Highly stereoselective and catalytic desulfitative C[sbnd]O and C[sbnd]I dienylation with sulfolenes: The importance of basic additives

Article abstract of DOI:10.1016/j.tet.2019.04.012

Conjugated dienes and polyenes are central structural motifs of natural products, and key synthetic intermediates in organic synthesis and materials science. We describe herein a palladium-catalyzed dienylation of aryl, heteroaryl, and vinyl triflates, nonaflates and iodides that were previously identified as recalcitrant substrates for the sulfolene-mediated catalytic dienylation. The method has now been successfully expanded to C[sbnd]O and C[sbnd]I dienylation, demonstrating broad scope with respect to sulfonates, iodides and sulfolenes. The reactions proceed with high regio- and stereoselectivity, and efficiency that are strongly influenced by basic additives, whose influence on the reaction performance was systematically studied.

Full text of DOI:10.1016/j.tet.2019.04.012

Tetrahedron xxx (xxxx) xxx
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Highly stereoselective and catalytic desulfitative CeO and CeI
dienylation with sulfolenes: The importance of basic additives
Hang T. Dang, Viet D. Nguyen, Hoang H. Pham, Hadi D. Arman, Oleg V. Larionov*
Department of Chemistry, The University of Texas at San Antonio, San Antonio, TX 78249, United States
a r t i c l e i n f o
a b s t r a c t
Article history:
Conjugated dienes and polyenes are central structural motifs of natural products, and key synthetic
intermediates in organic synthesis and materials science. We describe herein a palladium-catalyzed
dienylation of aryl, heteroaryl, and vinyl triflates, nonaflates and iodides that were previously identi-
fied as recalcitrant substrates for the sulfolene-mediated catalytic dienylation. The method has now been
successfully expanded to CeO and CeI dienylation, demonstrating broad scope with respect to sulfo-
nates, iodides and sulfolenes. The reactions proceed with high regio- and stereoselectivity, and efficiency
that are strongly influenced by basic additives, whose influence on the reaction performance was sys-
tematically studied.
Received 1 February 2019
Received in revised form
29 March 2019
Accepted 2 April 2019
Available online xxx
Keywords:
Cross-coupling
Desulfitation
Dienes
© 2019 Elsevier Ltd. All rights reserved.
Palladium catalysis
Polyenes
Sulfinates
Sulfolenes
1. Introduction
direct installation of a dienyl unit. However, this approach would
require development of a catalytic system that could control the
Conjugated dienes play increasingly important roles in organic
synthesis. The reactive diene moiety offers a plethora of opportu-
nities for functionalization at one, two, or all four carbon atoms in a
regio- and stereoselective manner, and significant efforts have
recently been directed towards the development of catalytic
methods of diene functionalization [1], in addition to the well-
established cycloaddition approaches [2]. Conjugated dienes are
also important precursors to functional materials and polymers [3].
More extended conjugated polyene units are common structural
motifs of natural products, some of which have been used for
treatment of infectious diseases and cancer (Fig. 1) [4]. Given the
importance of conjugated dienes and polyenes, several general
approaches were developed to access them, including olefination
reactions with ylides [5] and transition metal-catalyzed vinylation
procedures [6,7], including methods that allow for construction of
dienes and polyenes in iterative fashion [8]. While these methods
have significantly improved synthetic access to conjugated dienes
and polyenes, a dienylation approach that takes advantage of
appropriately designed four-carbon atom reagents can enable
stereoselectivity of formation of both C]C bonds in the diene unit,
and the dienylation reagents have to be readily available in a variety
of substitution patterns. Given these challenges, until recently, this
approach remained unexplored. In 2018, our group disclosed the
highly stereo- and regioselective palladium-catalyzed dienylation
of aryl, heteroaryl, and vinyl chlorides and bromides with sulfo-
lenes as four-carbon dienylation reagents (Fig. 2) [9]. The use of
sulfolenes is advantageous, because they are readily accessible by
means of scalable procedures in a variety of substitution patterns
from simple precursors, or are industrially produced bulk chem-
icals [10]. The dienylation reaction is catalyzed by palladium, and
the use of dppbz (1,2-bis(phenylphosphino)benzene) as a ligand is
required to achieve high E- and Z-stereoselectivity. The regiose-
lectivity of the dienylation is determined by the base-mediated ring
opening of sulfolenes that is structure-dependent. For example, 2-
substituted sulfolenes 1 produce 4-substituted dienesulfinates 2,
while 3-substituted sulfolenes 3 produce 2-substituted dien-
esulfinates 4. The ring-opening is also highly stereoselective: ZeC]
C bond is formed adjacent to the sulfinate group, while the distal
CeC bond has the E-configuration. The 1Z-configuration pre-
disposes the ensuing dienylation to produce 1Z-dienes that are
indeed observed for the majority of substituted sulfinates.
