The Proton Cryptate of Hexaethylenetetramine

The next higher homologue of hexamethylenetetramine was synthesized as the proton cryptate H⁺@ 1 ⋅Br⁻ (shown schematically), and its X-ray structure determined. The proton trapped by the lone pairs accumulated at the center of the T-symmetric tetraaza cage could not be exchanged or removed, even after heating for three days in 3 M NaOD.     

Extremely Facile and Selective Nickel-Catalyzed Allyl Ether Cleavage

Child's play! Allyl ethers as protecting groups for hydroxyl functions can be removed readily with a combination of DIBAL and catalytic amounts of [NiCl₂(dppp)]. Propene is expelled in this remarkably selective reaction, and a nickel-catalyzed hydroalumination–elimination pathway is proposed [Eq. (a)]. dppp=propane-1,3-diylbis(diphenylphosphane).     

Effects of Dye‐Adsorption Solvent on the Performances of the Dye‐Sensitized Solar Cells Based on Black Dye

The effects of the dye‐adsorption solvent on the performances of the dye‐sensitized solar cells (DSSCs) based on black dye have been investigated. The highest conversion efficiency (10.6 %) was obtained in the cases for which 1‐PrOH and the mixed solvent of EtOH and tBuOH (3:1 v/v) were employed as dye‐adsorption solvents. The optimized value for the dielectric constant of the dye‐adsorption solvent was found to be around 20. The DSSCs that used MeOH as a dye‐adsorption solvent showed inferior solar‐cell performance relative to the DSSCs that used EtOH, 1‐PrOH, 2‐PrOH, and 1‐BuOH. Photo‐ and electrochemical measurements of black dye both in solution and adsorbed onto the TiO₂ surface revealed that black dye aggregates at the TiO₂ surface during the adsorption process in the case for MeOH. Both the shorter electron lifetime in the TiO₂ photoelectrode and the greater resistance in the TiO₂–dye–elecrolyte interface, attributed to the dye aggregation at the TiO₂ surface, cause the decrease in the solar‐cell performance of the DSSC that used MeOH as a dye adsorption solvent.     

PDMS-glass hybrid microreactor array with embedded temperature control device. Application to cell-free protein synthesis

A microreactor array was developed which enables high-throughput cell-free protein synthesis. The microreactor array is composed of a temperature control chip and a reaction chamber chip. The temperature control chip is a glass-made chip on which temperature control devices, heaters and temperature sensors, are fabricated with an ITO (indium tin oxide) resistive material. The reaction chamber chip is fabricated by micromolding of PDMS (polydimethylsiloxane), and is designed to have an array of reaction chambers and flow channels for liquid introduction. The microreactor array is assembled by placing the reaction chamber chip on the temperature control chip. The small thermal mass of the reaction chamber resulted in a short thermal time constant of 170 ms for heating and 3 s for cooling. The performance of the microreactor array was examined through the experiments of cell-free protein synthesis. By measuring the fluorescence emission from the products, it was confirmed that GFP (Green Fluorescent Protein) and BFP (Blue Fluorescent Protein) were successfully synthesized using Escherichia coli extract.     

Synthesis of nitrogen-containing compounds using chromium Fischer carbene complexes

Synthetic utility of the Fischer-type carbene complexes of chromium for the preparation of nitrogen-containing compounds is demonstrated. Alkoxy carbene complexes reacted with imines to give (optically active) 3-pyrrolines and beta-methoxy allylic amine derivatives in good yields. The amino carbene complexes reacted with alpha,beta-unsaturated aldehydes to give substituted pyrroles in good yields.     

Remarkable Differences in Reactivity between Benzothiazoline and Hantzsch Ester as a Hydrogen Donor in Chiral Phosphoric Acid Catalyzed Asymmetric Reductive Amination of Ketones

Described herein are differences in behavior between a Hantzsch ester and a benzothiazoline as hydrogen donors in the chiral phosphoric acid catalyzed asymmetric reductive amination of ketones with p‐anisidine. The asymmetric reductive amination of ketones with a Hantzsch ester as a hydrogen donor provided the corresponding chiral amines exclusively, regardless of the structures of the ketones, whereas a similar transformation with a benzothiazoline provided chiral amines and p‐methoxyphenyl‐protected primary amines in variable yields, depending on the structures of both the ketones and benzothiazolines. Because a benzothiazoline has an N,S‐acetal moiety that is vulnerable to p‐anisidine, the primary amine can be formed through transimination of the benzothiazoline with p‐anisidine followed by reduction of the resulting aldimine with remaining benzothiazoline.