H), 7.16 (dt, J = 8.6, 2.1 Hz, 2H), 3.46 (s, 6H),
13
1.86 (s, 3H). C{1H} NMR (125 MHz, CDCl3): δ 186.1, 135.4 (2C), 133.6, 130.8, 128.5 (2C),
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84.2, 42.9 (2C), 26.4. IR (neat): = 3050 (w), 3030 (w), 3014 (m), 2998 (w), 2929 (m), 1587 (w),

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6
7
8
1552 (s), 1488 (m), 1421 (w), 1395 (w), 1361 (s), 1343 (m), 1322 (w), 1259 (w), 1235 (s), 1177
(w), 1156 (s), 1101 (w), 1086 (m), 1057 (w), 1033 (s), 1012 (s), 989 (m), 979 (s), 924 (m), 911
(m), 842 (m), 818 (m), 752 (m), 730 (w), 718 (m), 689 (m). HRMS (ESI): m/z calcd for
C11H14ClO2S [M + H]+: 245.0398; found: 245.0402.
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1-(3,5-Difluorophenyl)-1-(dimethyl(oxo)-λ6-sulfaneylidene)propan-2-one (20). Obtained from
34 (54 mg, 0.4 mmol, 1 equiv) and 1-bromo-3,5-difluorobenzene (110 µL, 1.0 mmol, 2.5 equiv)
following the representative procedure and after purification by flash chromatography (silica gel,
ethyl acetate/methanol = 95:5 to 90:10): 68 mg, 69%. Yellow solid; m.p.: 134–136 °C. 1H NMR
13
(500 MHz, CDCl3): δ 6.82–6.70 (m, 3H), 3.51 (s, 6H), 1.93 (s, 3H). C{1H} NMR (125 MHz,
CDCl3): δ 186.1, 163.4 (d, J = 13.6 Hz, 2C), 161.5 (d, J = 13.6 Hz), 135.6 (t, J = 10.0 Hz), 116.7
(dd, J = 19.0, 5.8 Hz, 2C), 103.0 (t, J = 25.4 Hz), 43.2 (2C), 26.5 (o); 19F{1H} NMR (125 MHz,
~
CDCl ): δ -110.6. IR (neat): = 3675 (w), 3063 (w), 3014 (w), 2943 (w), 2916 (m), 2848 (w),

3
1534 (s), 1490 (w), 1439 (w), 1375 (s), 1312 (w), 1294 (w), 1272 (w), 1225 (m), 1182 (s), 1112
(w), 1073 (w), 1007 (m), 994 (m), 965 (m), 939 (m), 916 (w), 888 (w), 848 (w), 795 (w), 760 (w),
742 (m), 701 (s). HRMS (ESI): m/z calcd for C11H13F2O2S [M + H]+: 247.0608; found: 247.0599.
1-(Dimethyl(oxo)-λ6-sulfaneylidene)-3,3-diphenyl-1-(thiophen-3-yl)propan-2-one
(21).
Obtained from 43 (115 mg, 0.4 mmol, 1 equiv) and 3-bromothiophene (94 μL, 1.0 mmol, 2.5
equiv) following the representative procedure and after purification by flash chromatography
(silica gel, hexane/ethyl acetate = 1:1 to 1:4): 92 mg, 63%. Off-white solid; m.p.: 118–120 °C. 1H
NMR (500 MHz, CDCl3): δ 7.32–7.16 (m, 11H), 7.03 (dd, J = 2.9, 1.0 Hz, 1H), 6.83 (dd, J = 4.8,
13
0.9 Hz, 1H), 5.03 (s, 1H), 3.40 (s, 6H). C{1H} NMR (125 MHz, CDCl3): δ 187.0, 141.3 (2C),
~
132.5, 131.0, 129.3, 129.0 (4C), 128.3 (4C), 126.4 (2C), 125.2, 80.6, 57.9, 42.5 (2C). IR (neat):

