Lipase as a Chiral Selector Immobilised on Carboxylated Single-Walled Carbon Nanotubes and Encapsulated in the Organic Polymer Monolithic Capillary for Nano-High Performance Liquid Chromatography Enantioseparation of Racemic Pharmaceuticals.

Herein, we report the preparation of lipase immobilised on single-walled carbon nanotubes (SWCNTs) as an enantioselector for capillary monolithic columns and their application in the chiral separation of racemic pharmaceuticals. The columns were prepared through the encapsulation of functionalised SWCNTs (c-SWCNTs) within an organic monolithic polymer, followed by the immobilisation of lipase over the obtained monolith, over a three-day (L1) and five-day (L2) period. The prepared columns were tested for the enantioselective nano-HPLC separation of 50 racemic drugs. A suitable resolution was achieved for 25 drugs using nano-RP-HPLC conditions for both the L1 and L2 capillaries, while no specific resolution was detected under normal-phase HPLC conditions. The developed c-SWCNT-lipase-based polymeric monolithic capillaries are a promising expansion for separating pharmaceutical enantiomers' using nano-HPLC.

An insight into chiral monolithic stationary phases for enantioselective high-performance liquid chromatography applications.

In this review, three main classes of chiral monolithic stationary phases, namely silica-, organic polymer-, and hybrid-based monolithic stationary phases, are covered. Their preparations, applications, and advantages compared with the conventional-packed and open-tubular capillary columns are discussed. A detailed description of the different types and techniques used for the introduction of chiral selectors into the monolithic matrices such as immobilization, functionalization, coating, encapsulation, and bonding. Special emphasis is given to the recent developments of chiral selectors in HPLC monolithic stationary phases during the past 18 years.

Enoldiazosulfones for Highly Enantioselective [3 + 3]-Cycloaddition with Nitrones Catalyzed by Copper(I) with Chiral BOX Ligands.

Enoldiazosulfones undergo [3 + 3]-cycloaddition with nitrones when catalyzed by copper(I) catalysts, but not with dirhodium(II) catalysts. Under mild reaction conditions with chiral bisoxazoline ligands, copper(I) catalysts produce 1,2-oxazine-sulfone derivatives in high yields and enantioselectivities. Dirhodium(II) catalysts form stable donor-acceptor cyclopropenes that undergo uncatalyzed [3 + 2]-cycloaddition reactions with nitrones.

Trimethyl-ß-cyclodextrin-encapsulated monolithic capillary columns: Preparation, characterization and chiral nano-LC application.

Trimethylated-ß-cyclodextrin (TM-ß-CD) was encapsulated within several polymer monolithic capillary columns for reversed-phase chiral nano-liquid chromatography (nano-LC). The monolithic phases were prepared using the one-pot in situ copolymerization of ethylene glycol dimethacrylate (EDMA), glycidyl methacrylate (GMA) monomers and 1-propanol, 1,4-butanediol as progenic solvents in presence of TM-ß-CD solution within fused silica capillaries (150µm I.D.). The obtained chiral monolithic stationery phases were characterized by scanning electron microscopy (SEM), N2 adsorption/desorption isotherms, wide angle x-ray diffraction (WAXRD), thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The materials characterization demonstrated that monolithic phases with higher concentration of TM-ß-CD have relatively larger surface area, smaller pore size and larger total pore volume compared to those with lower concentration TM-ß-CD. The prepared columns were tested for their enantioseparation efficiency of a range of racemic pharmaceuticals. The screening results demonstrated the potential of functionalizing polymer monolithic stationary phases with TM-ß-CD using the in situ encapsulation approach.

Design and Synthesis of Novel Chiral Dirhodium(II) Carboxylate Complexes for Asymmetric Cyclopropanation Reactions.

A novel approach to the design of dirhodium(II) tetracarboxylates derived from (S)-amino acid ligands is reported. The approach is founded on tailoring the steric influences of the overall catalyst structure by reducing the local symmetry of the ligand's N-heterocyclic tether. The application of the new approach has led to the uncovering of [Rh2 (S-tert PTTL)4 ] as a new member of the dirhodium(II) family with extraordinary selectivity in cyclopropanation reactions. The stereoselectivity of [Rh2 (S-tert PTTL)4 ] was found to be comparable to that of [Rh2 (S-PTAD)4 ] (up to >99 % ee), with the extra benefit of being more synthetically accessible. Correlations based on X-ray structures to justify the observed enantioinduction are also discussed.

