C(sp2)-H selenylation of substituted benzo[4,5]imidazo[2,1-b]thiazoles using phenyliodine(iii)bis(trifluoroacetate) as a mediator.

Herein, an expeditious metal-free regioselective C-H selenylation of substituted benzo[4,5]imidazo[2,1-b]thiazole derivatives was devised to synthesize structurally orchestrated selenoethers with good to excellent yields. This PIFA [bis(trifluoroacetoxy)iodobenzene]-mediated protocol operates under mild conditions and offers broad functional group tolerance. In-depth mechanistic investigation supports the involvement of radical pathways. Furthermore, the synthetic utility of this methodology is portrayed through gram-scale synthesis.

Metal free C-3 chalcogenation (sulfenylation and selenylation) of 4H-pyrido[1,2-a]pyrimidin-4-ones.

An expeditious metal free C-3 chalcogenation of 4H-pyrido[1,2-a]pyrimidin-4-one has been devised to synthesize diversely orchestrated 3-ArS/ArSe derivatives in high yields (up to 95%). This operationally simple reaction proceeds under mild reaction conditions, can be executed in gram scale, and also highlights broad functional group tolerance. Preliminary experimental investigation suggests a radical mechanistic pathway for these transformations.

Generation of ArS- and ArSe-Substituted 4-Quinolone Derivatives Using Sodium Iodide As an Inducer.

An operationally simple sodium iodide-mediated C-S and C-Se bond formation protocol involving substituted 4-quinolone and thiols/diselenide to generate different ArS/ArSe-substituted 4-quinolone derivatives in excellent yields was developed. The versatility of this methodology has been successfully demonstrated by extension of the suitable reaction conditions to both substrates having different substituents. This regioselective C-H bond activation approach provides a direct access of structurally diverse 3-sulfenylated/selenylated 4-quinolone derivatives. Moreover, this new method proceeds without a transition-metal catalyst and prerequisite NH protection of 4-quinolone derivatives.