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= 3081 (w), 3060 (w), 3026 (w), 2929 (w), 1753 (w), 1716 (w), 1656 (w), 1560 (s), 1492 (m),
1447 (w), 1392 (w), 1344 (m), 1315 (w), 1304 (w), 1248 (w), 1210 (w), 1168 (s) 1155 (s), 1076
(w), 1028 (s), 953 (w), 927 (w), 904 (w), 876 (w), 850 (m), 807 (m), 783 (w), 752 (w), 736 (m),
714 (s), 699 (s), 683 (s). HRMS (ESI): m/z calcd for C21H21O2S2 [M + H]+: 369.0977; found:
369.0978.
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1-(Dimethyl(oxo)-λ6-sulfaneylidene)-1-(2,6-dimethylpyridin-4-yl)propan-2-one
(22).
Obtained from 34 (54 mg, 0.4 mmol, 1 equiv) and 4-bromo-2,6-dimethylpyridine (186 mg, 1
mmol, 2.5 equiv) following the representative procedure and after purification by flash
chromatography (silica gel, ethyl acetate/methanol = 85:15 to 80:20): 92 mg, 96%. Yellow solid;
m.p.: 138–141 °C. 1H NMR (500 MHz, CDCl3): δ 6.74 (s, 2H), 3.44 (s, 6H), 2.41 (s, 6H), 1.88 (s,
3H); 13C{1H} NMR (125 MHz, CDCl3): δ 185.9, 157.2 (2C), 141.2, 124.2 (2C), 84.1, 43.2 (2C),
~
26.3, 24.2 (2C); IR (neat): = 3037 (w), 2977 (w), 2922 (w), 2904 (w), 1597 (m), 1567 (s), 1549

(s), 1397 (m), 1384 (m), 1356 (m), 1291 (s), 1221 (w), 1170 (s), 1063 (m), 1031 (s), 998 (m), 948
(w), 911 (w), 893 (w), 870 (w), 787 (w), 756 (w), 741 (m), 688 (m). HRMS (ESI): m/z calcd for
C12H18NO2S [M + H]+: 240.1053; found: 240.1057.
1-([1,1'-Biphenyl]-4-yl)-3-cyclohexyl-1-(dimethyl(oxo)-λ6-sulfaneylidene)propan-2-one (23).
Obtained from 1 (87 mg, 0.4 mmol, 1 equiv) and (1,1'-biphenyl)-4-yl trifluoromethanesulfonate57
(302 mg, 1.0 mmol, 2.5 equiv) following the representative procedure and after purification by
flash chromatography (silica gel, ethyl acetate/methanol = 95:5 to 92/8): 79 mg, 54%. White solid;
m.p.: 126–128 °C. 1H NMR (500 MHz, CDCl3): δ 7.62 (d, J = 7.3 Hz, 2H), 7.57 (d, J = 8.1 Hz,
2H), 7.43 (t, J = 7.7 Hz, 2H), 7.33 (t, J = 7.4 Hz, 1H), 7.29 (d, J = 8.3 Hz, 2H), 3.49 (s, 6H), 2.08
(d, J = 7.1 Hz, 2H), 1.87-1.76 (m, 1H), 1.76-1.70 (m, 5H), 1.29-1.18 (m, 2H), 1.12-1.00 (m, 1H),
0.86-0.76 (m, 2H). 13C{1H} NMR (125 MHz, CDCl3): δ 188.5, 140.4, 140.2, 135.0 (2C), 131.0,
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128.7 (2C), 127.3, 127.0 (2C), 126.9 (2C), 86.2, 45.4, 43.1 (2C), 35.2, 33.1 (2C), 26.3, 26.2 (2C).
5
6
~
IR (neat): = 3025 (w), 2918 (s), 2846 (m), 1550 (s), 1485 (m), 1446 (w), 1374 (m), 1321 (w),