* Corresponding author.
E-mail address: oleg.larionov@utsa.edu (O.V. Larionov).
https://doi.org/10.1016/j.tet.2019.04.012
0040-4020/© 2019 Elsevier Ltd. All rights reserved.
Please cite this article as: H.T. Dang et al., Highly stereoselective and catalytic desulfitative CeO and CeI dienylation with sulfolenes: The
importance of basic additives, Tetrahedron, https://doi.org/10.1016/j.tet.2019.04.012

2
H.T. Dang et al. / Tetrahedron xxx (xxxx) xxx
Fig. 1. Conjugated dienes and polyenes.
However, highly stereoselective formation of 1E-dienes was
observed for some sulfolenes. These results point to the isomeri-
zation of the dienesulfinate moiety either at the stage of dien-
esulfinate salts 5, or at the stage of arylpalladium(II) sulfinate
intermediate 6. Both isomerization processes can be catalyzed by
basic reagents that are present in the reaction mixture, for example,
potassium carbonate, as was previously shown for salts of type 5.
Indeed, presence of potassium carbonate as a basic additive was
crucial for achieving high stereoselectivity and high yields. Car-
bonates are known to rapidly react with sulfur dioxide [11] that is
produced in the desulfitation of arylpalladium sulfinate 6 en route
to aryldienylpalladium 7. The role of potassium carbonate can
therefore be twofold: it can catalyze the isomerization of sulfinates
5 and 6, and remove the sulfur dioxide from the reaction mixture,
thus facilitating the potentially reversible desulfitation step [12].
2. Results and discussion
Fig. 2. Palladium-catalyzed dienylation.
Although the dienylation reaction exhibited a broad substrate
scope with respect to aryl, heteroaryl and vinyl halides, as well as
various substituted sulfolenes, the reaction was incompatible with
aryl triflates. For example, an attempted dienylation of triflate 8
with sulfolene 9 produced diene 10 in only 9% yield and with 1; 1 E/
Z ratio (Scheme 1). In addition, phenol 11 was formed in 49% yield,
indicating that a base-mediated cleavage of the base-labile triflate
group can be responsible for the incompatibility of aryl triflates.
Aryl sulfonates, particularly triflates, are key synthetic in-
termediates that are used to convert C(sp2)ÀO bonds to CeC bonds
by a variety of catalytic transformations. The synthetic importance
of the C(sp2)ÀO bond stems from the abundance of phenols among
synthetic precursors of industrial and biological origin, and the
ready availability of vinyl triflates from carbonyl compounds. The
incompatibility of the dienylation reaction with sulfonates is,
therefore, a serious impediment for its synthetic application in the
areas that capitalize on the availability of efficient and stereo-
selective C(sp2)ÀO functionalization reactions, e.g., natural product
synthesis and medicinal chemistry. In addition, by extending the
scope of the dienylation reaction to these substrates, we hoped to
gain better understanding of the roles of the reagents that are used
in the reaction. Given that both potassium methoxide and potas-
sium carbonate can have deleterious effects on the stability of tri-
flate substrates, we first embarked on the study of the influence of
basic additives on the stereoselectivity and efficiency of the dien-
ylation reaction with dienesulfinate salt 12, thus excluding potas-
sium methoxide from the reaction mixture (Table 1). Interestingly,
the reaction with potassium carbonate resulted in 84% yield of
diene 10 with a 1.5 : 1 E/Z ratio (entry 1), confirming that the basic
additive is responsible for the low stereoselectivity in THF.
