in Wiley Online Library (wileyonlinelibrary.com).The enantioselective extraction of hydrophobic oxybutynin (OBN) enantiomers by hydrophilic b-cyclodextrin (b-CD) derivatives was studied. The efficiency of extraction depends strongly on a number of process variables such as types of organic solvents and b-CD derivatives, concentration of selector, pH, and temperature. The experimental data were described by a reactive extraction model with a homogeneous aqueous phase reaction of R,S-OBN with b-CD. Important parameters of this model were determined experimentally. The physical distribution coefficients for molecular and ionic OBN were 4.96 Â 10 À3 and 9.52, respectively. The equilibrium constants of the complexation reactions were 1770 and 1340 L/mol for S-and R-OBN, respectively. By modeling and experiment, an optimal extraction condition with pH of 5 and HP-b-CD concentration of 0.1 mol/L was obtained with enantioselectivity (a) of 1.26, which was close to the theoretical maximum of 1.32 and performance factor (pf i ) of 0.036. The model was verified experimentally with excellent results.

No abstract

Multistage enantioselective liquid–liquid extraction (ELLE) in centrifugal contactor separators was developed for separation of enantiomers. Performance of the process was evaluated by product purity (enantiomeric excess, ee) and yield (Y). Enantioselective liquid–liquid extraction of α-cyclohexyl-mandelic acid (α-CHMA) enantiomers with hydrophilic hydroxyphenyl-β-cyclodextrin as extractant (C) was performed in a countercurrent cascade of 10 centrifugal contactor separators (CCSs) at 278 K to investigate the influence of the operation variables including phase ratios and concentrations on extraction efficiency. On the basis of a single stage equilibrium model and the law of conservation of mass, a multistage equilibrium model of enantioselective liquid–liquid extraction was developed to investigate the influence of changes in the process parameters such as phase ratios and concentrations on extraction efficiency. The multistage model predicted the experimental data accurately and was applied to optimize the symmetrical separation of α-CHMA enantiomers. By modeling, the minimum number of stages for eeeq > 97% and eeeq > 99% was predicted as 42 and 48, respectively.

A novel visible-light promoted sulfonylation/ipso-cyclization of N-arylpropiolamides with aromatic amines and DABCO·(SO2)2 to synthesize various sulfonated spiro[4,5]trienones is reported.

A novel visible-light photoredox-catalyzed dual C–C bond cleavage of methylenecyclopropanes and cycloketone oximes for accessing 2-cyanoalkylsulfonated 3,4-dihydronaphthalenes is established.

The ring-opening/cyclization of cyclopropane derivatives has drawn great attention in the past several decades. In this review, recent efforts in the development of oxidative radical ring-opening/cyclization of cyclopropane derivatives, including methylenecyclopropanes, cyclopropyl olefins and cyclopropanols, are described. We hope this review will be of sufficient interest for the scientific community to further advance the application of oxidative radical strategies in the ring-opening/cyclization of cyclopropane derivatives.

A recycling high-speed countercurrent chromatography protocol was proposed for the enantioseparation of brompheniramine by employing β-cyclodextrin derivatives as a chiral selector. The two-phase solvent system of n-hexane/isobutyl acetate/0.10 mol/L phosphate buffer solution with a volume ratio of 2:4:6 was selected by a series of extraction experiments. Factors that affected the distribution of the enantiomers over the two-phase system (e.g., the type and concentration of β-cyclodextrin derivatives = pH value of the aqueous solution, and the separation temperature) were also investigated. In addition, the theory of thermodynamics is applied to verify the feasibility of the enantioseparation process and the corresponding results demonstrate that this separation process is feasible. The optimized conditions include carboxymethyl-β-cyclodextrin concentration of 0.010 mol/L, pH of 7.5, and temperature of 5°C. Under the optimal conditions, the purities of both monomer molecules were over 99%, and the recovery yields were 88% for (+)-brompheniramine and 85% for (-)-brompheniramine, respectively.

A novel visible-light-catalyzed sulfonylation/arylation of carbon–carbon σ-bond with sulfonyl chlorides for the synthesis of 3-sulfonylated 1,2-dihydronaphthalenes is developed. This difunctionalization proceeds via a sequence of CC bond sulfonylation, C–C σ-bond cleavage, and intramolecular cyclization, and the experiment result shows that the C–C σ-bond difunctionalization reaction includes a radical process. This strategy provides a simple and convenient route for difunctionalization of C–C bonds with an aromatic carbon and a sulfonyl radical by one-pot construction of a C–S bond and a new C–C bond.