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Wu et al. Chem Synth 2023;3:6 https://dx.doi.org/10.20517/cs.2022.42 Page 11 of 17

Scheme 5. Preparation of (Sa)-3aa and (Ra)-3aa by the strategy of chiral resolution.

CONCLUSION
In summary, by changing the alkynyl terminal substituent from t-Bu to an aryl group, the reactivity of 3-
alkynyl-2-indolylmethanols was modulated as competent platform molecules for Brønsted acid-catalyzed
Nazarov-type cyclization. Based on this new reactivity, we accomplished the first organocatalytic Nazarov-
type cyclization of aryl-substituted 3-alkynyl-2-indolylmethanols with 2-naphthols, thus realizing the
efficient construction of a new class of axially chiral 3, 4-dihydrocyclopenta[b]indole scaffolds. The
preliminary investigation on the organocatalytic asymmetric Nazarov-type cyclization provided an optional
strategy for atroposelective construction of this new class of axially chiral cyclopenta[b]indole scaffolds. In
addition, we realized the first preparation of axially chiral 3, 4-dihydrocyclopenta[b]indoles with optical
purity by the strategy of chiral resolution, which could serve as a complementary method to catalytic
asymmetric approaches. This work will not only add new contents to the chemistry of Nazarov-type
cyclization and indolylmethanols, but also contribute to the research field of constructing axially chiral
indole-based scaffolds via asymmetric organocatalysis.

DECLARATIONS
Acknowledgments
We sincerely thank all the group members who are involved in the development of new kinds of
indolylmethanols as platform molecules.

Authors’ contributions
Performing the majority of the experiments: Wu P
Doing some of the experiments: Yan XY, Jiang S
Initially trying the model reaction: Lu YN
Co-directing this project and writing the draft manuscript: Tan W
Directing this project and revising the manuscript: Shi F

Availability of data and materials
Supplementary Materials are available online for this paper.

Financial support and sponsorship
We thank National Natural Science Foundation of China (22125104 and 21831007), Natural Science
Foundation of Jiangsu Province (BK20210916) and High Education Natural Science Foundation of Jiangsu