This result highlights the important role that the basic additive
plays in determining the stereoselectivity of the dienylation reac-
tion. Replacement of THF with dioxane as a solvent had a detri-
mental effect (entry 2), favoring triflate cleavage. The reaction
proceeded substantially better in toluene (entry 3), although the
Please cite this article as: H.T. Dang et al., Highly stereoselective and catalytic desulfitative CeO and CeI dienylation with sulfolenes: The
importance of basic additives, Tetrahedron, https://doi.org/10.1016/j.tet.2019.04.012

H.T. Dang et al. / Tetrahedron xxx (xxxx) xxx
3
(phenol 11 and 4-methoxybenzonitrile). This result indicated that
in addition to the carbonate-induced cleavage of the triflate group,
the reaction also suffered from the deleterious effects of the
nucleophilicity of potassium methoxide.
Our prior experiments showed that although the methoxide-
induced ring opening of sulfolene 9 is completed within 10 min at
110 ꢀC it is very slow at room temperature, thus leaving ample time
for the unproductive triflate cleavage by the methoxide. On the
other hand, potassium tert-butoxide effects a fast sulfolene ring
opening even at room temperature. We therefore tested the two-
flask procedure, wherein sulfolene 9 and potassium tert-butoxide
were allowed to react separately at room temperature for 1 h,
before being added to the reaction vessel with the catalyst. This
procedure afforded diene 10 with the same high E-stereoselectivity
and 81% yield. With this simple procedure in hand we proceeded to
test the scope of the triflate dienylation with sulfolene 9 (Fig. 3). A
variety of products (13e32) bearing cyano (10, 13), halogen
(14e16), alkyl (17), alkylthio (18), methoxy (19), and fluorinated
groups (20, 21) were tolerated. Keto and ester groups (23 and 24)
were suitable, as well bicyclic aromatic substrates (25e27). All
substitution patterns (ortho, meta and para) were well-tolerated.
Heteroaryl triflates of the pyridine and quinoline series and the
estrone-derived triflate also afforded the corresponding dienes
28e33 in synthetically useful yields.
Scheme 1. Attempted dienylation of triflate 8.
Table 1
Optimization of CeO dienylationa.
Entry
Basic additive
Solvent
Yield, %b
E/Z ratio
We also tested the triflate dienylation protocol with various
natural product-derived vinyl triflates. Despite the pronounced
propensity for polymerization, polyenes 34e37 derived from
cholesterol, stigmasterol, diosgenin, and ergosterol were readily
obtained from the corresponding triflates. The newly-established
synthetic access to the highly air-sensitive ergosterol-derived
pentaene 37 highlights the potential of the triflate dienylation
procedure for preparation of polyenes. Conversion of unsaturated
ketones to conjugated polyenyl triflates typically proceeds under
milder conditions than conversion to the corresponding bromides.
Hence, the new triflate dienylation procedure can be particularly
useful for the synthesis of polyenes with labile vinyl bromide
precursors.
