P-Anisaldehyde-Photosensitized Sulfonylcyanation of Chiral Cyclobutenes: Enantioselective Access to Cyclic and Acyclic Systems Bearing All-Carbon Quaternary Stereocenters

Article abstract of DOI:10.1021/acs.orglett.9b04345

The photosensitized p-Anisaldehyde-mediated addition of sulfonylcyanides onto the I -system of cyclobutenes is shown to afford highly functionalized cyclobutanes in high yields and diastereocontrol. The homochiral cyclobutene precursors are accessible on multigram scale in two steps through an asymmetric [2 + 2] cycloaddition/vinyl thioether reduction sequence. The enantiopure cyclobutylnitriles can be elaborated further through SmI₂-mediated ring opening or converted into new enantiopure cyclobutenes through base-mediated sulfone elimination.

Full text of DOI:10.1021/acs.orglett.9b04345

Letter
Cite This: Org. Lett. XXXX, XXX, XXX−XXX
pubs.acs.org/OrgLett
p‑Anisaldehyde-Photosensitized Sulfonylcyanation of Chiral
Cyclobutenes: Enantioselective Access to Cyclic and Acyclic Systems
Bearing All-Carbon Quaternary Stereocenters
Vincent Pirenne,† Iman Traboulsi,
,§
†,§
Lisa Rouvier
ic Robert,† and Yannick Landais*
́
e, Jonathan Lusseau, Step
́
hane Massip,‡
†
†
̀
Dario M. Bassani,† Fred
er
,†
́
†
‡
CNRS, Bordeaux INP, ISM, UMR 5255, University of Bordeaux, F-33400 Talence, France
European Institute of Chemistry and Biology (IECB), University of Bordeaux, 2 Rue Robert Escarpit, 33600 Pessac, France
S Supporting Information
*
ABSTRACT: The photosensitized p-anisaldehyde-mediated addition of sulfo-
nylcyanides onto the π-system of cyclobutenes is shown to afford highly
functionalized cyclobutanes in high yields and diastereocontrol. The homochiral
cyclobutene precursors are accessible on multigram scale in two steps through an
asymmetric [2 + 2] cycloaddition/vinyl thioether reduction sequence. The
enantiopure cyclobutylnitriles can be elaborated further through SmI -mediated
2
ring opening or converted into new enantiopure cyclobutenes through base-mediated sulfone elimination.
4
hiral cyclopropanes and cyclobutanes constitute key
and cyclobutenes. Cyclopropenes thus show a high reactivity
4a−d
C
fragments in a number of natural products and bioactive
toward addition of organometallic species
the extension of the strategy to cyclobutenes proved more
difficult as illustrated by recent studies. A similar trend is
observed in free-radical additions, where the reactivity of
cyclobutenes was shown to be on the same order as that of
cyclohexene and lower than that of cyclopropenes. Radical
additions to cyclopropenes and cyclobutenes are thus rare.
Xanthate transfer addition reactions on these highly strained
rings have, however, been described concomitantly by Zard,
and co-workers, but the scope is narrow and yields and
diastereoselectivities moderate (Scheme 1a).
In the course of our studies on free-radical functionalization of
olefins, we have developed a three-component carbocyanation
of cyclopropenes which led to the formation of the
corresponding cyclopropanes in satisfying yields and moderate
but, as expected,
1
substrates relevant to pharmaceutical use. Among the small
rings, cyclopropanes hold a special place and have therefore
monopolized the attention of organic chemists due to their
inherent ring strain, useful in ring expansion and ring-opening
5
6
2
reactions. In contrast, cyclobutanes have attracted much less
6
,7
8
interest, although their incorporation in bioactive targets is
becoming more popular in the context of drug design (e.g.,
7b
1
mirogabalin, Scheme 1). Cyclopropanes and cyclobutanes can
6
Saici
̌
c,
́
3
be constructed in many ways, including through addition onto
their unsaturated analogues and highly strained cyclopropenes
Scheme 1. Free-Radical Functionalization of Chiral
Cyclobutenes
9
diastereoselectivities. Our efforts to extend the strategy to the
cyclobutene series proved nevertheless unsuccessful, illustrating
the relatively poor reactivity of the π-system in cyclobutenes.
