Photochemical, Metal-Free Sigmatropic Rearrangement Reactions of Sulfur Ylides

Article abstract of DOI:10.1002/chem.201900597

Sigmatropic rearrangement reactions constitute one of the most fundamental reactions of carbenes. While state-of-the-art synthetic methods require the use of expensive precious metal catalysts, the application of visible light for the photolysis of α-aryldiazoacetates is much less investigated and provides an operationally simple entry to carbenes under mild reaction conditions. Herein, we report on blue-light induced sigmatropic rearrangement reactions of sulfur compounds with α-aryldiazoacetates. This process, depending on the substitution pattern of the sulfide, opens up formal insertion reactions of carbenes into S?N, S?C, or C?H bonds.

Full text of DOI:10.1002/chem.201900597

A Journal of
Accepted Article
Title: Photochemical, metal-free sigmatropic rearrangement reactions
of sulfur ylides
Authors: Zhen Yang, Yujing Guo, and Rene M. Koenigs
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To be cited as: Chem. Eur. J. 10.1002/chem.201900597
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10.1002/chem.201900597
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COMMUNICATION
Photochemical, metal-free sigmatropic rearrangement reactions
of sulfur ylides
Zhen Yang,[a] Yujing Guo,[a] and Rene M. Koenigs*[a]
Abstract: Sigmatropic rearrangement reactions constitute one of the
most fundamental reactions of carbenes. While state-of-the-art
This work
synthetic methods require the use of expensive precious metal
blue light
(470 nm)
sigmatropic rearrangements
broad substrate scope
chemoselective
metal-free
operationally simple
Ar'
Ar
R
N2
catalysts, the application of visible light for the photolysis of
α-aryldiazoacetates is much less investigated and provides an
operationally simple entry to carbenes under mild reaction conditions.
Herein, we report on blue light induced sigmatropic rearrangement
reactions of sulfur compounds with α-aryldiazoacetates. This
process, depending on the substitution pattern of the sulfide, opens
up formal insertion reaction of carbenes into S-N, S-C or C-H bonds.
S
Ar
EWG
S
EWG
Ar'
R
free ylide
S
CO2Et
EWG
Ar'
Ar'
Ar
S
Ar''
EWG
O
Ar'
Ar
S
N
O
EWG
[1,2]-sigmatropic
rearrangement
Stevens
rearrangement
Sommelet-Hauser
rearrangement
The application of visible light in organic synthesis has received
tremendous interest in the past decade and has evolved to a
powerful tool to conduct a broad variety of photochemical[1] and
photocatalytic[2] transformations and enables a rich portfolio of
chemical transformations that is primarily based on radical
chemistry.[2,3] Although the photochemical transfer of
electrophilic, electronically unsaturated carbenes is known since
the 1950’s using high-energy UV-light,[4] chemical applications
remained scarce due to low-yielding transformations and side
reactions caused by the strong UV-light.[4,5] Only recently, the
application of visible light caught the attention of synthetic
organic chemists[6-8] and a few initial applications by the Davies
group,[8a] He and-coworkers,[8b] Lu, Xiao et al.[8c] and our
group[8d] reported on the use of blue light in carbene transfer
reactions to conduct cyclopropa(e)nation, X-H insertion,
olefination or Doyle-Kirmse rearrangement reactions.[8,9]
Scheme 1. Photochemical sigmatropic rearrangement reactions.
We became intrigued in studying metal-free [1,2]-sigmatropic
rearrangement reactions using blue light to generate carbenes
from α-aryldiazoacetates (Scheme 1). We initiated our
investigations by studying the reaction of phenyl diazoacetate 1
and N-sulfenyl phthalimide
2
under metal-free reaction
conditions and irradiation with blue LEDs. We were delighted to
observe that the S-N insertion product could be isolated in good
yield at ambient temperature and using conventional p.A. grade
solvents und an air atmosphere (Table 1).