1
2
3
4
5
6
7
8
K
K
K
CO
CO
CO
THF
84
0c
1.5:1
e
2
2
2
3
3
3
Dioxane
Toluene
THF
THF
THF
THF
THF
THF
THF
68
13d
47
92
55
40
49
35
71
81e
21:1
Cs2CO3
Li2CO3
Na2CO3
K3PO4
K2HPO4
KH2PO4
Na2HPO4
Li3PO4
>30:1
>30:1
5.7:1
22:1
>30:1
>30:1
>30:1
>30:1
>30:1
9
10
11
12
THF
THF
KHCO3
a
Reaction conditions: triflate 8 (1 mmol), sulfinate 12 (2 mmol), Pd(OAc)2 (5 mol
%), dppbz (8 mol %), basic additive (2 mmol), solvent (9 mL), 100 ꢀC, 18 h.
b
Determined by 1H NMR spectroscopy with 1,4-dimethoxybenzene as an inter-
Nonaflates (nonafluorobutanesulfonates, RONf) are cost-
effective and reactive electrophiles that have found use in CeC
bond-forming cross-coupling reactions and other synthetic appli-
cations [13]. Nonaflates can be readily accessed from the inexpen-
sive and bench-stable nonaflyl fluoride (NfF), and their use can be
particularly advantageous in large-scale CeO functionalization
applications. We, therefore, tested the performance of a series of
aryl nonaflates in the newly-developed dienylation protocol. In all
of the cases, dienes 10, 19, 24 and 31 were produced in good yields,
indicating that nonaflates are also suitable substrates for the
dienylation protocol.
nal standard.
c
Phenol 11 was produced in 67% yield.
Phenol 11 was produced in 85% yield.
Isolated yield.
d
e
stereoselectivity was not as high as for the dienylation of aryl ha-
lides. Carbonates of other alkali metals showed disparate but
overall unsatisfactory performance. While low yields and high
stereoselectivity were observed for cesium and lithium carbonates
(entries 4 and 5), high yield and low stereoselectivity was observed
for sodium carbonate (entry 6).
We further proceeded to test the triflate dienylation procedure
with substituted sulfolenes (Fig. 4). 2,4-Substituted sulfolene 38
reacted smoothly with aryl and heteroaryl triflates, producing di-
enes 39 and 40 with >30 : 1 stereoselectivity and in excellent
yields. The dienes share the 1Z,2E configuration in line with the
reactivity observed for aryl halides and as predicted by the stereo-
and regiochemical model of the sulfolene ring-opening process.
The desulfitative coupling with sulfolene 38 was 1Z-selective.
Substituted polyenes 41e42 were also prepared from stigmasterol
and cholesterol-derived vinyl triflates, confirming applicability of
the dienylation procedure for polyene synthesis. Estrone-derived
diene 43 was also prepared in a good yield. The structure of het-
erocyclic diene 40 was confirmed by single crystal X-ray crystal-
lographic analysis (Fig. 5a). Trisubstituted sulfolene 44 also reacted
with high stereoselectivity, affording diversely substituted 1Z-di-
enes 45e48 in good yields. Similarly, 3-substituted myrcene-
derived sulfolene 49 produced 1Z-dienes 50e52 with >30 : 1 Z-
We then proceeded to investigate the influence of other basic
salts on the reaction performance. Although the reaction with po-
tassium phosphate afforded diene 10 in a fairly good yield, the E-
stereoselectivity was below 30 : 1 (entry 7). On the other hand, both
potassium hydrogen phosphate and dihydrogen phosphate gave
rise to diene 10 with very high E/Z ratio, albeit at the expense of the
yield (entries 8, 9). Various sodium and lithium phosphate salts
were also investigated (e.g., entries 10 and 11). In both cases high
stereoselectivity was observed, but the yield remained unsatisfac-
tory. Gratifyingly, when potassium hydrogen carbonated was used,
diene 10 was produced essentially as a single E-isomer, and in 81%
yield. With this result in hand, we proceeded to test the dienylation
reaction with potassium hydrogen carbonate as a basic additive and
potassium methoxide as a base. Surprisingly, the reaction did not
produce any dienylation product, instead affording a mixture of
products of triflate cleavage and substitution with methoxide
Please cite this article as: H.T. Dang et al., Highly stereoselective and catalytic desulfitative CeO and CeI dienylation with sulfolenes: The
importance of basic additives, Tetrahedron, https://doi.org/10.1016/j.tet.2019.04.012

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H.T. Dang et al. / Tetrahedron xxx (xxxx) xxx
Fig. 3. Conjugated dienes and polyenes obtained with sulfolene 9. Aryl and vinyl triflates were used, and E/Z ratio >30:1 unless otherwise specified.
