Abstract
A crude morpholine enamine of acetone treated with Lawesson’s reagent unexpectedly yielded a six-membered thiaphosphinane-4-one. This compound is the first example of a new class of heterocycles. It has been proven that it is formed from 4-methyl-2-morpholino-1,3-pentadiene which is usually present in crude morpholine enamine batches. A mechanism of this regioselective reaction was postulated and a characteristic chair-like conformation of the product was examined in detail. Additionally, some unusual primary fragmentations of the product with the loss of H2S and isobutylene were observed for positive and negative ESI ionization mode, respectively.
Graphical abstract
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Acknowledgments
We thank Professor Jarosław Chojnacki for carrying out single-crystal X-ray diffraction analysis for compound 3. The financial support to maintenance of research facilities used in these studies from Gdańsk University of Technology by the DEC–2/2021/IDUB/V.6/Si grant under the Silicium Supporting Core R&D Facilities – “Excellence Initiative – Research University” program is gratefully acknowledged.
Disclosure statement
No potential conflict of interest was reported by the author(s).