Synthesis of <i>gem</i>-Difluoromethylene Building Blocks through Regioselective Allylation of <i>gem</i>-Difluorocyclopropanes

<i>gem</i>-Difluorocyclopropane derivatives react with allyltri­butyl­stan­nane in the presence of 2,2′-azo­bis­(iso­butyro­nitrile) to afford 1,6-dienes with a <i>gem</i>-difluoro­methylene moiety at the allylic position. The reaction proceeds regioselectively with high yields, and the 1,6-dinenes obtained are good precursors for cyclic systems containing a <i>gem</i>-difluoro­methylene moiety. Although <i>S</i>-methyl carbono­dithioate also works as a leaving group, rearrangement of the leaving group competes with the desired allylation, depending on the amount of allyltri­butyl­stan­nane

Synthesis of Ionic Liquids Equipped with 2‑Methoxy­ethoxy­methyl/Methoxy­methyl Groups Using a Simple Microreactor System

A simple microreactor system has been utilized for the continuous flow synthesis of novel ionic liquids having a (2-meth­oxy­ethoxy)­methyl or methoxy­methyl substituent. Conversion rates of <i>N</i>-bases and tributylphosphine in the microreactor system are faster than those in the batch system because of less diffusion distance in the tube reactor. This method allows us to prepare ionic liquids in efficient yields with high purity

CO₂ Solubility in Ether Functionalized Ionic Liquids on Mole Fraction and Molarity Scales

The effect of ether functional group(s) in the cation, anion, and both of the ions in ionic liquids on physical absorption of CO₂ are revisited in the present work. The solubilities of CO₂ in ether functionalized ammonium and pyrrolidinium salts, [N_211MEE]­[Tf₂N], [Pyr_1MOM]­[Tf₂N], and [Pyr_1MOM]­[FSA] were previously reported together with the corresponding alkyl analogues. In addition to such cation-modified ionic liquids, we investigate a new family of ether functionalized ionic liquids with alkoxy sulfates; [C₂mim]­[C₁(OC₂)₂SO₄], [P_444ME]­[C₆SO₄], [P_444ME]­[C₁OC₂SO₄], [P_444ME]­[C₁(OC₂)₂SO₄], and [N_221ME]­[C₁(OC₂)₂SO₄]. The CO₂ solubility data on the molarity as well as the mole fraction scales are presented in a series of ether functionalized ILs with a brief overview of the previously reported results. It has become apparent that the introduction of an ether functional group in anions more effectively improves the CO₂ solubilities on both the mole fraction and molarity scales than that in cations. The effects of the cation, anion, and dual functionalization with ether groups on the physical solubility of CO₂ are discussed with the volumetric properties in terms of the molecular structures of ILs

Ionic Liquid Engineering for Lipase-Mediated Optical Resolution of Secondary Alcohols: Design of Ionic Liquids Applicable to Ionic Liquid Coated-Lipase Catalyzed Reaction

A rational design of phosphonium ionic liquid for ionic liquid coated-lipase (IL1-PS)-catalyzed reaction has been investigated: very rapid transesterification of secondary alcohols was accomplished when IL1-PS was used as catalyst in tributyl­((2-methoxyethoxy)­methyl)­phosphonium bis­(trifluoromethanesulfonyl)­amide ([P_444MEM]­[NTf₂]) or <i>N-</i>ethyl-<i>N</i>-((2-methoxyethoxy)­methyl)-<i>N</i>-methylethanaminium bis­(trifluoromethanesulfonyl)­amide ([N_221MEM]­[NTf₂]) as solvent with excellent enantioselectivity. It was also revealed that ammonium ionic liquid influenced the lipase reactivity more strongly than phosphonium ionic liquids. Increased <i>K</i>_cat value was suggested to be the most important factor at work in IL1-PS in these ionic liquid solvents. The <i>K</i>_cat value of (<i>S</i>)-1-phenyethanol in [N_444MEM]­[NTf₂] was similar to that of <i>i</i>-Pr₂O, and 1.6-fold acceleration was achieved for (<i>R</i>)-1-phenylethanol. On the other hand, the <i>K</i>_m value for (<i>R</i>)-isomer in [N_444MEM]­[NTf₂] was slightly larger than the reaction in <i>i</i>-Pr₂O, while it was significantly reduced for (<i>S</i>)-isomer. These results suggest that solvent provides a certain impact on the reactivity of the enzyme protein of IL1-PS