The restricted access to chiral enantiopure cyclobutenes and the
limited number of studies on additions onto cyclobutenes thus
prompted us to develop a straightforward access to this class of
olefins and to revisit their reactivity toward free-radical species.
We report here on the development of a multigram scale
enantioselective synthesis of cyclobutenes I and on the
photocatalyzed addition of an electrophilic sulfonyl radical and
a cyanide group across the π-system of I (Scheme 1b), which
affords access to highly functionalized cyclobutanes II in a
completely regio- and diastereoselective manner. The subse-
quent functionalization of II is also documented and includes
regioselective free-radical cyclobutane ring opening, providing
Received: December 3, 2019
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.orglett.9b04345
Org. Lett. XXXX, XXX, XXX−XXX

Organic Letters
Letter
enantioenriched cyanosulfones III bearing an all-carbon
quaternary stereocenter or new cyclobutenes, efficient Michael
acceptors ultimately leading to tetra-substituted cyclobutanes
IV, which are useful intermediates in stereoselective elaboration
of more complex structural motifs.
The removal of the SMe substituent was carried out using a
combination of Lindlar’s catalyst and a sacrificial alkene,
14
allowing full conversion of 3a into 4a without over-reduction of
the latter (Table S1). Noteworthy, careful measurement of the
enantiomeric excess of 3a and 4a indicates that the sequence
occurs without erosion of the enantioselectivity during the
thioether reduction step. This method was then extended to the
preparation of a series of cyclobutenes 4b−h, showing the
compatibility of the reduction with the presence of silyl ethers
and chlorides. This two-step strategy thus constitutes a reliable
method for the enantioselective synthesis of cyclobutenes 4 and
is amenable to large-scale synthesis, as illustrated with the
preparation of cyclobutenes 4a, 4d, and 4e.
10
Efficient routes to enantiopure cyclobutenes are relatively
rare as compared to the easy synthesis of parent cyclo-
1
1
propenes. A recent example of cyclopropene ring expansion
12
into cyclobutenes related to I was reported by Marek et al., but
there is no general method for the enantioselective synthesis of
13
cyclobutenes such as I (Scheme 1). We thus developed a rapid
access to I, based on the asymmetric [2 + 2] cycloaddition
reaction between α,β-unsaturated N-acyloxazolidinones 1 and
alkynyl sulfides 2a−h catalyzed by a cheap chiral titanium
As mentioned above, cyclobutenes exhibit a limited reactivity
toward radical species, despite their reported reaction with alkyl
10
reagent, devised earlier by Narasaka and co-workers, which
provided the corresponding cyclobutenyl sulfides 3a−h in good
yields and high enantioselectivities (Scheme 2 and Supporting
Information (SI)).
6
,7b
xanthates and our own experience with addition of BrCCl or
3
bromomalonate (see SI). Cyclobutene 4a was thus submitted to
the photocatalyzed radical addition of EtSO CN, considering
2
the high electrophilicity of sulfonyl radicals and their known
efficient additions onto olefins, including cyclic ones.
1
5
Scheme 2. Preparation of Cyclobutenes 4a−h
Application of our recently described eosin-mediated olefin
16
sulfonylcyanation (Eosin-Y, K HPO , DMF, green LEDs)
2
4
effectively furnished the addition product 5a as the major all-
trans-isomer (dr >19:1:1) (Table 1, entry 1), whose structure
was unambiguously assigned through X-ray diffraction studies
(
XRDS). This shows that the sulfonyl radical approaches anti
relative to the oxazolidinone moiety, with the cyanide group
being then delivered anti relative to the bulky sulfonyl fragment.
