Multicomponent Synthesis of Annelated Thiopyranones by Coupling-Addition-Nucleophilic Aromatic Substitution Sequence

Multicomponent Synthesis of Annelated Thiopyranones by Coupling-Addition-Nucleophilic Aromatic Substitution Sequence 

Thiopyranone is the thio homologue of pyranone, a core constituent of many namral products. In their own right, thiochromenones, benzo annelated thiopyranones that are related to the class of flavones, are as well potent drug candidates and 

In general, 4//-thiochromen-4-ones are synthesized either by condensation of p-keto esters and thiophenols with pol3q)hosphoric acid [213-215] or by cyclization of p-substituted cinnamates derived from thiophenols and appropriate propiolates [211, 216, 217]. 

Furthermore, as a consequence of pronounced zwitterionic character of the computed electronic ground state, intense bathochromic halochromicity of the longest wavelength absorption bands with concomitant weak orange fluorescence can be observed upon protonation [221]. 

7 Multicomponent Synthesis of Heterocycles by Coupling-Isomerization-Cyclocondensation Sequences 

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