The Stevens rearrangement,[10] is well-described with
ammonium ylides and numerous reports showcase the potential
of this formal insertion reaction into carbon-nitrogen bonds
ranging from synthetic methodology, total synthesis to
applications in medicinal chemistry.[11] To date, limited
approaches towards Stevens rearrangement reactions of sulfur
ylides with donor-acceptor diazo derivatives have been reported
that are limited to high temperature processes with precious
metal catalysts and to formal heteroatom-heteroatom insertion
reactions.[12] Moreover, the Stevens rearrangement leading to a
formal insertion of a carbene fragment into a carbon-sulfur bond
is much less investigated and current approaches are limited to
the application of acceptor-only diazoalkanes, yet limited due to
the regioselectivity of competing [1,2]- and [2,3]-sigmatropic
rearrangement process[13a] or to specific, highly reactive
substrates.[13b] To the best of our knowledge, the development of
a highly regioselective Stevens rearrangement reactions of
donor-acceptor carbenes is highly demanded and it would pave
the way towards formal insertion reactions into carbon-sulfur
bonds leading to fully substituted carbon centers.
Table 1. Reaction Optimization.
O
blue light
(470 nm)
N2
O
+
N
S
PhS
N
CO2Me
O
Ph
rt
CO2Me
O
1
2
3a
entry[a]
solvent
yield
changes from standard
conditions
1
2
3
4
5
6
7
THF
-
39%
29%
44%
56%
85%
89%
Toluene
MeCN
DCM
DCM
DCM
DCM
-
-
-
5 eq. 2
10 eq. 2
5 eq. 2, in the dark
no rct.
[a] Reaction conditions: diazoalkane (0.2 mmol) and N-sulfenyl phthalimide (2.0
eq.) were dissolved in 2 mL DCM and irradiated with blue LEDs (470 nm, 3 W)
for 12 h. Yields refer to isolated product.
[a]
Zhen Yang, Yujing Guo, Prof. Dr. Rene M. Koenigs
Institute of Organic Chemistry, RWTH Aachen University
Landoltweg 1, 52074 Aachen, Germany
E-mail: rene.koenigs@rwth-aachen.de
Supporting information for this article is given via a link at the end of
the document.
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10.1002/chem.201900597
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COMMUNICATION
Different polar and apolar solvents were compatible and the
reaction product was obtained in moderate yield, only in
chloroform and hexane no reaction was observed. While the
missing reactivity in hexane can be explained by the low
solubulity of N-sulfenyl phthalimide in hexane and thus
dimerization of the α-aryldiazoacetates, the outcome in
chloroform solvent can be rationalized by reaction of the
carbene intermediate with solvent molecules.[14,15] Under optimal
conditions (table 1, entry 6), we were able to isolate the desired
different α-aryldiazoacetates and N-sulfenyl phthalimides in this
[1,2]-sigmatropic rearrangement reaction. Halogens (3f, 3g, 3h,
3j, 3q, 3u), ethers (3e, 3i, 3s, 3t) and aliphatic (3n, 3o, 3p, 3r)
substituents at the phenyl ring as well as different carbocycles
(3k, 3l, 3m) had only little influence on the reaction outcome and
the product of the [1,2]-rearrangement could be isolated in up to
95% yield in case of meta- or para-substitution pattern on both
reaction partners. The introduction of an ortho-substituent
resulted in slightly reduced yields of the rearrangement product,
α-mercapto ester 3a in very good yield.[16] In the absence of light, which might be attributed to steric hindrance of the
no reaction was observed (Table 1, entry 7).
rearrangement process due to the high steric demand of
With the optimal conditions in hand, we next studied the
applicability of this transformation and studied the reaction of
substituents involved in the rearrangement process (3j, 3t, 3u).
O
blue light
(470 nm)
O
N2
ArS
Ar'
S
Ar'
+
Ar
N
S
Ar'S
N
Ar
EWG
DCM
rt
O
Ar
CO2Me
Ar'
Ar
EWG
3a-u
[1,2]-sigmatropic rearrangement products
O
1
2, 5 eq.
4, 5 eq.