Although the stereoselectivity was high, yields were not
satisfactory, particularly when scaling up was envisioned. For
instance, 47% yield of 5a was obtained when the reaction was
performed on a 24 mmol scale. An alternative way to generate
the electrophilic sulfonyl radical was thus looked for. Recent
17
studies by Melchiorre et al. showed that photocatalysts having
18
−1
high triplet energy levels (around 70 kcal·mol ), such as p-
anisaldehyde and benzophenone (BP), are able to sensitize alkyl
halides and could be engaged in atom transfer radical additions
(
ATRA). It was anticipated that such catalysts might be able to
activate sulfonyl cyanides in a similar way.
Using UV-A irradiation (325−400 nm) and MeSO CN, p-
2
anisaldehyde or BP (Table 1, entries 3 and 5) effectively
Table 1. Photosensitized Sulfonylcyanation of Cyclobutene 4a
a
b
c
entry
PC
RSO CN
product
hυ (nm)
solvent
yield (%)
2
1
2
3
4
5
6
7
8
9
Eosin-Y
Eosin-Y
p-anisaldehyde
Et
Me
Me
Me
5a
5b
5b
5b
5b
5c
5c
5b
5b
513
513
DMF
DMF
47−70
48
80
41
75
50
7
d,e
d,e
325−400
325−400
325−400
325−400
325−400
254
CD CN
3
CD CN
3
BP
Me
CD CN
3
p-anisaldehyde
p-Tol
p-Tol
Me
CD CN
3
CD CN
3
p-anisaldehyde
CD CN
3
Me
254
CD CN
3
a
b
RSO CN (2 equiv); photocatalysts (PC), Eosin-Y (2 mol %), p-anisaldehyde (20 mol %); BP, benzophenone (20 mol %). Green LED (513
2
c
d
e
nm); UV-A (325−400 nm). NMR yield. Complex mixture. Reaction performed in a quartz vessel.
B
DOI: 10.1021/acs.orglett.9b04345
Org. Lett. XXXX, XXX, XXX−XXX

Organic Letters
Letter
mediated the addition process, leading to 5b in good yields, thus
illustrating the first example of a triplet photosensitized olefin
sulfonylcyanation. Reaction under UV-A in the absence of p-
anisaldehyde also provided 5b, albeit in much lower yield as a
result of direct absorption by substrate 4a at 325−400 nm (SI
and Table 1, entry 4). The critical role of p-anisaldehyde in this
process is highlighted when using oct-1-ene, which does not
absorb light in the 325−400 nm region. Sulfonylcyanation of
oct-1-ene thus led to the desired product, with >95% conversion
yields and more straightforward purifications on a larger scale
(Scheme 3). Better yields were also observed using less hindered
Scheme 3. Eosin-Y or p-Anisaldehyde-Mediated
Sulfonylcyanation of Cyclobutenes 4a−h
(
97% isolated yield after 24 h), in the presence of p-anisaldehyde
and only 25% in its absence after 20 h irradiation (see SI). A
similar trend was observed with p-TolSO CN, with 5c being
2
formed in only 7% in the absence of p-anisaldehyde (Table 1,
entries 6 and 7). The reaction was also performed at 254 nm,
leading to complete consumption of 4a and the formation of a
complex mixture in which 5b was absent, in contrast with
1
9
literature reports (Table 1, entries 8 and 9). Finally, several
control experiments were performed (SI). For instance, in the
absence of light, no trace of cyanosulfone 5b was observed.
When the sulfonylcyanation of 4a was carried out using
MeSO CN and p-anisaldehyde (20 mol %), but in the presence
2
of a triplet quencher such as 2,5-dimethylhexa-2,4-diene (20 mol
%
), 5b could not be detected after 20 h of irradiation (SI). A
similar result was observed in the presence of pyridazine, which
possesses a triplet-state energy lower than that of p-
anisaldehyde.