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8
9
1276 (w), 1254 (w), 1228 (m), 1177 (s), 1164 (s), 1112 (m), 1076 (w), 1066 (w), 1008 (m), 1019
(m), 969 (w), 937 (w), 889 (w), 836 (w), 796 (w), 765 (m), 730 (s), 693 (s). HRMS (ESI): m/z
calcd for C23H29O2S [M + H]+: 369.1883; found: 369.1887.
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7-(1-(Dimethyl(oxo)-λ6-sulfaneylidene)-2-oxo-3,3-diphenylpropyl)-2H-chromen-2-one (24).
Obtained from 43 (115 mg, 0.4 mmol,
1
equiv) and 2-oxo-2H-chromen-7-yl
trifluoromethanesulfonate7 (294 mg, 1.0 mmol, 2.5 equiv) following the representative procedure
but using 2 mL of acetonitrile and after purification by flash chromatography (silica gel, petroleum
ether/ethyl acetate = 1:1 to ethyl acetate only) and trituration with diethyl ether: 86 mg, 50%.
Coral-colored solid; m.p.: 134–138 °C. 1H NMR (500 MHz, CDCl3): δ 7.68 (d, J = 9.5 Hz, 1H),
7.38 (d, J = 7.9 Hz, 1H), 7.29-7.23 (m, 4H), 7.23-7.17 (m, 6H), 7.14 (d, J = 0.8 Hz, 1H), 7.04 (dd,
J = 7.9, 1.5 Hz, 1H), 6.41 (d, J = 9.5 Hz, 1H), 5.07 (s, 1H), 3.53 (s, 6H). 13C{1H} NMR (125 MHz,
CDCl3): δ 186.1, 160.5, 153.6, 142.9, 140.7 (2C), 135.7, 130.6, 128.8 (4C), 128.3 (4C), 127.2,
~
126.5 (2C), 122.1, 118.0, 116.6, 85.5, 57.7, 43.1 (2C). IR (neat): = 3660 (w), 3060 (w), 3025

(w), 3008 (m), 2924 (w), 1721 (s), 1610 (m), 1540 (s), 1493 (m), 1449 (w), 1402 (m), 1360 (m),
1308 (m), 1290 (w), 1278 (w), 1247 (m), 1227 (w), 1193 (s), 1152 (m), 1134 (m), 1103 (m), 1077
(w), 1024 (s), 1013 (m), 982 (m), 941 (m), 924 (m), 909 (w), 897 (w), 878 (w), 816 (w), 784 (w),
770 (w), 750 (m), 727 (m), 719 (s), 695 (s). HRMS (ESI) m/z calcd for C26H22NaO4S [M + Na]+:
453.1131; found: 453.1136.
4-(1-(Dimethyl(oxo)-λ6-sulfaneylidene)-2-oxoethyl)benzonitrile (25). Obtained from 47 (48
mg, 0.4 mmol, 1 equiv) and 4-bromobenzonitrile (182 mg, 1 mmol, 2.5 equiv) following the
representative procedure and after purification by flash chromatography on a short pad of silica
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gel (ethyl acetate/methanol = 92:8 to 85:15; the silica was pre-treated with an ethyl
acetate/methanol/triethylamine (92:8:1) mixture, and then washed with ethyl acetate/methanol
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(92:8) before loading the crude mixture): 74 mg, 83%. Beige amorphous solid. H NMR (500
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MHz, CDCl3): δ 8.92 (s, 1H), 7.54 (d, J = 8.5 Hz, 2H), 7.35 (d, J = 8.6 Hz, 2H), 3.58 (s, 6H).
13C{1H} NMR (125 MHz, CDCl3): δ 178.0, 137.2, 132.0 (2C), 128.5 (2C), 119.1, 108.5, 87.5, 42.6
~
(2C). IR (neat): = 3661 (w), 3028 (w), 2989 (w), 2919 (w), 2903 (w), 2219 (m), 1577 (s), 1503

(m), 1415 (w), 1391 (m), 1313 (s), 1303 (s), 1275 (w), 1189 (s), 1175 (s), 1113 (w), 1076 (w),
1066 (w), 1056 (w), 1025 (s), 984 (m), 959 (m), 946 (m), 919 (w), 835 (m), 819 (m), 770 (w), 739
(m), 724 (w), 703 (m), 656 (w). HRMS (ESI): m/z calcd for C11H12NO2S [M + H]+: 222.0583;
found: 222.0585.
2-(1-(Dimethyl(oxo)-λ6-sulfaneylidene)-2-oxoethyl)benzonitrile (26). Obtained from 47 (54
mg, 0.4 mmol, 1 equiv) and 2-bromobenzonitrile (182 mg, 1 mmol, 2.5 equiv) following the
representative procedure and after purification by flash chromatography on a short pad of silica
gel (ethyl acetate/methanol = 90:10 to 84:16; the silica was pre-treated with an ethyl
acetate/methanol/triethylamine (90:10:1) mixture, and then washed with ethyl acetate/methanol
1
(90:10) before loading the crude mixture): 76 mg, 85%. Beige amorphous solid. H NMR (500
MHz, CDCl3): δ 8.75 (s, 1H), 7.63 (dd, J = 7.8, 1.1 Hz, 1H), 7.52 (td, J = 7.8, 1.5 Hz, 1H), 7.38-
7.31 (m, 2H), 3.61 (s, 6H). 13C{1H} NMR (125 MHz, CDCl3): δ 177.5, 134.9, 134.1, 132.8, 132.6,
~
127.5, 119.5, 116.1, 84.9, 42.2 (2C). IR (neat): = 3026 (w), 2995 (w, 2915 (w), 2854 (w), 2220

