2H-Pyran-2-ones and their annelated analogs as multifaceted building blocks for the fabrication of diverse heterocycles
2017
Pratap, Ramendra | Ram, Vishnu Ji
2H-Pyran-2-ones are widely present in nature and found as either isolated or in fused form. Depending on the fusion of benzene ring, pyran can give coumarins, isocoumarins, dibenzopyrans etc. This class of molecules exhibit excellent biological activity and photophysical properties. Apart from these, 2H-pyran-2-one also acts as very good Michael acceptor, therefore act as very important synthetic precursor. Suitably functionalized 2H-pyran-2-one has been widely explored for their synthetic potential. In this review, we have focused on use of different nucleophiles based on carbon, nitrogen, oxygen and sulfur to generate vast molecular diversity. The functionalized 2H-pyran-2-ones exhibit three electrophilic centres with different electrophilicity. Use of suitable nucleophiles can act on either of the position based on its reactivity to generate new chemical entity. 2H-Pyran-2-one has been explored as precursor for the synthesis of various biologically important nucleuses like pyridine, pyrimidine, quinolines, isoquinolines, fused quinolines, pyrazole, pyrroles, imidazopyridine, thiazole, oxazole, fused and isolated pyrans, coumarins, isocoumarins, benzothiophenes, dibenzohiophenes, dibenzofurans, diazapines, oxahelicines, thia-oxa helicines, and various other heterocycles under base mediated conditions. Use of suitably substituted 2H-pyran-2-one and nucleophile can generate new molecular entity. In this review, we have discussed the properties, synthesis and their synthetic applications to generate various classes of heterocycles.
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