The results above are consistent with a mechanism involving
energy transfer from the excited triplet state of the sensitizer to
the sulfonylcyanide. Alternative mechanisms involving photo-
induced electron transfer from triplet p-anisaldehyde or BP to
the sulfonylcyanide are calculated to be thermodynamically less
2
0
favorable (see SI). The efficiency of the photosensitizer can be
assessed by comparing the photochemical quantum efficiency
for the formation of 5b in the absence and presence of the
sensitizer. The quantum yield for the formation of 5b from 4a, in
the absence of photosensitization, was determined to be 0.09
MeSO CN. The diastereoselectivity of the sulfonylcyanation
2
reaction was in all cases high (dr >19:1:1) in favor of the all-
trans-product. The stereochemistry of 5b and 5d−q was
assigned based on the configuration of 5a and 5c, obtained
through XRDS (vide supra). The yield decreased significantly
for hindered cyclobutenes (e.g., 5m,n bearing a bulky TBDMS
substituent). The process is compatible with chains bearing a
chlorine atom (5i,j) and with silyl ethers (5d−g). The reaction is
not restricted to methyl, ethyl, or arylsulfones but may be
extended to functionalized sulfonyl cyanides (e.g., 5o−q), albeit
with lower efficiency. Interestingly, these mild conditions also
prevent desulfonylation of the alkanesulfonyl radical and
formation of the corresponding alkyl radical.
(
determined at low conversion using 334 nm monochromatic
irradiation; see SI). The same reaction conducted in the
presence of p-anisaldehyde afforded a 1.8-fold increase in
product yield. Because 4a absorbs at the excitation wavelength,
the observed yield must be corrected for the background
reaction and internal filter effects, providing a value of 0.96 for
the quantum yield of formation of 5b from excited p-
anisaldehyde (see SI). A value close to unity implies that the
sequence of reactions leading to the formation of 5b is
particularly efficient or that it may involve a radical chain
reaction with a turnover >1. Importantly, the transformation is
intrinsically 10-fold faster when sensitized versus direct
irradiation. This, combined with a clean photochemical process,
allows the reaction to be conducted on a multigram scale using
small solvent volumes. Our results suggest that energy transfer
Our efforts were then directed toward the functionalization of
these highly substituted cyclobutanes, first focusing on the
23
opening of the four-membered ring. This strategy would open
an access to enantiopure nitriles γ to a carbonyl group and
bearing an all-carbon quaternary stereocenter (III, Scheme 1),
through an indirect cyanation approach, which complements the
usual cyanations in α and β positions. The regioselective ring
opening was performed through a ketyl radical, generated from
21
22
from the p-anisaldehyde or BP triplet excited state to
RSO CN allows the formation of the sulfonylcyanide excited
2
triplet, which undergoes homolytic cleavage of the O S−CN
N-acyloxazolidinones 5 using SmI , the ensuing fast cyclobutyl
2
2
4
−1 24
bond. The electrophilic sulfonyl radical thus formed would then
add onto the less substituted end of the cyclobutene double
bond to generate a β-sulfonyl radical, finally trapped by
RSO CN, leading to the product and the RSO radical, ready
radical anion ring opening (k ∼ 3 × 10 s ), leading to a
stabilized radical α to the sulfone. Although the generation of a
ketyl radical from amides or N-acyloxazolidinones remains
25
challenging and less documented than for ketones, reduction
2
2
to sustain the radical chain reaction (SI).
and fragmentation was found to proceed in less than 1 h at −78
26
The scope of the sulfonylcyanation was then established using
Eosin-Y (method A) or p-anisaldehyde (method B) as
photosensitizers for comparison purposes. Overall, reactions
were cleaner with method B, easier to carry out, and led to higher
°C using a 1:3 SmI −H O mixture and 4 equiv of SmI (for
2
2
2
optimization, see Tables S3 and S4). Reaction conditions were
shown to tolerate functionalized alkyl groups, aryl groups,
chlorides, protected alcohols, and ethers and led generally to
C
DOI: 10.1021/acs.orglett.9b04345
Org. Lett. XXXX, XXX, XXX−XXX

Organic Letters
Letter
better yields with methylsulfones (e.g., 6n vs 6o) (Scheme 4).