selectivity and in good yields. The results with substituted sulfo-
lenes 9, 38, 44 and 49 confirm broad scope of the triflate dien-
ylation procedure with a variety of sulfolenes and triflates. In all of
the cases, only the dienylation products were formed, and dien-
esulfones that may be produced by a reaction of halo(hetero)arenes
with dienesulfinate salts 5 were not observed [14]. The success of
the present study hinged on identification of potassium hydrogen
carbonate as a basic additive that can efficiently sequester sulfur
dioxide and catalyze the Z/E-isomerization of the dienesulfinate
unit (in the case of sulfolene 9), but that is not basic enough to
cleave labile aryl sulfonates. Use of strongly basic potassium tert-
butoxide to accelerate the ring-opening of sulfolenes allowed for
by-passing potassium methoxide that was also responsible for the
unproductive cleavage of triflate esters.
developed for bromide and chloride substrates. The behavior of the
catalytic dienylation system stands in stark contrast to the majority
of other palladium-catalyzed cross-coupling reactions, for which
aryl iodides are typically the most reactive electrophiles [15]. Aryl
iodides are less cost-effective and less readily available than aryl
bromides, chlorides and sulfonates, and they are typically only used
when the more readily obtainable electrophiles do not show
satisfactory performance. We were, however, intrigued by the
challenge of circumventing the lack of reactivity of iodides in the
catalytic dienylation and endeavored to extend the scope of the
dienylation reaction to C(sp2)ÀI bonds. Our initial attempts to effect
conversion of iodide 53 to diene 10 confirmed that alkali carbonate
and phosphate salts were not suitable as basic additives for CeI
dienylation (Table 2, entries 1e3). Prompted by our earlier research
on Pd-catalyzed functionalization of heterocyclic N- oxides [16]
that showed the superior performance of basic silver salts, espe-
cially with aryl iodides as electrophiles, we employed silver oxide
With the catalytic dienylation of triflates and nonaflates
secured, we proceeded with the study of the dienylation of iodides
that were also found to be resistant to the reaction conditions
Please cite this article as: H.T. Dang et al., Highly stereoselective and catalytic desulfitative CeO and CeI dienylation with sulfolenes: The
importance of basic additives, Tetrahedron, https://doi.org/10.1016/j.tet.2019.04.012

H.T. Dang et al. / Tetrahedron xxx (xxxx) xxx
5
Fig. 4. Dienylation products obtained with substituted sulfolenes 38, 44 and 49. Aryl and vinyl triflates were used, and E/Z ratio >30:1 unless otherwise specified.
as a basic additive and observed a much improved catalytic per-
formance and stereoselectivity (entry 4). Interestingly, the rate-
enhancing effect was limited to silver oxide, while reactions with
copper(I) oxide, as well as other basic silver salts (e.g., carbonate
and phosphate) did not produce diene 10 (entries 5e7). Replacing
potassium methoxide with potassium tert-butoxide resulted in
higher stereoselectivity, albeit at the expense of lower yield.
Further improvement in yield was achieved by reducing concen-
tration of the reactants, likely due to improved mixing (entry 9).
Increased loading of potassium tert-butoxide and sulfolene 9
further improved the yield and stereoselectivity, although, even
after further optimization, the performance of the CeI dienylation
could not achieve the levels of CeBr and CeO dienylation. Several
aryl iodides were evaluated in the dienylation reaction with sul-
folenes 9 and 38 (Figs. 3 and 4). Dienes 10, 13, 18, 21 (Fig. 3) and 54,
55 (Fig. 4) were obtained with high stereoselectivities, confirming
that CeI dienylation can be used to directly access conjugated di-
enes from aryl iodides. The structure of diene 55 was confirmed by
single crystal X-ray crystallographic analysis (Fig. 5b).
