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Wang et al. Chem Synth 2023;3:12 https://dx.doi.org/10.20517/cs.2023.01 Page 17 of 20

catalyst, the reaction of benzopyrylium triflate 88 and sulfoxonium ylide 50 gave rise to product 86a in 61%
yield with 48% ee, which could be improved to 74% ee after simple recrystallization.

CONCLUSION AND OUTLOOK
Sulfur-based ylides have been identified and confirmed as versatile reactants for a wide range of chemical
transformations. In this review, organocatalyzed asymmetric reactions involving sulfonium and
sulfoxonium ylides are summarized and reviewed. Due to the eminent characteristics of stabilized
sulfonium and sulfoxonium ylides, such as thermal stability, easy preparation, storage, and use, and low
toxicity, these compounds have drawn great attention from many research groups and are widely used in
various catalytic asymmetric reactions over the past twenty years with the rapid development of
organocatalysis. As to the research on sulfonium ylides, the organocatalyzed enantioselective
transformations mainly focus on the cyclopropanation and [4 + 1] cyclization reaction, and only one report
concerning the N-H bond insertion reaction has been published so far. However, with respect to the
sulfoxonium ylides, synthetic chemists put relatively more research emphasis on the catalytic asymmetric X-
H (X = S, N, C) bond insertion reaction for the C-C and C-X (X = N, S) bond construction, and only one
example about asymmetric cyclization reaction has been reported with organocatalysis at present.

Although a number of reports are available on the application of sulfonium and sulfoxonium ylides in
various asymmetric reactions, there is still a vast space for research on the fast-developing asymmetric
organocatalysis. First of all, since the stabilized sulfur ylides are still limited, more and more newly stabilized
sulfonium or sulfoxonium ylides with more fascinating skeletons should be explored. Second, searching for
a new catalytic system for the application of unstabilized sulfur ylides in the possible asymmetric reaction
should also be investigated. Third, expanding the scopes and sources of reaction partners with sulfur ylides
to develop novel asymmetric reactions for the construction of pharmaceutically valuable molecules with
innovative structures is very necessary. Finally, applying the developed asymmetric organocatalysis
methodology involving sulfonium or sulfoxonium ylides for the efficient synthesis of natural products or
pharmaceutical molecules is also worth pursuing. The main purpose of this review is to disclose the current
situation of organocatalyzed asymmetric reaction of sulfnoium and sulfoxonium ylides, but we would rather
it will provoke further exciting, groundbreaking discoveries soon. In a word, the authors hope this review in
this phase benefits the development of sulfur ylides research area. Moreover, the authors would like to
apologize in advance for any omissions in the literature survey.

DECLARATIONS
Acknowledgments
We sincerely thank all leading chemists and coworkers involved in the development of organocatalyzed
asymmetric reaction of sulfnoium and sulfoxonium ylides.

Authors’ contributions
Wrote the draft manuscript: Wang ZH
Revised the manuscript: Sun TJ, Zhang YP, You Y, Zhao JQ, Yin JQ
Guided this work, revised and rewrote some parts of the manuscript: Yuan WC

Availability of data and materials
Not applicable.

Financial support and sponsorship
We are grateful to the Natural Science Foundation of China (No. 22171029, 21801024, 21901024, 21871252,
21801026, and 22271027), the Sichuan Science and Technology Program (2021YFS0315).