Synfacts 2019; 15(01): 0033
DOI: 10.1055/s-0037-1611452
Synthesis of Materials and Unnatural Products
© Georg Thieme Verlag Stuttgart · New York

Endo, Exo, and What?

Timothy M. Swager
Samuel I. Etkind
Lu Y, Qiao Y, Xue H, Zhou G. * Fudan University, Shanghai, P. R. of China
From Colorless to Near-Infrared S-Heteroarene Isomers: Unexpected Cycloaromatization of Cyclopenta[b]thiopyran Catalyzed by PtCl2 .

Org. Lett. 2018;
20: 6632-6635
Further Information

Publication History

Publication Date:
14 December 2018 (online)



The properties of cyclopenta[b]thiopyran and derivatives thereof are largely unexplored, due in part to their challenging synthesis. This methodology, however, provides rapid access to many thiopyran derivatives. Thiopyran 4, being isoelectronic to azulene, exhibits many interesting properties, such as strong near-IR absorption and exceptional electrochemical stability, as observed by cyclic voltammetry studies.



The ability to transform a single compound into a multitude of products with unique properties is particularly useful for the synthesis of functional materials. In this report, the authors cyclize diyne 1 to form 2 via a 6-endo cyclization, 3 via a 5-exo cyclization, and 4 via an unexpected skeletal rearrangement.