First synthesis of ferrocenyl-substituted thiochalcones and their [4+2]-cycloadditions with acetylenic dienophiles

ABSTRACT

Ferrocenyl methyl ketone reacts with aromatic aldehydes yielding 1-ferrocenyl-3-aryl-propenones (chalcones), which upon treatment with Lawesson’s reagent (LR) are converted to the corresponding thiochalcones. The latter enter the thia-Diels–Alder reaction with acetylenic dienophiles (DMAD and methyl propiolate) to give ferrocenyl-substituted 4H-thiopyrans. In the case of methyl propiolate, the formation of the six-membered ring occurs with complete regioselectivity.

GRAPHICAL ABSTRACT

KEYWORDS:

• Ferrocenyl derivatives
• chalcones
• thiochalcones
• hetero-Diels–Alder reactions
• 4H-thiopyrans

Acknowledgements

Skillful performance of elemental analysis of all new compounds by Ms Agnieszka Cieślińska and Ms Hanna Jatczak (University of Łódź) is gratefully acknowledged.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Authors thank the National Science Center (Cracow, Poland) for generous financial support (Grant Maestro-3; Dec-2012/06/A/ST5/00219). G.M. and R. H.-F. acknowledge also the Alexander von Humboldt Stiftung (Bonn, Germany) for financial support within the ‘Institutspartnerschaft’ project (2018–2020).