The Michael Additiaons Of Enaminones: Sythesis Of Pyridones And Thiapyrones

Enaminones have emerged as versatile synthetic intermediates. Their chemistry has been the focus of intense research for decades, particularly in heterocyclic synthesis, and continues to be an active area of research today. Many valuble azo-compounds can be prepared from enaminones, for example, pyrrole, oxazoles, pyridinones and quinolines. In addition, some of these compounds are pharmaceuticals possessing anticonvulsant and analeptic activity, combined with low toxicity.Pyridones has become very important heterocyclics. Some of them are the intermediates in medicinal chemistry. Particularly, N-substituted pyridone compounds have verastile physiological activity. For instance, they can sterilize, ease pain, resist tumour and cure parkinsonism. As the development of fuction material, pyridones have important uses in dyestuff, ink-jet printing, thermochromic materials photosensitive materials and pesticide.In the last decades, thiapyrone derivatives including types of thiin-4-ones and 2,3-dihydrothiopyran-4-ones have gained increasing attention for both the interest of such heterocycles themselves and their importance as key units in medicinal chemistry and versatile intermediates in organic sythesis.In the present work, we have successfully developed divergent synthetic methodology for pyridoneas and thiopyrones from enaminones based on their special structural properties. The main achievements are described in the following two aspects:1. A facile and efficient synthesis of enaminones has been developed. Subjected to N, N-dimethylformamide dimethyl acetal (DMFDMA) in DMF, a series ofα-acyl,α-carbamoyl ketene-S, S-acetals were converted into the corresponding enaminones in high yields. We successfuly prepared a series of pyridones.2. A convenient and efficient synthesis of highly substituted thiopyrones-4-ones is developed via the Michael addition.of readily available enaminones. This protocol is associated with readily available starting materials, mild conditions and good yields.In summary, a facile and convenient synthesis of heterocyclic compounds is developed through enaminones, mild conditions and high yields. Moreover, these results also extend [5C+1X] annulation strategy proposed in our previous research work.