Finally, large-scale synthesis is allowed, as exemplified by the
preparation of nitrile 6e in excellent yield on a 5 mmol scale.
fragment approached anti relative to the bulkier alkyl chain.
Steric differentiation between the linear CN group and any other
substituent on the quaternary stereocenter is noteworthy as it
allows a high level of stereocontrol during the conjugate
addition. Finally, ozonolysis of 7a led to the sensitive
Scheme 4. SmI -Mediated Cyclobutane Ring Opening of
2
2
9
tricarbonylated compound 10, further highlighting the
synthetic potential of these polyfunctionalized cyclobutenes.
In summary, we report in this paper an unprecedented p-
anisaldehyde-photosensitized sulfonylcyanation of cyclobu-
tenes, affording the corresponding cyanosulfones in high yields
and diastereocontrol. An efficient synthesis of enantiopure
cyclobutenes was also disclosed. This study demonstrates that
highly electrophilic sulfonyl radicals can add efficiently to poorly
reactive cyclobutenes. The sequence can be carried out on a
multigram scale with excellent reproducibility, affording
enantiopure cyclobutanes which can then be elaborated further
through ring opening or sulfonyl group elimination. Studies are
now ongoing to exploit further the radical chemistry of these
cyclobutenes for applications in total synthesis of natural
products.
Cyclobutanes 5a−q
ASSOCIATED CONTENT
■
*
S
Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.orglett.9b04345.
Full experimental procedures, characterization data and
copies of NMR spectra for all new compounds (PDF)
Accession Codes
Cyclobutanes such as 5d and 5f were also functionalized
further, relying on the easy removal of the alkanesulfonyl group
Scheme 5). One-pot elimination of the oxazolidinone and
CCDC 1925745, 1934862, and 1935487 contain the supple-
mentary crystallographic data for this paper. These data can be
obtained free of charge via www.ccdc.cam.ac.uk/data_request/
cif, or by emailing data_request@ccdc.cam.ac.uk, or by
contacting The Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
(
Scheme 5. Further Functionalization of Cyclobutanes 5d and
5
f
AUTHOR INFORMATION
■
Corresponding Author
*
E-mail: yannick.landais@u-bordeaux.fr.
ORCID
Iman Traboulsi: 0000-0002-6885-6214
Step
́
hane Massip: 0000-0001-5270-2061
Dario M. Bassani: 0000-0002-9278-1857
ic Robert: 0000-0003-2469-2067
Freder
́ ́
Yannick Landais: 0000-0001-6848-6703
Author Contributions
§V.P. and I.T. contributed equally.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
2
7
sulfonyl groups in 5d and 5f under mild basic conditions thus
provided access to homochiral cyclobutenes 7a,b, ready for
further manipulations. For instance, conjugate addition of
pyrrolidine to 7b furnished the tetra-substituted cyclobutane 9
V.P. (UBx) and I.T. (UBx) thank, respectively, the “Fondation
pour le dev
́
eloppement de la Chimie des substances Naturelles
et ses applications” and the University of Bordeaux for PhD
grants. Ms. A. Buol (UBx) is acknowledged for preliminary
studies. The CNRS and the University of Bordeaux are thanked
for financial help. We acknowledge the analytical facilities
CESAMO for NMR, mass spectrometry, and XRD studies.
28
in high yield and excellent diastereocontrol. Nitromethane
under basic conditions was also shown to add readily to 7a,
providing 8 in 69% yield. In both cases, the nucleophilic
D
DOI: 10.1021/acs.orglett.9b04345
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Organic Letters
Letter
2
012, 3, 1589. (e) Cui, X.; Xu, X.; Lu, H.; Zhu, S.; Wojtas, L.; Zhang, X.
REFERENCES
■
P. J. Am. Chem. Soc. 2011, 133, 3304.
(
2
1) (a) Chen, D. Y.-K.; Pouwer, R. H.; Richard, J.-A. Chem. Soc. Rev.
012, 41, 4631. (b) Wessjohann, L. A.; Brandt, W.; Thiemann, T.
