I2/DMSO-Promoted Synthesis of Diaryl Sulfide- and Selenide-Embedded Arylhydrazones.

Functionalization and derivatization of arylhydrazones are important in pharmaceutical, medicinal, material, and coordination chemistry. In this regard, a facile I2/DMSO-promoted cross-dehydrogenative coupling (CDC) for direct sulfenylation and selenylation of arylhydrazones has been accomplished utilizing arylthiols/arylselenols at 80 °C. This method provides a metal-free benign route for the synthesis of a variety of arylhydrazones embedded with diverse diaryl sulfide and selenide moieties in good to excellent yield. In this reaction, molecular I2 acts as a catalyst, and DMSO is utilized as a mild oxidant as well as solvent to produce several sulfenyl and selenyl arylhydrazones through a CDC-mediated catalytic cycle.

Synthesis of Hydroxylated Polycyclic Pyrrolo/Indolo[1,2-a]quinoxaline-Fused Lactam Derivatives via PhI(OAc)2-Promoted 1,2-Bond Migration and Solvent Insertion.

PhI(OAc)2-mediated ring expansion via 1,2-bond migration and concurrent solvent insertion generate hydroxylated polycyclic pyrrolo/indolo[1,2-a]quinoxaline-fused lactam derivatives in a highly diastereoselective fashion from spiro-fused quinoxalines in good-to-excellent yield. X-ray crystal structure analysis reveals that the polycyclic lactams are nonplanar molecules devoid of any symmetry as they possess one or two axially chiral biaryl or N-arylindolyl bridges along with one chiral center at the bridgehead carbon.

Three-Component Synthesis of Pyrrolo/indolo[1,2-a]quinoxalines Substituted with o-Biphenylester/N-arylcarbamate/N-arylurea: A Domino Approach Involving Spirocyclic Ring Opening.

A p-TsOH-mediated one-pot, three-component methodology has been developed for the synthesis of pyrrolo/indolo[1,2-a]quinoxalines substituted with o-biphenylester/N-arylcarbamate/N-arylurea at the C-4 position under open-air heating conditions. The protocol offers a transition-metal-free and external oxidant-free solvent-mediated pathway to afford a library of diversely substituted quinoxalines in moderate to good yields. Various water-miscible aliphatic alcohols and amines participate in the reactions both as solvent as well as reactant. X-ray crystal structure analysis suggests that some of the suitably substituted quinoxalines may exhibit atropisomerism at room temperature.

A novel tryptamine-appended rhodamine-based chemosensor for selective detection of Hg2+ present in aqueous medium and its biological applications.

A novel rhodamine-tryptamine conjugate-based fluorescent and chromogenic chemosensor (RTS) for detection of Hg2+ present in water was reported. After gradual addition of Hg2+ in aqueous methanol solution of RTS, a strong orange fluorescence and deep-pink coloration were observed. The probe showed high selectivity towards Hg2+ compared to other competitive metal ions. The 1:1 binding stoichiometry between RTS and Hg2+ was established by Job's plot analysis and mass spectroscopy. Initial studies showed that the synthesized probe RTS possessed fair non-toxicity and effectively passed through cell walls of model cell systems, viz., human neuroblastoma (SHSY5Y) cells and cervical cells (HeLa) to detect intercellular Hg2+ ions, signifying its utility in biological system. The limit of detection (LOD) was found to be 2.1 nM or 0.42 ppb by fluorescence titration. Additionally, the potential relevance of synthesized chemosensor for detecting Hg2+ ions in environmental water samples has been demonstrated. Graphical abstract ᅟ.