The synthesis of a crystalline ethynyl-1,2-benziodoxol-3(1H)-one (EBX)−acetonitrile complex is described. EBX has been widely used as an active species for a variety of reactions; however, its high instability has so far prevented its isolation. The EBX−acetonitrile is self-assembled into a double-layered honeycomb structure through weak hypervalent iodine secondary interactions and hydrogen bonding. The N-ethynylation of a variety of sulfonamides using the EBX− acetonitrile complex as a substrate under mild conditions is also described.

Imidazo[1,5-a]pyridin-1-ylalkyl alcohols were reacted with diphenylborinic acid to give boron complexes in which nitrogen and oxygen atoms were coordinated to a boron atom. The use of imidazo[1,5-a]pyridin-1-ylalkyl alcohol with two 2-pyridyl groups also gave a boron complex, but the nitrogen atom in a 2-pyridyl group, rather than that in an imidazopyridyl group, was coordinated to the boron atom. The molecular structures of these complexes were revealed by X-ray analyses. The fluorescence spectra of the complexes were generally observed at wavelengths shorter than those for the starting materials and well-known boron complexes of 8-hydroxyquinolines.

A series of 5-N-arylaminothiazoles was prepared by reacting thioamide dianions derived from secondary thioamides with thioformamides, followed by sequential oxidation with iodine. X-ray analyses demonstrated that they adopt structures that are highly twisted from planar conformations. Their orientations were tuned by the steric and/or electronic interactions of the substituents at their 2-, 4-, and 5-positions. The 5-aminothiazoles exhibited a range of fluorescent emissions, from blue to orange. Although the absorption spectra were independent of the polarity of the solvent, fluorescent emissions were influenced by the polarity of the solvent: in more polar solvents, the emissions were red-shifted. These phenomena were examined in terms of Lippert-Mataga plots and the change in the dipole moment between the ground and excited states. They also exhibited emissions in the solid state, again from blue to orange. Cyclic voltammetry of the 5-aminothiazoles showed reversible waves of one-electron oxidation. The half-potential of the oxidation was reduced by the introduction of electron-donating groups to the phenyl groups on the nitrogen atom at the 5-position. DFT calculations were carried out to determine the energy levels of the HOMO and LUMO. Finally, the results of TG-DTA showed that they are thermally stable.

The reactions of phosphonates having a binaphthyloxy group with Grignard reagents gave the corresponding Pstereogenic phosphinates in good to high yields with high diastereoselectivity. In this reaction, an axis-to-center chirality transfer from a binaphthyl group to the resulting phosphorus atom took place stereospecifically. Both diastereomers with opposite configurations could be obtained by changing the combination of carbon-containing functional groups on the phosphorus atom and the Grignard reagents. Keywords: P-Stereogenic phosphonates | Binaphthyloxy phosphinate | Grignard reagentsIncreasing attention has been paid to the development of synthetic methods for P-stereogenic organophosphorus compounds with PC bonds 1 because of their wide applicability as optically active ligands and organocatalysts. For example, catalytic asymmetric desymmetrization of P-achiral substrates leads to P-stereogenic products.2 The addition of stoichiometric amounts of optically active compounds to P-achiral substrates can form diastereomers, and subsequent separation gives one of the diastereomers of P-stereogenic products.3 P-Chiral racemic substrates are also used to generate P-stereogenic products by procedures involving the separation of diastereomers 4 or catalytic selective functionalization of one of the enantiomers. 5 Additionally, the functionalization of optically active P-chiral substrates and of P-achiral substrates with a chiral auxiliary is being extensively developed. 6 In this context, we recently reported the transfer of the axial chirality of the binaphthyl group in phosphorothioic acid esters to the central P-chirality of monofluorinated thiophosphates via a reaction with a fluoride anion (Scheme 1a). 7In a series of studies on chalcogen isologues of phosphoric acid derivatives with a binaphthyl group, we synthesized a wide variety of phosphonates with a binaphthyl group. 8 We then envisioned that a conceptually new strategy for obtaining Pstereogenic organophosphorus compounds, i.e., axis-to-center chirality transfer, might play a role in the reaction of these phosphonates with a range of carbon nucleophiles (Scheme 1b). In fact, Drabowicz and co-workers used thienyllithium in the reaction of Scheme 1b, but the corresponding product was formed after 7 days in moderate yield with a diastereoselectivity of 63:37.9 Herein, we report a highly diastereoselective synthesis of P-stereogenic phosphinates by the reaction of phosphonates having a binaphthyloxy group with Grignard reagents.Initially, P-methylphosphonate 1a reacted with ethyl Grignard reagent 2b (1 equiv) in THF at 0°C for 30 min to give P-stereogenic phosphinate 3ab as a single diastereoisomer in 88% yield (Scheme 2a). In contrast to the reaction in Scheme 1a, only one of the PO bonds in 1a cleaved, and one molecule of Grignard reagent was introduced to the phosphorus atom. To our delight, the use of P-ethylated ester 1b and methyl Grignard reagent 2a led to phosphinate 3ba, which has a configuration opposite that of 3ab, in high yield (Scheme 2b...

Reactions of thioamide dianions, derived from secondary N-arylmethyl thioamides using BuLi, with thioformamides followed by the addition of iodine to yield 5-amino-2-thiazolines are described. Treatment of the 5-amino-2-thiazolines with iodine leads to a highly efficient production of 5-aminothiazoles. When N,N-diarylthioformamides are employed in this process, fluorescent 5-N,N-diarylthiazoles are obtained.