2-(2-(Dimethylamino)vinyl)-4 H -pyran-4-ones as Novel and Convenient Building-Blocks for the Synthesis of Conjugated 4-Pyrone Derivatives

• Published in: Molecules (Basel, Switzerland) Vol. 27; no. 24
• Main Authors: Obydennov, Dmitrii L, Nigamatova, Diana I, Shirinkin, Alexander S, Melnikov, Oleg E, Fedin, Vladislav V, Usachev, Sergey A, Simbirtseva, Alena E, Kornev, Mikhail Y, Sosnovskikh, Vyacheslav Y
• Format: Journal Article
• Language: English
• Published: Switzerland 16.12.2022
• Subjects: Pyrans - chemistry; Pyrones - chemistry; fluorophore; cycloaddition; 4-pyrone; DMF-DMA; 1,6-conjugate addition; merocyanine; enamination; solvatochromism

A straightforward approach for the construction of the new class of conjugated pyrans based on enamination of 2-methyl-4-pyrones with DMF-DMA was developed. 2-(2-(Dimethylamino)vinyl)-4-pyrones are highly reactive substrates that undergo 1,6-conjugate addition/elimination or 1,3-dipolar cycloaddition/elimination followed by substitution of the dimethylamino group without ring opening. This strategy includes selective transformations leading to conjugated and isoxazolyl-substituted 4-pyrone structures. The photophysical properties of the prepared 4-pyrones were determined in view of further design of novel merocyanine fluorophores. A solvatochromism was found for enamino-substituted 4-pyrones accompanied by a strong increase in fluorescence intensity in alcohols. The prepared conjugated structures demonstrated valuable photophysical properties, such as a large Stokes shift (up to 204 nm) and a good quantum yield (up to 28%).