Abstract:Novel electron-deficient chiral hypervalent iodine reagents were prepared in good overall yields. The reactivity and stereoselectivity of these reagents in oxidative rearrangements of alkenes to α-aryl ketones was investigated. The results show that the new reagents have good reactivity and generate products with high enantiomeric excess.The chemistry of hypervalent iodine reagents has witnessed a massive growth and development in the 21 st century. The extensive interest in hypervalent iodine reagents is attributed to their powerful oxidizing properties, along with their easy handling, commercial availability and benign environmental impact. Their synthetic applications include oxidation, halogenation, amination, C-C bond formation, heterocyclization and rearrangement reactions. 1,2,3Recently, many efforts were devoted to the development of hypervalent iodine catalyzed chemical transformations. 4 The catalytic cycle relies on the re-oxidation of an iodine(I) species, mainly iodoarenes, into the corresponding hypervalent iodine compounds in the presence of a stoichiometric oxidant. Hydrogen peroxide, oxone, m-chloroperbenzoic acid, sodium perborate, and Selectfluor ® are commonly used terminal oxidants in such catalytic transformations. The utilization of chiral iodoarenes as organocatalysts for different enantioselective transformations is a fastgrowing research area and several approaches have been published recently. 5Chiral hypervalent iodine(III) reagents have been very successfully used in stereoselective synthesis and received much attention. 6 Fujita 7 and Ishihara 8 initially published the synthesis and use of chiral hypervalent iodine reagents based on lactic acid. Many reactions have been investigated using these chiral reagents and in some of them very high stereoselectivities have been obtained. We also have contributed to that development and published highly stereoselective oxyaminations 9 and also the first stereoselective rearrangements based on chiral, lactic acid-based iodine(III) reagents. 10 The investigation of more recent rearrangements employing additional orthoesters to generate α-aryl esters as reaction products proved to be less efficient with the known lactic acid-based iodine(III) reagents. We therefore decided to prepare more reactive versions of the reagents 1 by the attachment of an electron-withdrawing group such as a trifluoromethyl substituent (R = CF 3 ) in the para-position to the iodine (Figure 1). This should enhance the electrophilicity of the hypervalent Ph Ph

A simple synthesis of a library of novel C−N axially chiral iodoarenes is achieved in a three‐step synthesis from commercially available aniline derivatives. C−N axial chiral iodine reagents are rarely investigated in the hypervalent iodine arena. The potential of the novel chiral iodoarenes as organocatalysts for stereoselective oxidative transformations is assessed using the well explored, but challenging stereoselective α‐oxytosylation of ketones. All investigated reagents catalyse the stereoselective oxidation of propiophenone to the corresponding chiral α‐oxytosylated products with good stereochemical control. Using the optimised reaction conditions a wide range of products was obtained in generally good to excellent yields and with good enantioselectivities.

New heteroatom-containing pseudocyclic iodanes are being introduces as alternatives to the Koser reagent.

Environmentally friendly purely organic dye-sensitizedbased solar cells and photoelectrochemical cells have emerged as primary photovoltaic technologies due to their stabilities, cost effectivenesses, and equally high efficiencies compared to conventional ruthenium-based dyes. Nevertheless, back electron hole recombination, fast electron injection, wide band light harvesting, and environmental hazards are crucial aspects that govern advancement in photovoltaic technology. Organic photosensitizers having a delocalized π system of electrons end capped with electron acceptors (A) and donors (D) have easy synthesis methods, excellent abilities to confine solar energy, and exceptional tunable absorbances and have the potential to overcome the above-mentioned crucial aspects in combination with semiconductor−metal (plasmonic) nanohybrids. Here, we have reported enhanced photovoltaic activity of organic D-π-A type photosensitizer (RK1)-based plasmonic Au nanoparticle-decorated hybrid mesoporous TiO 2 photoanodes in dye-sensitized solar cells (DSSCs) and in dye-sensitized photoelectrochemical water splitting (DSPEC). The presence of plasmonic material not only reduces the back electron hole recombination but also the spectral overlap of its localized surface plasmon resonance (LSPR) band with that of organic sensitizer RK1 in close proximity to the TiO 2 surface, leading to the possibility of Forster resonance energy transfer (FRET) which further enhances the device performance. Further, an ultrafast spectroscopic study has been performed to study the excited-state charge and energy transfer dynamics of the interfaces of the nanohybrids. Our analysis demonstrates the identification of a specific unique combination of the nanohybrid which is useful to design a new generation of solar light-harvesting materials, especially in the case of DSPECs.