(m), 1154 (s), 1483 (m), 1450 (w), 1400 (m), 1358 (m), 1330 (w), 1314 (w), 1281 (w), 1261 (w),
1204 (s), 1163 (m), 1103 (w), 1004 (s), 994 (w), 949 (m), 939 (m), 877 (w), 788 (w), 763 (m), 952
(m), 742 (s), 701 (w), 686 (s). HRMS (ESI): m/z calcd for C11H12NO2S [M + H]+: 222.0583; found:
222.0583.
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(dimethylamino)ethoxy)(phenyl)methyl)phenyl)-3,3-diphenylpropan-2-one (27). Under
nitrogen, a J-Young Schlenck tube was charged with XPhos (21 mg, 0.044 mmol, 0.11 equiv),
Pd2dba3 (18 mg, 0.02 mmol, 0.05 equiv) and Cs2CO3 (143.4 mg, 0.44 mmol, 1.1 equiv).
Acetonitrile (0.4 mL) was then added and the mixture was stirred at room temperature for 10
minutes. Then, bromazine (147 mg, 0.44 mmol, 1.1 equiv) was added in solution in acetonitrile
(0.4 mL) followed by sulfoxonium ylide 43 (115 mg, 0.4 mmol, 1 equiv). The tube was then sealed,
placed in a preheated oil bath set at 80 °C and stirred for 13 hours. The crude was then filtered
over celite at room temperature using dichloromethane to transfer all the material and for rinsing.
After evaporation of all volatiles, purification by flash chromatography (silica gel, CH2Cl2/MeOH:
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95:5 to 85:15) afforded compound 27 (170 mg, 79%). Amorphous solid. H NMR (500 MHz,
CDCl3): δ 7.38-7.31 (m, 4H), 7.30-7.25 (m, 3H), 7.27-7.19 (m, 4H), 7.18-7.13 (m, 6H), 7.08 (d, J
= 8.2 Hz, 2H), 5.38 (s, 1H), 4.98 (s, 1H), 3.62 (t, J = 5.7 Hz, 2H), 3.45 (s, 6H), 2.69 (t, J = 5.8 Hz,
13
2H), 2.34 (s, 6H). C{1H} NMR (125 MHz, CDCl3): δ 186.2, 141.8, 141.6, 141.0 (2C), 134.7
(2C), 130.6, 128.8 (4C), 128.2 (2C), 127.9 (4C), 127.4, 126.9 (2C), 126.8 (2C), 126.0 (2C), 86.6,
~
83.5, 66.8, 58.5, 57.4, 45.5 (2C), 42.5 (2C). IR (neat): = 3416 (w), 3023 (w), 2971 (w), 2971

(w), 2923 (w), 2820 (w), 2771 (w), 1599 (w), 1546 (s), 1493 (m), 1451 (m), 1406 (w), 1362 (w),
1302 (w), 1266 (w), 1186 (s), 1165 (s), 1098 (m), 1073 (m), 1057 (m), 1021 (s), 971 (m), 935 (w),
853 (w), 811 (w), 784 (w), 737 (m), 697 (s). HRMS (ESI): m/z calcd for C34H38NO3S [M + H]+:
540.2567; found: 540.2570.
Tert-butyl (5-(dimethyl(oxo)-λ6-sulfaneylidene)-4-oxo-5-phenylpentyl)carbamate (29). Under
nitrogen, a J-Young Schlenck tube was charged with XPhos (189 mg, 0.396 mmol, 0.11 equiv),
Pd2dba3 (165 mg, 0.18 mmol, 0.05 equiv) and Cs2CO3 (1.29 g, 3.96 mmol, 1.1 equiv). Acetonitrile
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