Chem. Rev. 2003, 103, 1625. (c) Namyslo, J. C.; Kaufmann, D. E. Chem.
Rev. 2003, 103, 1485. (d) Lee-Ruff, E.; Mladenova, G. Chem. Rev. 2003,
03, 1449. (e) Seiser, T.; Saget, T.; Tran, D. N.; Cramer, N. Angew.
Chem., Int. Ed. 2011, 50, 7740. (f) Hansen, T. V.; Stenstrøm, Y.
Naturally Occurring Cyclobutanes. In Organic Synthesis: Theory and
Applications; Hudlicky, T., Ed.; Elsevier: Oxford, 2001; Vol. 5, p 1.
(
(
(
12) Zhang, F.-G.; Marek, I. J. Am. Chem. Soc. 2017, 139, 8364.
13) Sakai, K.; Kochi, T.; Kakiuchi, F. Org. Lett. 2013, 15, 1024.
14) (a) Evans, D. A.; Black, W. C. J. Am. Chem. Soc. 1993, 115, 4497.
(
b) Evans, D. A.; Trotter, B. W.; Cote, B.; Coleman, P. J. Angew. Chem.,
Int. Ed. Engl. 1997, 36, 2741.
15) Chatgilialoglu, C.; Mozziconacci, O.; Tamba, M.; Bobrowski, K.;
1
(
Kciuk, G.; Bertrand, M. P.; Gastaldi, S.; Timokhin, V. I. J. J. Phys. Chem.
A 2012, 116, 7623.
(
g) Nakamura, M.; Chi, Y.-M.; Yan, W.-M.; Yonezawa, A.; Nakasugi, Y.;
(
16) (a) Pirenne, V.; Kurtay, G.; Voci, S.; Bouffier, L.; Sojic, N.;
Robert, F.; Bassani, D. M.; Landais, Y. Org. Lett. 2018, 20, 4521.
b) Sun, J.; Li, P.; Guo, L.; Yu, F.; He, Y.-P.; Chu, L. Chem. Commun.
018, 54, 3162.
17) Arceo, E.; Montroni, E.; Melchiorre, P. Angew. Chem., Int. Ed.
014, 53, 12064.
18) (a) Albini, A. Synthesis 1981, 1981, 249. (b) Lu, Z.; Yoon, T. P.
Yoshizawa, T.; Hashimoto, F.; Kinjo, J.; Nohara, T.; Sakurada, S. Planta
Med. 2001, 67, 114. (h) Lee, F.-P.; Chen, Y.-C.; Chen, J.-J.; Tsai, I.-L.;
Chen, I.-S. Helv. Chim. Acta 2004, 87, 463. (i) Liu, R.; Zhang, M.;
Wyche, T. P.; Winston-McPherson, G. N.; Bugni, T. S.; Tang, W.
Angew. Chem., Int. Ed. 2012, 51, 7503.
2) (a) Cavitt, M. A.; Phun, L. H.; France, S. Chem. Soc. Rev. 2014, 43,
04. (b) Schneider, T. F.; Werz, D. B. Org. Lett. 2011, 13, 1848.
c) Schneider, T. F.; Kaschel, J.; Werz, D. B. Angew. Chem., Int. Ed.
014, 53, 5504.
3) For selected reports on the synthesis of cyclopropanes, see:
a) Lebel, H.; Marcoux, J.-F.; Molinaro, C.; Charette, A. B. Chem. Rev.
003, 103, 977. (b) Ebner, C.; Carreira, E. M. Chem. Rev. 2017, 117,
1651. For selected reports on the synthesis of cyclobutanes, see:
c) Poplata, S.; Troster, A.; Zou, Y.-Q.; Bach, T. Chem. Rev. 2016, 116,
̈
748. (d) Misale, A.; Niyomchon, S.; Maulide, N. Acc. Chem. Res. 2016,
9, 2444. (e) Xu, Y.; Conner, M. L.; Brown, M. K. Angew. Chem., Int. Ed.
