Design and synthesis of coumarinyl 1,4-benzodioxanes as potential anti-oxidant

Access to π-Extended Heterocycles Containing Pyrrolo-Coumarin Cores Involving -COCH3 as a Traceless Directing Group and Materializing Two Successive sp2C-H/sp3N-H and sp2C-H/sp2N-H Activations

An efficient protocol has been developed for the preparation of π-extended N-heterocycles involving a Rh(III)-catalyzed C-H activation reaction starting from 3-acetamidocoumarins and internal alkynes. The isolation of the intermediate pyrrolo-coumarin suggests that the -COCH₃ group in acetamidocoumarins performs the role of a traceless directing group. Besides, the use of commercially available [Cp*RhCl₂]₂ adds more importance as no additional modification of the catalyst is required. A two-step protocol bearing intermediate pyrrolo-coumarin can be further functionalized to highly decorated heterocyclic moieties materializing sp² C-H and sp² N-H coupling. Moreover, one of the pyrrolo-coumarin compounds (3da) is capable of differentiating between Cr(III) and Cr(VI) ions as revealed via fluorescence spectroscopy. In addition, intermediate pyrrolo-coumarin is further functionalized to spirocyclic N-heterocycles.

One-flask synthesis of pyrazolone thioethers involving catalyzed and uncatalyzed thioetherification pathways of pyrazolones

One-pot thioetherification of pyrazolones through cross-coupling as well as an aromatic S_N2 pathway using elemental sulfur as the sulfur source.