5a-v
diazoalkane
N-sulfenyl phthalimides benzylic sulfides
a) [1,2]-sigmatropic rearrangements of sulfenyl phthalimides
O
PhS
O
O
O
O
PhS
N
PhS
N
PhS
N
PhS N
N
O
O
O
O
R
O
EWG
CO2Me
CO2Me
CO2Me
CO2Me
O
3a, EWG = CO2Me 85%
3b, EWG = CO2Et 56%
3c, EWG = CO2Bn 87%
3e, R = 4-OEt 67%
3k, 53%
3l, 67%
3m, 74%
O
3f, R = 4-F
75%
64%
57%
3g, R = 4-Cl
3d, EWG = CF3
no rct. 3h, R = 4-Br
3i, R = 3-OMe 72%
3j, R = 2-F
38%
b) Stevens rearrangement of benzylic sulfides
R
PhS
Ph
O
PhS
Ph
O
O
R
S
N
EWG
R
S
N
S
N
CO2Me
O
O
O
Ph
CO2Me
Ph
CO2Me
Ph
CO2Me
R
3n, R = Me 81%
3o, R = Et 90%
3p, R = tBu 95%
3q, R = Cl 62%
3r, R = Me 80%
3s, R = OMe 81%
3t, R = MeO 43%
5a, EWG = CO2Me 76%
5b, EWG = CO2Et 68%
5c, R = 4-F
5d, R = 4-Cl
5e, R = 4-Br
5f, R = 3-Cl
64%
3u, R = F
50%
55%
71%
80%
5g, R = 3-MeO 58%
5h, R = 2-Cl
5i, R = 2-F
77%
61%
S
R
PhS
Ph
CO2Me
PhS
Ph
S
Ph
R
S
Ph
PhS
O
CO2Me
Ph
CO2Me
Ph
CO2Me
Ph
CO2Me
O
5k, 51%
5l, R = F
5m, R = Cl
5n, R = CN
40%
53%
50%
5p, 27%
5q, R = 4-NO2
5r, R = 4-Br
5s, R = 2-Me
5t, R = 2-Cl
5u, R = 2-Br
5v, R = 2,6-Cl2
66%
56%
78%
82%
50%
75%
5j, 67%
5o, R = NO2 66%
Scheme 2. Investigation on [1,2]-sigmatropic rearrangement reactions. Reaction conditions: sulfide (2 or 4) (5 eq.) and diazoalkane (0.2 mmol) were dissolved in
2 mL DCM and irradiated with blue LEDs (470 nm, 3 W) for 12 h. Yields refer to isolated products.
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10.1002/chem.201900597
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COMMUNICATION
Ar
R
Ar
R
To investigate the generality of light-induced
[1,2]-sigmatropic rearrangement reactions, we
next focused on benzylic sulfides, which would
provide an entry into the formal insertion
reaction of a carbene fragment into a C-S bond.
The rearrangement reaction of benzylic
N2
[1,2]-sigmatropic
rearrangement
Stevens reaction
Sommelet Hauser reaction
S
9
470 nm
S
Ph
EWG
Ph
EWG
Ph
EWG
1
18
carbene
free ylide
key intermediate
in photochemical rearrangement
reactions of sulfur ylides
sulfides is particularly challenging (vide supra)
and we were delighted to observe that benzyl
Scheme 4. Mechanistic hypothesis of rearrangement reactions of sulfur ylides.
phenyl sulfides
reacted with a perfect chemoselectivity in a
[1,2]-sigmatropic rearrangement. Different
4 and α-aryldiazoacetates
which is a prerequisite for the subsequent Sommelet-Hauser
rearrangement and rearomatization steps (Scheme 3). Finally,
we investigated a small set of different α-aryldiazoacetates,
substitution patterns with broad functional group tolerance were
tolerated for both coupling partners, including halogens (5c, 5d,
5e, 5f, 5h, 5i, 5l, 5m, 5r, 5t, 5u, 5v), nitro (5o, 5q) or nitrile (5n)
functional groups, and the desired Stevens rearrangement
products were isolated as the sole rearrangement product in
yields of up to 80% (scheme 2b) Similarly, different carbocyclic
diazoesters (5j, 5k) were well tolerated and the corresponding
reaction products were isolated in good yield. Notably, even the
sterically demanding 2,6-dichloro substituted benzylic sulfide
reacted smoothly in this sigmatropic rearrangement reaction (5v).
In all reactions, no products of [2,3]-sigmatropic rearrangement
reaction were observed, as it is the case for acceptor-only diazo
derivative.[13b]
which
smoothly
underwent
this
formal
ortho
C-H
functionalization reaction and the desired reaction products were
isolated in moderate to high yield (Scheme 3, 7a-f).