Enhanced Activity of a Lipase by the Coating with a Quaternary Ammonium Alkyl-PEG Sulfate Ionic Liquid and Cooperative Activation with an Amino Acid

Three types of quaternary ammonium salts, tris­(diethylamino)­cyclopropenium cetyl-PEG10 sulfate (TAC1), <i>N</i>,<i>N</i>,<i>N</i>,<i>N</i>-tetraethylammonium cetyl-PEG10 sulfate (TEA), and <i>N</i>,<i>N</i>-diethylpiperidinium cetyl-PEG10 sulfate (PP₂₂), have been prepared and evaluated for their activation property of Burkholderia cepacia lipase using them as coating materials of the enzyme. Among the three tested IL-coated enzymes, the TAC1-coated lipase PS (TAC1-PS) was especially suitable for the transesterification of 1-(pyridin-2-yl)­ethanol, 1-(pyridin-3-yl)­ethanol, 1-(pyridin-4-yl)­ethanol, and 4-phenylbut-3-en-2-ol. Although the reaction rate of 1-phenylethanol of the TAC1-PS-catalyzed reaction was inferior to that of IL1-PS, the enzyme was coated with the equivalent amount of l-methionine with TAC1, the resulting enzyme (TAC1-l-Met-PS) exhibited a higher activity compared to that of IL1-PS, and this was mainly contributed to the increasing <i>K</i>_cat value. We further succeeded in demonstrating the recyclable use of TAC1-PS in the [N_221MEM]­[Tf₂N] solvent system

Enantioselective Allylic Amination of Trifluoromethyl Group Substituted Racemic and Unsymmetrical 1,3-Disubstituted Allylic Esters by Palladium Catalysts

The palladium-catalyzed regio- and enantioselective allylic amination of trifluoromethyl group substituted racemic and unsymmetrical 1,3-disubstituted allylic esters has been accomplished. The enantioselective formation of the α-type allylic amines was attained by the dynamic kinetic asymmetric transformation (DYKAT)

Development of n‑Type Semiconductor Based on Cyclopentene- or Cyclohexene-Fused [C₆₀]‑Fullerene Derivatives

Properties of cyclopentene- or cyclohexene-fused [C₆₀]-fullerene derivatives as the acceptor in photovoltaic cells have been investigated by use of poly­(3-hexylthiophene) (P3HT) as the model donor polymer. Several cyclopentene- or cyclohexene-fused [C₆₀]-fullerene derivatives show high power conversion efficiency (PCE). The highest PCE was obtained for 3′,6′-dihydro-4′-phenoxycarbonyl-6′-methylbenzo­[1,9]­[5,6]­(C₆₀-<i>I</i>_<i>h</i>)­fullerene (3.2%); this is superior to that of [C₆₀]-PCBM with the P3HT polymer under the same experimental conditions. PCE of the OPV devices with alkyl-substituted cyclohexene-fused [C₆₀]-fullerenes depended on the alkyl substituent on the cyclohexene ring; compounds with substituents of odd-number alkyl groups showed better PCE than those compounds possessing even-number alkyl groups

Ruthenium-Catalyzed Regio- and Enantioselective Allylic Amination of Racemic 1‑Arylallyl Esters

The regio- and enantioselective allylic amination of racemic monosubstituted allylic esters, such as 1-arylallyl acetates, with cyclic secondary amines has been accomplished. The RuCl₃/(<i>S,S</i>)-<i>ip</i>-pybox catalyst system has effectively catalyzed the reaction to afford the enantiomerically enriched branch-type allylic amines with perfect regioselectivity and high enantioselectivity

The β‑Silyl Effect on the Memory of Chirality in Friedel–Crafts Alkylation Using Chiral α‑Aryl Alcohols

Iron salt-catalyzed Friedel–Crafts alkylation of chiral α-aryl alcohols with a trimethylsilyl group was found to proceed with retention of the configuration of the hydroxyl group as a leaving group. The memory of chirality of this system stems from the β-silyl effect of the trimethylsilyl group on the carbocation intermediate

Prevalence of diverticulosis and anatomic distribution by alcohol consumption (A) and smoking index (B) (n = 2,164).

<p>Right-sided and bilateral diverticula increased significantly in line with amount of alcohol consumption (A). All distribution types of colonic diverticula increased significantly in line with smoking index (SI) (B).</p