What question did this study set out to answer?

To isolate and characterize a spiro compound derived from the reaction of aldehydes.

January 6, 2026Molbank0 citationsOpen Access

(RS)-6,6,7′,7′-Tetramethyl-2-sulfanylidene-5,6,6′,7′-tetrahydro-2H,2′H,4H,4′H,5′H-spirothiopyran-3,3′-thiopyrano [2,3-bthiopyran]-4,5′-dione

WSWerner SeebacherUniversity of Graz ADAntoine DupéUniversity of Graz PEPferschy-Wenzig Eva-MariaUniversity of Graz

Key Points

To isolate and characterize a spiro compound derived from the reaction of aldehydes.
Isolated spiro compound through modified reaction conditions with formaldehyde.
Characterization performed using X-ray crystal analysis and various NMR techniques.
Successfully isolated (RS)-6,6,7′,7′-Tetramethyl-2-sulfanylidene-5,6,6′,7′-tetrahydro-2H,2′H,4H,4′H,5′H-spiro[thiopyran-3,3′-thiopyrano [2,3-b]thiopyran]-4,5′-dione for the first time.
Structure confirmed via X-ray crystal analysis and characterized with NMR and IR measurements.

Abstract

The reaction of aliphatic aldehydes with the tautomers 6,6-dimethyl-4-hydroxy-2H-thiopyrane-2-thione and 6,6-dimethyl-2-mercapto-4H-thiopyrane-4-one is reported to yield spiro compounds. However, the spiro compound of the reaction with formaldehyde is postulated, but has not been isolated to date. Due to a change in reaction conditions, we managed to isolate (RS)-6,6,7′,7′-Tetramethyl-2-sulfanylidene-5,6,6′,7′-tetrahydro-2H,2′H,4H,4′H,5′H-spirothiopyran-3,3′-thiopyrano [2,3-bthiopyran]-4,5′-dione for the first time. The structure was proven with the help of a single X-ray crystal analysis. Furthermore, the new compound was fully characterized using one- and two- dimensional NMR techniques such as 1H, 13C, DEPT, COSY, HSQC and HMBC spectra, as well as IR and HRMS measurements.

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