Based on the above data, we hypothesize that under the
photochemical conditions an electrophilic carbene 18 is
generated, which might be reversibly stabilized by solvent
molecules.[14-15,18] This highly reactive carbene can subsequently
be trapped by sulfur nucleophiles under formation of a free ylide
intermediate 9, which then undergoes, depending on the
substitution pattern, different sigmatropic rearrangement
reactions (Scheme 4).
When switching to the α-mercapto ester 6, we observed a switch
from [1,2]-sigmatropic to [2,3]-sigmatropic rearrangement under
otherwise identical reaction conditions. This observation can be
rationalized by ylide formation followed by tautomerization,
In summary, we herein report on photochemical rearrangement
reactions of sulfides with α-aryldiazoacetates. The photolysis of
α-aryldiazoacetates enables a metal-free access to carbenes
that, upon formation of a free ylide intermediate with sulfur-
based nucleophiles, readily undergo highly chemoselective
rearrangement reactions in up to 95% yield (47 examples). This
photochemical protocol now opens up new and operationally
simple methods for the formal insertion reactions of carbenes
into S-N, S-C or C-H bonds.
S
CO2Et
blue light
(470 nm)
Ph
N2
S
CO2Et
+
EWG
7a-f
Ph
Ar
EWG
DCM
rt
R
6, 5 eq.
mercapto ester
1
diazoalkane
formal C-H functionalization
Sommelet Hauser
rearrangement
ylide
formation
Acknowledgements
EWG
Ar
EWG
tautomerization
S
RMK gratefully acknowledges the Dean’s Seed Fund of RWTH
Aachen University. YG thanks the Chinese Scholarship Council
(CSC No. 201807040083) for generous support.
S
CO2Et
Ph
Ph
CO2Et
S
S
CO2Et
CO2Me
S
CO2Et
CO2Me
S
CO2Et
CO2Me
Ph
Ph
Cl
Ph
Keywords: photochemistry • carbene • diazoalkane •
rearrangement • metal-free
7a, 61%
7b, 43%
7c, 81%
Cl
[1]
Selected articles on photochemical reactions: a) S. Poplata, A. Tröster,
Y.-Q. Zou, T. Bach, Chem. Rev. 2016, 116, 9748-9815; b) R. Remy, C.
G. Bochet, Chem. Rev. 2016, 116, 9816-9849; c) M. D. Kärkäs, J. A.
Porco Jr., C. R. J. Stephenson, Chem. Rev. 2016, 116, 9683-9747; d) T.
P. Nicholls, D. Leonori, A. C. Bissember Nat. Prod. Rep. 2016, 33,
1248-1254.
CO2Et
CO2Et
S
CO2Et
S
CO2Et
CO2Me
Ph
Br
Ph
Ph
CO2Me
Br
F
7d, 40%
7e, 53%
7f, 52%
[2]
[3]
Selected articles on photocatalytic reactions: a) N. A. Romero, D. A.
Nicewicz, Chem. Rev. 2016, 116, 10075-10166; b) L. Marzo, S. K.
Pagire, O. Reiser, B. König, Angew. Chem. Int. Ed. 2018, 57, 10034-
10072; Angew. Chem. 2018, 130, 10188-10228.
Scheme 3. Visible light mediated Sommelet-Hauser rearrangement reactions.
Reaction conditions: diazoalkane (0.2 mmol) and 6 (5.0 Eq.) were dissolved in
2 mL DCM and irradiated with blue LEDs (470 nm, 3 W) for 12 h. Yields refer
to isolated products.
Selected articles on photochemical radical transfer reactions: a) J.
Davies, S. P. Morcillo, J. J. Douglas, D. Leonori, Chem. Eur. J. 2018,
24, 12154-12163; b) M. D. Kärkäs, ACS Catal. 2017, 7, 4999-5022; c)
A. Studer, D. P. Curran, Angew. Chem. Int. Ed. 2016, 55, 58-102;
Angew. Chem. 2016, 128, 58-106.
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COMMUNICATION
[4]
[5]
W. B. DeMore, H. O. Pritchard, N. Davidson, J. Am. Chem. Soc. 1959,
81, 5874-5879.