Cyclodextrin-Functionalized Monolithic Capillary Columns: Preparation and Chiral Applications.

In this review, the recently reported approaches for the preparation of cyclodextrin-functionalized capillary monolithic columns are highlighted, with few applications in chiral separations using capillary liquid chromatography (CLC) and capillary electrochromatography (CEC). Chirality 28:97-109, 2016. © 2015 Wiley Periodicals, Inc.

Chiral dirhodium(II) carboxylates and carboxamidates as effective chemzymes in asymmetric synthesis of three-membered carbocycles.

In this review the recent advances in the utilization of two of the most important classes of dirhodium(II) paddlewheel complexes, dirhodium(II) carboxylates and carboxamidates, as chemzymes in inter- and intramolecular asymmetric cyclopropanation, as well as cyclopropenation reactions are discussed.

Rh2 (S-1,2-NTTL)4 : A novel Rh2 (S-PTTL)4 analog with lower ligand symmetry for asymmetric synthesis of chiral cyclopropylphosphonates.

A new series of dirhodium(II) tetracarboxylate was derived from N-1,2-naphthaloyl-(S)-amino acid ligands. In terms of enantioselectivity, Rh2 (S-1,2-NTTL)4 () derived from N-1,2-naphthaloyl-(S)-tert-leucine, was the best-performing catalyst among the new series in the enantioselective synthesis of cyclopropylphosphonate derivatives (up to >99% enantiomeric excess). A predictive model was proposed to justify the observed high enantiomeric induction exhibited by Rh2 (S-1,2-NTTL)4 with donor-acceptor phosphonate carbenoids.

Current trends in separation of plasmid DNA vaccines: a review.

Plasmid DNA (pDNA)-based vaccines offer more rapid avenues for development and production if compared to those of conventional virus-based vaccines. They do not rely on time- or labour-intensive cell culture processes and allow greater flexibility in shipping and storage. Stimulating antibodies and cell-mediated components of the immune system are considered as some of the major advantages associated with the use of pDNA vaccines. This review summarizes the current trends in the purification of pDNA vaccines for practical and analytical applications. Special attention is paid to chromatographic techniques aimed at reducing the steps of final purification, post primary isolation and intermediate recovery, in order to reduce the number of steps necessary to reach a purified end product from the crude plasmid.

Synthesis of some novel D-glucuronic acid acetylated derivatives as potential anti-tumor agents.

A structurally diverse series of Δ(4,5) -uronamide derivatives have been chemically synthesized starting from D-glucuronic acid itself by means of acetylation, activation, amide bond formation and base-catalyzed elimination protocols. Structure elucidation for all products along with optimization of the synthetic steps is described. The synthesized compounds were evaluated for their in-vitro anti-tumor activity against MCF-7, TK-10 and UACC-62 cell lines. The compounds 5, 11, 13, 15 and 16 were the most active against TK-10 cell line. On the other hand, the most active compounds against the MCF-7 cell line were 11 and 15. However, compounds 5, 7, 11, 13, 15 and 16 were the most active against the UACC-62 cell line.

Design, synthesis and antitumor activity of novel D-glucuronic acid derivatives.

A series of D-glucuronic acid derivatives were chemically synthesized including acetylated and deacetylated glucuronamides, as well as N-glucuronides starting from the D-glucuronic acid itself by means of protection/deprotection, activation and condensation protocols. Structure elucidation of all products along with optimization of the synthetic steps is described. The synthesized compounds were evaluated for their in vitro antitumor activity against MCF-7, TK-10 and UACC-62 cell lines. The compounds 4, 5, 7, 8, 14, 16 and 18 were the most active against TK-10 cell line. On the other hand, the most active compounds against the MCF-7 cell line were 9, 18 and 20. However, compounds 7-10 13-15 and 17 were the most active against the UACC-62 cell line.