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Page 10 of 20 Wang et al. Chem Synth 2023;3:12 https://dx.doi.org/10.20517/cs.2023.01

Figure 12. Catalytic asymmetric [4 + 1] cyclization reaction of sulfonium ylides with the in situ generated ortho-quinone methides. This
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figure is used with permission from the Wiley-VCH Verlag .
However, probably due to the relatively less reactive and low nucleophilicity of carbanion by comparing
with their sulfonium ylide counterparts, significant progress on sulfoxonium ylides-involved asymmetric
reaction by organocatalysis is far lagging behind, although transition-metal catalytic asymmetric
transformations were reported from 2007 [63-67] . Likewise, in this section, the organocatalytic asymmetric
reaction of sulfoxonium ylides will also be discussed in two parts, including the X-H (X = S, N, C) bond
insertion reaction and cyclization reaction.

Asymmetric X-H (X = S, N, C) bond insertion reaction
In 2016, Burtoloso and coworkers reported a catalyst-free S-H bond insertion reaction of sulfoxonium
ylides into aryl thiols, which exhibits a broad substrate scope and high yields for the direct synthesis of β-
keto thioethers under mild reaction conditions . By the year 2020, Burtoloso, Mattson and co-workers
[68]
realized an enantioselective S-H bond insertion reaction of α-carbonyl sulfoxonium ylides to a diverse array
of aryl thiols by taking advantage of a known thiourea catalyst C12 to control the enantioselectivity
[Figure 13] . Under the influence of C12, the asymmetric reaction also shows a relatively broad substrate
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scope, furnishing 2-thioacetate derivatives 52 in excellent levels of enantiocontrol (up to 95% ee) and yields
(up to 97%). Additional investigations on the mechanism indicate that the bonding interactions between the
thiourea moiety of C1 and the S = O functional group of sulfoxonium ylides 50 play a key role in
determining the enantioselectivity. In addition, a plausible reaction pathway was proposed, that is, the chiral
thiourea catalyst C12 incorporates sulfoxonium ylide 50 by hydrogen bond to form complex 53.
Deprotonation of thiophenol 51 with complex 53 forms ion pair 54. And then, the thiolate undergoes a
substitution reaction to give rise to the corresponding product 52 and release chiral thiourea C12
concurrently.

α-Amino esters as versatile building blocks have significant applications in organic synthesis as well as
[70]
widespread distribution in complex natural products, biomolecules and clinically used drugs . Thereby
remarkable achievements have been made in the development of various asymmetric methods for the
[71]
construction of optically pure α-imino esters . Indeed, the asymmetric N-H insertion reactions of α-
carbonyl sulfoxonium ylides to amines are able to provide direct access to chiral α-amino esters. In 2021,
Furniel et al. reported the first asymmetric reaction of α-carbonyl sulfoxonium ylides and anilines by using a
copper-bifunctional squaramide cooperative catalysis strategy, which undergoes an asymmetric N-H
insertion process to afford a series of chiral α-aryl glycine esters 5 in good to excellent yields and