Hock, R. M. Koenigs, Chem. Commun. 2019, 55, 338-341; g) A. V.
Stepakov, A. P. Molchanov, J. Magull, D. Vidovic, G. L. Starova, J. Kopf,
R. R. Kostikov, Tetrahedron, 2006, 62, 3610-3618; h) J.-P. Qu, Z.-H.
Xu, J. Zhou, C.-L. Cao, X.-L. Sun, L.-X. Dai Y. Tang, Adv. Synth. Catal.
2009, 351, 308-312; i) V. Nair, S. M. Nair, S. Mathai, J. Liebscher, B.
Ziemer, K. Narsimulu, Tetrahedron Lett. 2004, 45, 5759-5762; j) K. K.
Ellis-Holder, B. P. Peppers, A. Y. Kovalesky, S. T. Diver, Org. Lett.
2006, 8, 2511-2514.
Selected references: a) N. R. Candeias, C. A. M. Afonso, Curr. Org.
Chem. 2009, 13, 763-787; b) O. S. Galkina, L. L. Rodina, Russ. Chem.
Rev. 2016, 85, 537-555; c) J. Brunner, H. Senn, F. M. Richards, J. Biol.
Chem. 1980, 255, 3313-3318; d) Y. Liang, L. Jiao, S. Zhang, J. Xu, J.
Org. Chem. 2005, 70, 334-337; e) J. Wang, G. Burdzinski, J. Kubicki, M.
S. Platz, J. Am. Chem. Soc. 2008, 130, 11195-11209; f) K. Nakatani, S.
Maekawa, K. Tanabe, I. Saito, J. Am. Chem. Soc. 1995, 117, 10635-
10644.
[11] a) J. B. Sweeney, Chem. Soc. Rev. 2009, 38, 1027-1038; b) E. Tayama,
Chem. Rec. 2015, 15, 789-900.
[6]
[7]
L. W. Ciszewski, K. Rybicka-Jasińska, D. Gryko, Org. Biomol. Chem.
2019, 17, 432-448.
[12] a) Z. Song, Y. Wu, T. Xin, C. Jin, X. Wen, H. Sun, Q.-L. Xu, Chem.
Commun. 2016, 52, 6079-6082; b) H. Yuan, T. Nuligonda, H. Gao, C.-H.
Tung, Z. Xu, Org. Chem. Front. 2018, 5, 1371-1374; c) Y. Li, Z. Huang,
X. Wu, P. Xu, J. Wang, Y. Zhang, Org. Lett. 2011, 13, 1210-1213.
[13] a) M. Liao, L. Peng, J. Wang, Org. Lett. 2008, 10, 693-696; b) X. Xu, C.
Li, M. Xiong, Z. Tao, Y. Pan, Chem. Commun. 2017, 53, 6219-6222; c)
Y. Huang, X. Li, X. Wang, Y. Yu, J. Zheng, W. Wu, H. Jiang, Chem. Sci.
2017, 8, 7047-7051.
Selected references: (a) Z. Wang, A. G. Herraiz, A. M. del Hoyo, M. G.
Suero, Nature 2018, 554, 86-91. b) Y. S. Mimieux Vaske, M. E.
Mahoney, J. P. Konopelski, D. L. Rogow, W. J. McDonald, J. Am.
Chem. Soc. 2010, 132, 11379-11385.
[8]
a) I. Jurberg, H. M. L. Davies, Chem. Sci. 2018, 9, 5112-5118; b) T.
Xiao, M. Mei, Y. He, L. Zhou, Chem. Commun. 2018, 54, 8865-8868; c)
D. Liu, W. Ding, Q.-Q. Zhou, Y. Wei, L.-Q. Lu, W.-J. Xiao, Org. Lett.
2018, 20, 7278-7282; d) R. Hommelsheim, Y. Guo, Z. Yang, C. Empel,
R. M. Koenigs, Angew. Chem. Int. Ed. 2019, 58, 1203-1207; Angew.
Chem. 2019, 131, 1216-1220; e) S. Jana, R. M. Koenigs, Asian J. Org.
Chem. 2019, DOI: 10.1002/ajoc.201900099.