015, 54, 11918. (f) Luparia, M.; Oliveira, M. T.; Audisio, D.; Frebault,
F.; Goddard, R.; Maulide, N. Angew. Chem., Int. Ed. 2011, 50, 12631.
g) Fawcett, A.; Biberger, T.; Aggarwal, V. K. Nat. Chem. 2019, 11, 117.
h) Andersen, C.; Ferey, V.; Daumas, M.; Bernardelli, P.; Guerinot, A.;
(
2
(
2
(
8
(
2
(
Angew. Chem., Int. Ed. 2012, 51, 10329. (c) Farney, E. P.; Yoon, T. P.
Angew. Chem., Int. Ed. 2014, 53, 793. (d) Alonso, R.; Bach, T. Angew.
Chem., Int. Ed. 2014, 53, 4368.
(19) UV-mediated sulfonylcyanation of olefins was reported earlier,
but the olefin was used as a cosolvent. See: Pews, R. G.; Evans, T. E. J.
Chem. Soc. D 1971, 1397.
(20) Sulfonylcyanation of n-octene using 9,10-dimethylanthracene, a
strong electron donor, but with a low triplet energy, led to the formation
of the desired nitrile with Φ = 0.13 (λ = 365 nm) (SI).
̈
(21) Gorner, H.; Kuhn, H. J. J. Phys. Chem. 1986, 90, 5946.
(22) (a) Yang, N. C.; Kimura, M.; Eisenhardt, W. J. Am. Chem. Soc.
1973, 95, 5058. (b) Koyanagi, M.; Goodman, L. J. Chem. Phys. 1971,
55, 2959.
(23) Kakiuchi, K.; Minato, K.; Tsutsumi, K.; Morimoto, T.; Kurosawa,
H. Tetrahedron Lett. 2003, 44, 1963.
(24) Tanko, J. M.; Phillips, J. P. J. Am. Chem. Soc. 1999, 121, 6078.
(25) (a) Kagan, H. B.; Namy, J. L. In Topics in Organometallic
Chemistry, Lanthanides: Chemistry and Use in Organic Synthesis;
Kobayashi, S., Ed.; Springer: Berlin, 1999; p 155. (b) Procter, D. J.;
Flowers, R. A., II; Skrydstrup, T. Organic Synthesis Using Samarium
Diiodide: A Practical Guide; RSC Publishing, 2010.
(
(
2
1
(
9
4
2
ex
(
(
́
Cossy, J. Org. Lett. 2019, 21, 2285.
4) (a) Rubin, M.; Rubina, M.; Gevorgyan, V. Chem. Rev. 2007, 107,
117. (b) Zhu, Z.-B.; Wei, Y.; Shi, M. Chem. Soc. Rev. 2011, 40, 5534.
c) Vicente, R. Synthesis 2016, 48, 2343. (d) Dian, L.; Marek, I. Angew.
Chem., Int. Ed. 2018, 57, 3682. (e) Didier, D.; Delaye, P.-O.; Simaan,
M.; Island, B.; Eppe, G.; Eijsberg, H.; Kleiner, A.; Knochel, P.; Marek, I.
Chem. - Eur. J. 2014, 20, 1038. (f) Zhang, F.-G.; Eppe, G.; Marek, I.
Angew. Chem., Int. Ed. 2016, 55, 714. (g) Roy, S. R.; Didier, D.; Kleiner,
(
3
(
(
26) (a) Szostak, M.; Spain, M.; Eberhart, A. J.; Procter, D. J. J. Am.
Chem. Soc. 2014, 136, 2268. (b) Hansen, A. M.; Lindsay, K. B.;
Sudhadevi Antharjanam, P. K.; Karaffa, J.; Daasbjerg, K.; Flowers, R. A.;
Skrydstrup, T. J. Am. Chem. Soc. 2006, 128, 9616.
A.; Marek, I. Chem. Sci. 2016, 7, 5989. (h) Mu
Soc. Rev. 2016, 45, 4552.
