Facile synthesis of glycerol carbonate from glycerol using selenium‐catalyzed carbonylation with carbon monoxide

The commercial production of glycerol has increased considerably for several years, because of its rising inevitable formation as a by‐product of biodiesel. For the effective utilization of glycerol, a new synthesis of glycerol carbonate (4‐hydroxymethyl‐2‐oxo‐1,3‐dioxolane) that is used as solvents and raw material of plastics from glycerol was explored. By combined the selenium‐catalyzed carbonylation of slightly excess of glycerol with carbon monoxide and potassium carbonate under 0.1 MPa at 20°C for 4 h in DMF with the oxidation of resulting selenocarbonate salt with molecular oxygen (0.1 MPa, 20 °C) for 2 h, glycerol carbonate was obtained in good yields (83–84%). However, sodium hydride to form sodium alkoxide in situ lowered the yield of glycerol carbonate. Use of triethylamine, 1‐methylpyrrolidine, and DBU as bases gave poor results. Furthermore, styrene carbonate was obtained in excellent yield (90%) under similar reaction conditions. The catalytic synthesis of glycerol carbonate was also brought about in the mixed gas atmosphere (carbon monoxide:oxygen = 3:1, 0.1 MPa, 20°C). Glycerol carbonate and styrene carbonate were obtained in reasonable yields (197% and 119%, based on selenium used). © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:541–545, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20640     

Stereochemical diversity in asymmetric cyclization via memory of chirality

An enantiodivergent asymmetric cyclization of N-Boc-N-omega-bromoalkyl-alpha-amino acid derivatives has been developed. With potassium amide bases in DMF, cyclization proceeds with retention of configuration, while inversion of configuration was observed with lithium amide bases in THF. Chirality of the parent amino acids was preserved during enolate formation and cyclization to give aza-cyclic amino acids in up to 98% ee with retention of configuration or inversion of configuration, depending on the reaction conditions. Thus, both enantiomers of cyclic amino acids with a tetrasubstituted stereocenter were prepared in high enantiomeric purity from readily available l-alpha-amino acids. This protocol is also applicable to a spirocyclization and an intramolecular conjugate addition of alpha-amino acid derivatives, giving either of the enantiomers of a diazaspiro compound and a tetrahydroisoquinoline derivative, respectively, in up to 99% ee.     

system with chiral SU(3) effective interaction

The K⁻pp system is investigated using a variational approach with realistic two-body interactions: the Argonne v18 NN potential and an energy dependent effective interaction derived from chiral SU(3) coupled-channel dynamics. Uncertainties in subthreshold extrapolations of the interaction are considered. A weakly bound K⁻pp state is found, with a binding energy B=(19±3) MeV substantially smaller than suggested in previous calculations. The decay width Γ(K⁻pp→πΣN) is estimated to range between about 40 and 70 MeV.     

Synthesis and Self-Aggregation of Chlorophyll-a Derivatives Possessing a Hydroxymethyl Group in the C20-Substituent with Ethynylene and/or Phenylene Linkers

Chlorophyll(Chl)-a derivatives containing some rigid linkers in the C20 substituents, which were inserted between a hydroxymethyl group and the chlorin π-skeleton, were synthesized and their self-aggregation abilities were investigated. Measurements of electronic absorption, circular dichroism and infrared absorption spectra revealed that the zinc complex of a Chl-a derivative bearing a (p-ethynyl)benzyl alcoholic moiety at the C20-position gave its J-aggregates in an aqueous micellar solution through the hydrogen and coordination bonding. These results exhibited the potential of Chl-a derivatives bearing a hydroxyl group in the C20 substituents as the model compounds for chlorosomal light-harvesting antennas.     

An arrayed-window microfluidic device for observation of mixed nanoparticles with an X-ray free-electron laser

Optical Review - A microfluidic device was developed for coherent diffraction imaging using an X-ray free-electron laser (XFEL-CDI). Liquid samples, which are separately packed in reservoirs of the...     

Flow Friedel–Crafts alkylation of 1-adamantanol with arenes using HO-SAS as an immobilized acid catalyst

In this communication flow Friedel–Crafts alkylation was studied using hydroxy-substituted sulfonic acid-functionalized silica as a catalyst and 1-adamantanol as a model substrate. The reaction of 1-adamantanol ( 1a ) with toluene ( 2a ) proceeded well with 5 min of residence time at 120°C to give good yield of 1-tolyladamantane ( 3a ) as a 1:9 mixture of meta and para isomers. When the flow synthesis was carried out over 2.5 hr of running time, the collected five fractions contain the product 3a in 97–92% yields, suggesting the durability of the catalyst.     

Anthracene derivatives and the corresponding dimers with TEMPO radicals

Anthracene derivatives with several TEMPO radicals (2-4, 10) were prepared, and each photodimerization reaction was investigated. Although the photodimerization was unsuccessful in obtaining the dimers of anthracenes 2 and 3, which could be alternatively prepared in a stepwise manner, the photodimers of anthracenes 4 and 10 were available by the direct photoreaction. The dissociation reaction of the dimers proceeded well by heating them in solution to give the corresponding monomers in each case, and thus the reversible system could be constructed in the latter two systems. While no large difference was observed in their magnetic behaviors between the monomer/dimer pair of 4 and 8, an intriguing difference was found in the magnetic behaviors for the pair of 10 and 11 from ferromagnetic interactions in 10 to the variable magnetic interactions in 11 depending on the solvent molecules incorporated in the crystals.