The beneficial role of silver oxide may be explained by facilita-
tion of the anion metathesis en route to arylpalladium sulfinate
intermediate 6 (Fig. 2) that may be sluggish in the case of the
iodide.
3. Conclusion
In summary, we developed
a simple procedure for the
palladium-catalyzed, highly stereoselective dienylation of triflates,
nonaflates and iodides that are not compatible with the dienylation
method developed for chlorides and bromides. The new protocol
allows for efficient and highly stereoselective conversion of triflates
and nonaflates to substituted dienes and polyenes. The develop-
ment of this protocol was enabled by a study of the influence of
basic additives on the stereoselectivity and efficiency of dien-
ylation. Potassium hydrogen carbonate was found to be the basic
additive of choice for sulfonates, while silver oxide was the optimal
Please cite this article as: H.T. Dang et al., Highly stereoselective and catalytic desulfitative CeO and CeI dienylation with sulfolenes: The
importance of basic additives, Tetrahedron, https://doi.org/10.1016/j.tet.2019.04.012

6
H.T. Dang et al. / Tetrahedron xxx (xxxx) xxx
(CHE-1455061 and CHE-1625963), NIGMS (SC3GM105579), Max
and Minnie Tomerlin Voelcker Fund, and the Brown Foundation is
gratefully acknowledged.
Appendix A. Supplementary data
Supplementary data to this article can be found online at
https://doi.org/10.1016/j.tet.2019.04.012.
References
[1] (a) G.L.J. Bar, G.C. Lloyd-Jones, K.I. Booker-Milburn, J. Am. Chem. Soc. 127
(2005) 7308;
(b) H. Du, B. Zhao, Y. Shi, J. Am. Chem. Soc. 129 (2007) 762;
(c) L. Liao, R. Jana, K.B. Urkalan, M.S. Sigman, J. Am. Chem. Soc. 133 (2011)
5784;
ꢀ
(d) M.A. Bohn, A. Schmidt, G. Hilt, M. Dindaroglu, H.-G. Schmalz, Angew.
Chem. Int. Ed. 50 (2011) 9689;
(e) J.C. Leung, L.M. Geary, T.-Y. Chen, J.R. Zbieg, M.J. Krische, J. Am. Chem. Soc.
134 (2012) 15700;
(f) E. McNeill, T. Ritter, Acc. Chem. Res. 48 (2015) 2330;
(g) Y.N. Timsina, R.K. Sharma, T.V. RajanBabu, Chem. Sci. 6 (2015) 3994;
(h) X.-H. Yang, V.M. Dong, J. Am. Chem. Soc. 139 (2017) 1774;
(i) S.R. Sardini, M.K. Brown, J. Am. Chem. Soc. 139 (2017) 9823;
(j) A. Tortajada, R. Ninokata, R. Martin, J. Am. Chem. Soc. 140 (2018) 2050;
(k) X. Wu, L.Z. Gong, Synthesis 51 (2019) 122.
Fig. 5. X-Ray crystallographic structure of dienes 40 (a) and 55 (b) with ellipsoids
shown at the 65% probability level.
[2] (a) E.J. Corey, Angew. Chem. Int. Ed. 41 (2002) 1650;
(b) F. Fringuelli, A. Taticchi, The Diels-Alder Reaction: Selected Practical
Methods, John Wiley & Sons, Ltd, Chichester, 2002;
(c) Y. Yamamoto, H. Yamamoto, Eur. J. Org. Chem. 9 (2006) 2031.
[3] (a) M.D. Beery, M.K. Rath, V.V. Sheares, Macromolecules 34 (2001) 2469;
(b) L. Li, S. Li, D. Cui, Macromolecules 49 (2016) 1242.
Table 2
Optimization of CeI dienylationa.
