Direct Arylation of Simple Arenes with Aryl Bromides by Synergistic Silver and Palladium Catalysis.

The direct, catalytic arylation of simple arenes in small excess with aryl bromides is disclosed. The developed method does not require the assistance of directing groups and relies on a synergistic catalytic cycle in which phosphine-ligated silver complexes cleave the aryl C-H bond, while palladium catalysts enable the formation of the biaryl products. Mechanistic experiments, including kinetic isotope effects, competition experiments, and hydrogen-deuterium exchange, support a catalytic cycle in which cleavage of the C-H bond by silver is the rate-determining step.

gem-Difluoroallylation of Aryl Halides and Pseudo Halides with Difluoroallylboron Reagents in High Regioselectivity.

We report the palladium-catalyzed gem-difluoroallylation of aryl halides and pseudo halides with 3,3-difluoroallyl boronates in high yield with high regioselectivity, and we report the preparation of the 3,3-difluoroallyl boronate reactants by a copper-catalyzed defluorinative borylation of inexpensive gaseous 3,3,3-trifluoropropene with bis(pinacolato)diboron. The gem-difluoroallylation of aryl and heteroaryl bromides proceeds with low catalyst loading (0.1 mol % [Pd]) and tolerates a wide range of functional groups, including primary alcohols, secondary amines, ethers, ketones, esters, amides, aldehydes, nitriles, halides, and nitro groups.

The Effect of Freeze-Drying Pretreatment on the Accuracy of Near Infrared Spectroscopic Food Analysis to Predict the Nutritive Values of Japanese Cooked Foods.

The official testing methods for establishing nutritive values are accurate but relatively costly and time-consuming. Near infrared spectroscopy (NIRS) is potentially an alternative method that can analyze several components in a few minutes using an exclusively electronic instrument with no need for a laboratory expert. However, the accuracy of commercial NIRS spectroscopic food analyzers is not sufficient for Japanese food labeling, because of interference from moisture contained in the foods.

Observation of Microstructure Formation During Freeze-Drying of Dextrin Solution by X-ray Computed Tomography.

X-ray computed tomography (CT) was used to observe microstructure formations during freeze-drying of a dextrin solution. A specially designed freeze-drying stage was equipped at the X-ray CT stage. Frozen and dried microstructures were successfully observed.

Total Synthesis of (+)-Cytosporolide A via a Biomimetic Hetero-Diels-Alder Reaction.

The first total synthesis of (+)-cytosporolide A was achieved by a biomimetic hetero-Diels-Alder reaction of (-)-fuscoatrol A with o-quinone methide generated from (+)-CJ-12,373. The dienophile, highly oxygenated caryophyllene sesquiterpenoid (-)-fuscoatrol A, was synthesized from the synthetic intermediate in our previous total synthesis of (+)-pestalotiopsin A. The o-quinone methide precursor, isochroman carboxylic acid (+)-CJ-12,373, was synthesized through a Kolbe-Schmitt reaction and an oxa-Pictet-Spengler reaction.

Asymmetric construction of all-carbon quaternary stereocenters by chiral-auxiliary-mediated Claisen rearrangement and total synthesis of (+)-bakuchiol.

An asymmetric Claisen rearrangement using Oppolzer’s camphorsultam was developed. Under thermal conditions, a geraniol-derived substrate underwent the rearrangement with good stereoselectivity. The absolute configuration of the newly formed all-carbon quaternary stereocenter was confirmed by the total synthesis of (+)-bakuchiol from the rearrangement product.