Frustrated Lewis Pair Chelation as a Vehicle for Low‐Temperature Semiconductor Element and Polymer Deposition

The stabilization of silicon(II) and germanium(II) dihydrides by an intramolecular Frustrated Lewis Pair (FLP) ligand, PB , ⁱPr₂P(C₆H₄)BCy₂ (Cy=cyclohexyl) is reported. The resulting hydride complexes [PB{SiH₂}] and [PB{GeH₂}] are indefinitely stable at room temperature, yet can deposit films of silicon and germanium, respectively, upon mild thermolysis in solution. Hallmarks of this work include: 1) the ability to recycle the FLP phosphine‐borane ligand ( PB ) after element deposition, and 2) the single‐source precursor [PB{SiH₂}] deposits Si films at a record low temperature from solution (110 °C). The dialkylsilicon(II) adduct [PB{SiMe₂}] was also prepared, and shown to release poly(dimethylsilane) [SiMe₂]_n upon heating. Overall, this study introduces a “closed loop” deposition strategy for semiconductors that steers materials science away from the use of harsh reagents or high temperatures.     

Indium-mediated tandem radical addition-cyclization-trap reactions in aqueous media

[reaction: see text] Tandem carbon-carbon bond-forming reactions were studied by using indium as a single-electron-transfer radical initiator. The radical addition-cyclization-trap reaction of a substrate having a vinyl sulfonamide group and an olefin moiety proceeded smoothly in aqueous media. The radical addition-cyclization reaction of hydrazone gave the functionalized cyclic products.     

Synthesis of nitrogen-bridged terthiophenes by tandem Buchwald-Hartwig coupling and their properties

The first synthesis of nitrogen-bridged terthiophenes (NBTTs) has been achieved by a tandem Buchwald-Hartwig coupling of 3,3',3",4'-tetrabromo-2,2':5',2"-terthiophene. Several NBTT derivatives bearing aryl or alkyl moieties on the N-atoms could be synthesized. Their fundamental electrochemical characteristics and HOMO-LUMO levels were found to be influenced by the substituents on the N-atoms.     

Development of new synthetic reactions for nitrogen-containing compounds and their application

Nitrogen-containing compounds are core parts not only of natural and synthetic medicines but also of biologically active compounds including natural products. This review focuses on the development of new synthetic reactions for nitrogen-containing compounds via three methodologies: the reductive photocycloaddition reaction of enamides, radical addition reaction, and nucleophilic addition reaction. Newly developed reactions were successfully applied to the synthesis of various types of nitrogen-containing compounds including medicines, lead compounds to new drugs, natural alkaloids, and others.     

Temperature-responsive hydrogels from cellulose

The aim of this work is to prepare the temperature-responsive cellulosic hydrogels undergoing a large volume change in an aqueous solution on heating or cooling. To this end, we prepared 0-methyl cellulose (MC) and O-(Z-hydroxy-3-butoxypropyl) cellulose (HBPC) which precipitate out of solution on heating without forming gel. MC and HBPC derivatives prepared by homogeneous reactions were proved to be promising raw materials for the cellulosic hydrogels mentioned above. The results on the phase separation of the derivatives were discussed in terms of the distribution of substituents along the cellulose chain and in the anhydroglucose units.