[4] (a) S. Hanessian, Natural Products in Medicinal Chemistry, Wiley-VCH,
Weinheim, 2014;
(b) S.D. Rychnovsky, Chem. Rev. 95 (1995) 2021;
(c) C. Thirsk, A. Whiting, J. Chem. Soc., Perkin Trans. 1 (8) (2002) 999;
(d) H. Inano, K. Suzuki, H. Ishii-Ohba, H. Yamanouchi, M. Takahashi,
K. Wakabayashi, Carcinogenesis 14 (1993) 2157;
(e) I.H. Paik, S.J. Xie, T.A. Shapiro, T. Labonte, A.A.N. Sarjeant, A.C. Baege,
G.H. Posner, J. Med. Chem. 49 (2006) 2731.
[5] (a) G. Mehta, H.S. Prakash Rao (Eds.), John Wiley & Sons, Ltd, Chichester, 1997;
(b) M. De Paolis, I. Chataigner, J. Maddaluno, Top. Curr. Chem. 327 (2012) 87.
[6] (a) A.L. Hansen, J.P. Ebran, M. Ahlquist, P.O. Norrby, T. Skrydstrup, Angew.
Chem. Int. Ed. 45 (2006) 3349;
Entry
Basic additive
Base
Yield, %b
E/Z ratio
1
2
3
4
5
6
7
8
K2CO3
K3PO4
Cs2CO3
Ag2O
KOMe
KOMe
KOMe
KOMe
KOMe
KOMe
KOMe
KOtBu
KOtBu
KOtBu
9%
1:1
12%
15%
59%
e
1:1.7
1.5:1
15:1
e
(b) E.-I. Negishi, Z. Huang, G. Wang, S. Mohan, C. Wang, H. Hattori, Acc. Chem.
Res. 41 (2008) 1474;
(c) C. Zheng, D. Wang, S.S. Stahl, J. Am. Chem. Soc. 134 (2012) 16496.
[7] (a) S.L. Buchwald, R.B. Nielsen, J. Am. Chem. Soc. 111 (1989) 2870;
(b) J. Ryan, G.C. Micalizio, J. Am. Chem. Soc. 128 (2006) 2764;
(c) I.T. Crouch, T. Dreier, D.E. Frantz, Angew. Chem. Int. Ed. 50 (2011) 6128;
(d) X.-H. Hu, J. Zhang, X.-F. Yang, Y.H. Xu, T.-P. Loh, J. Am. Chem. Soc. 137
(2015) 3169;
Cu2O
Ag2CO3
Ag3PO4
Ag2O
Ag2O
Ag2O
e
e
e
e
45%
55%
60%
>30:1
27:1
>30:1
9c
10c,d
(e) A.M. Olivares, D.J. Weix, J. Am. Chem. Soc. 140 (2018) 2446;
(f) M. Liu, P. Yang, M.K. Karunananda, Y. Wang, P. Liu, K.M. Engle, J. Am. Chem.
Soc. 140 (2018) 5805.
a
Reaction conditions: iodide 53 (1 mmol), sulfolene 9 (2 mmol), Pd(OAc)2 (5 mol
%), ligand (8 mol%), base (1.6 mmol), basic additive (2 mmol), THF (10 mL), 16 h.
[8] (a) S.J. Lee, K.C. Gray, J.S. Paek, M.D. Burke, J. Am. Chem. Soc. 130 (2008) 466;
(b) S.J. Lee, T.M. Anderson, M.D. Burke, Angew. Chem. Int. Ed. 49 (2010) 8860;
(c) E.M. Woerly, J. Roy, M.D. Burke, Nat. Chem. 6 (2014) 484;
(d) J. Li, A.S. Grillo, M.D. Burke, Acc. Chem. Res. 48 (2015) 2297.
[9] (a) V.T. Nguyen, H.T. Dang, H.H. Pham, V.D. Nguyen, C. Flores-Hansen,
H.D. Arman, O.V. Larionov, J. Am. Chem. Soc. 140 (2018) 8434;
b
Determined by 1H NMR spectroscopy with 1,4-dimethoxy-benzene as an in-
ternal standard.
c
15 mL of THF was used.