5) Roy, S. R.; Eijsberg, H.; Bruffaerts, J.; Marek, I. Chem. Sci. 2017, 8,
34.
6) Ferjanci
979.
7) (a) Yamago, S.; Ejiri, S.; Nakamura, E. Chem. Lett. 1994, 23, 1889.
b) Legrand, N.; Quiclet-Sire, B.; Zard, S. Z. Tetrahedron Lett. 2000, 41,
̈
ller, D. S.; Marek, I. Chem.
(
3
(
2
(
(
9
(
27) Simpkins, N. S. Sulphones in Organic Synthesis, Tetrahedron
̌
̌
c, Z.; Cekovic, Z.; Saicic, R. N. Tetrahedron Lett. 2000, 41,
̌ ́ ́ ̌ ́
Organic Chemistry Series; Baldwin, J. E., Magnus, P. D., Eds.;
Pergamon Press: Oxford, 1993, Vol. 10, p 262.
(
28) (a) Johnson, C. R.; De Jong, R. L. J. Org. Chem. 1992, 57, 594.
b) Dowling, M. S.; Vanderwal, C. D. J. Org. Chem. 2010, 75, 6908.
29) Jung, M. E.; Deng, G. J. J. Org. Chem. 2012, 77, 11002.
(
(
815. (c) Ueda, M.; Doi, N.; Miyagawa, H.; Sugita, S.; Takeda, N.;
Shinada, T.; Miyata, O. Chem. Commun. 2015, 51, 4204. (d) Doi, N.;
Takeda, N.; Miyata, O.; Ueda, M. J. Org. Chem. 2016, 81, 7855.
(
8) (a) Kimoto, H.; Muramatsu, H.; Inukai, K. Bull. Chem. Soc. Jpn.
977, 50, 2815. (b) Kinney, W. A. Tetrahedron Lett. 1993, 34, 2715.
c) Leigh, W. J.; Zheng, K.; Nguyen, N.; Werstiuk, N. H.; Ma, J. J. Am.
Chem. Soc. 1991, 113, 4993.
1
(
(
(
9) Dange, N. S.; Robert, F.; Landais, Y. Org. Lett. 2016, 18, 6156.
10) (a) Narasaka, K.; Hayashi, Y.; Shimadzu, H.; Niihata, S. J. Am.
Chem. Soc. 1992, 114, 8869. (b) Schotes, C.; Mezzetti, A. Angew. Chem.,
Int. Ed. 2011, 50, 3072. (c) Kang, T.; Ge, S.; Lin, L.; Lu, Y.; Liu, X.;
Feng, X. Angew. Chem., Int. Ed. 2016, 55, 5541. (d) Kumar, R.; Tamai,
E.; Ohnishi, A.; Nishimura, A.; Hoshimoto, Y.; Ohashi, M.; Ogoshi, S.
Synthesis 2016, 48, 2789. (e) Garcia-Morales, C.; Ranieri, B.; Escofet, I.;
Lopez-Suarez, L.; Obradors, C.; Konovalov, A. I.; Echavarren, A. M. J.
Am. Chem. Soc. 2017, 139, 13628.
(
11) (a) Protopopova, M. N.; Doyle, M. P.; Muller, P.; Ene, D. G. J.
̈
Am. Chem. Soc. 1992, 114, 2755. (b) Lou, Y.; Horikawa, M.; Kloster, R.
A.; Hawryluk, N. A.; Corey, E. J. J. Am. Chem. Soc. 2004, 126, 8916.
(
c) Goto, T.; Takeda, K.; Shimada, N.; Nambu, H.; Anada, M.; Shiro,
M.; Ando, K.; Hashimoto, S.-I. Angew. Chem., Int. Ed. 2011, 50, 6803.
d) Boruta, D. T.; Dmitrenko, O.; Yap, G. P. A.; Fox, J. M. Chem. Sci.
(
E
DOI: 10.1021/acs.orglett.9b04345
Org. Lett. XXXX, XXX, XXX−XXX