[14] Photolysis of donor-acceptor complex provides initially
a singlet
carbene, which can be stabilized by solvent molecules. This process
might increase the lifetime of the carbene intermediate. For references,
please see N. J. Turro, Y. Cha, I. R. Gould, J. Am. Chem. Soc. 1987,
109, 2101-2107.
[9]
Selected review articles on metal-catalyzed carbene transfer reactions:
a) A. DeAngelis, R. Panish, J. M. Fox, Acc. Chem. Res. 2016, 49, 115-
127; c) A. Ford, H. Miel, A. Ring, A. N. Slattery, A. R. Maguire, M. A.
McKervey, Chem. Rev. 2015, 115, 9981-10080; d) H. U. Reissig, R.
Zimmer, Chem. Rev. 2003, 103, 1151-1196; e) H. M. L. Davies, J. R.
Manning, Nature 2018, 451, 417-424; f) M. P. Doyle, R. Duffy, M.
Ratnikov, Z. Zhou, Chem. Rev. 2010, 110, 704-724; g) L. Mertens, R.
M. Koenigs, Org. Biomol. Chem. 2016, 14, 10547-10556; h) K. J. Hock,
A. Knorrscheidt, R. Hommelsheim, J. Ho, M. J. Weissenborn, R. M.
Koenigs, Angew. Chem. Int. Ed. 2019, 58, 3630-3634; Angew. Chem.
2019, 131, 3669-3673; i) Y. Xia, D. Qiu, J. Wang, Chem. Rev. 2017,
117, 13810-13889.
[15] M. B. Jones, J. E. Jackson, N. Soundararajan, M. S. Platz, J. Am.
Chem. Soc. 1988, 110, 5597
[16] As comparable yields were obtained with only 5 eq. of N-sulfenyl
phthalimide 2, we decided to continue our investigations with 5 eq. of
the sulfides.
[17] a) Z. Zhang, Z. Sheng, W. Yu, G. Wu, R. Zhang, W.-D. Chu, Y. Zhang,
J. Wang, Nature Chem. 2017, 9, 970-976; b) X. Zhang, Z. Qu, Z. Ma, W.
Shi, X. Jin, J. Wang, J. Org. Chem. 2002, 67, 5621-5625; c) K. J. Hock,
R. M. Koenigs, Angew. Chem. Int. Ed. 2017, 56, 13566-13568; Angew.
Chem. 2017, 129, 13752-13754.
[18] For a discussion of the interconversion of donor acceptor singlet and
triplet carbenes, please see: a) Z. Zhu, T. Bally, L. L. Stracener, R. J.
McMahon, J. Am. Chem. Soc. 1999, 121, 2863-2874.
[10] a) Z. Sheng, Z. Zhang, C. Chu, Y. Zhang, J. Wang, Tetrahedron 2017,
73, 4011-4022; b) J. D. Neuhaus, R. Oost, J. Merad, N. Maulide, Top.
Curr. Chem. 2018, 376, 15; c) R. Bach, S. Harthong, J. Lacour,
Comprehensive Organic Synthesis II, 2014, 3, 992; d) T. H. West, S. S.
M. Spoehrle, K. Kasten, J. E. Taylor, A. D. Smith, ACS Catal. 2015, 5,
7446-7479; e) K. J. Hock, L. Mertens, R. Hommelsheim, R. Spitzner, R.
M. Koenigs, Chem. Commun. 2017, 53, 6577-6580; f) C. Empel, K. J.
[19] D. Werlé, R. Goddard, A. Fürstner, Angew. Chem. Int. Ed. 2015, 54,
15452-15456; Angew. Chem. 2015, 127, 15672-15676.
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COMMUNICATION
Entry for the Table of Contents
COMMUNICATION
Zhen Yang, Yujing Guo, and Rene M.
Koenigs*
Page No. – Page No.
Photochemical, metal-free
sigmatropic rearrangement reactions
of sulfur ylides
The photolysis of α-aryldiazoacetates enables efficient sigmatropic rearrangement
reactions with sulfides. Depending on the substitution pattern of the sulfide different
rearrangement products can be obtained under metal-free and operationally simple
conditions in an air atmosphere.
This article is protected by copyright. All rights reserved.