2 equiv. of KOtBu and 2.2 equiv. of sulfolene 9 were used.
d
(b) For
a Pd-catalyzed dienylation with cyclobutene, see: N.J. McAlpine,
L. Wang, B. Carrow J. Am. Chem. Soc. 140 (2018) 13634.
[10] (a) L. Martial, L. Bischoff, Synlett 26 (2015) 1225;
(b) H.T. Dang, V.T. Nguyen, V.D. Nguyen, H.D. Arman, O.V. Larionov, Org.
Biomol. Chem. 16 (2018) 3605.
reagent for iodides. The scope of the reaction was found to
encompass a variety of functional groups. Aryl, heteroaryl and vinyl
triflates were readily converted to conjugated dienes and polyenes
in good to excellent yields and with high regio- and stereo-
selectivity. In addition, several substituted sulfolenes were suc-
cessfully used as dienylation reagents, indicating that the reaction
can be used to prepare substituted dienes, in particular, the more
synthetically challenging Z-dienes with a variety of substitution
patterns.
[11] (a) T.C. Keener, W.T. Davis, JAPCA 34 (1984) 651;
(b) S. Kimura, J.M. Smith, AIChE J. 33 (1987) 1522;
€
(c) E. Lippert, K. Mocek, E. Erdos, Collect. Czechoslov. Chem. Commun. 59
(1994) 2357.
[12] (a) G. Pelzer, J. Herwig, W. Keim, R. Goddard, Russ. Chem. Bull. 47 (1998) 904;
(b) S.R. Dubbaka, P. Vogel, Angew. Chem. Int. Ed. 44 (2005) 7674;
(c) S.G. Modha, V.P. Mehta, E.V. Van der Eycken, Chem. Soc. Rev. 42 (2013)
5042;
ꢁ
(d) K. Yuan, J.-F. Soule, H. Doucet, ACS Catal. 5 (2015) 978;
(e) D.H. Ortgies, A. Hassanpour, F. Chen, S. Woo, P. Forgione, Eur. J. Org. Chem.
3 (2016) 408.
[13] (a) J. Hoegermeier, H.U. Reissig, Adv. Synth. Catal. 351 (2009) 2747;
(b) H. Vorbrggen, Synthesis 8 (2008) 1165;
Acknowledgments
(c) R. Zimmer, M. Webel, H.-U. Reissig, J. Prakt. Chem. 340 (1998) 274.
[14] V.D. Nguyen, V.T. Nguyen, G.C. Haug, H.T. Dang, H.D. Arman, W.C. Ermler,
Financial support by the Welch Foundation (AX-1788), the NSF
Please cite this article as: H.T. Dang et al., Highly stereoselective and catalytic desulfitative CeO and CeI dienylation with sulfolenes: The
importance of basic additives, Tetrahedron, https://doi.org/10.1016/j.tet.2019.04.012

H.T. Dang et al. / Tetrahedron xxx (xxxx) xxx
H.D. Arman, O.V. Larionov, ACS Catal. 5 (2015) 167;
7
O.V. Larionov, ACS Catal. (9) (2019) 4015e4024.
[15] A. de Meijere (Ed.), Handbook of Organopalladium Chemistry for Organic
Synthesis by E.-i. Negishi, John Wiley & Sons, Inc., Hoboken, 2002.
[16] (a) D.E. Stephens, J. Lakey-Beitia, A.C. Atesin, T.A. Ates¸ in, G. Chavez,
(b) D.E. Stephens, J. Lakey-Beitia, G. Chavez, C. Ilie, H.D. Arman, O.V. Larionov,
Chem. Commun. 51 (2015) 9507;
(c) D.E. Stephens, O.V. Larionov, Tetrahedron 71 (2015) 8683.
Please cite this article as: H.T. Dang et al., Highly stereoselective and catalytic desulfitative CeO and CeI dienylation with sulfolenes: The
importance of basic additives, Tetrahedron, https://doi.org/10.1016/j.tet.2019.04.012