Efficient Synthesis of New Nucleoside Analogues with a Methylenecyclobutane Unit

Synthesis of eight nucleoside analogues 4–11 with a methylenecyclobutane unit is described. Wittig reaction with 2‐hydroxymethylcyclobutanone 12 gave a mixture of Z (13) and E (14) derivatives, which was separated before functional modifications. The heterocyclic moieties were introduced via a Mitsunobu reaction either on the saturated chain or on the unsaturated chain. When adenine was used in this reaction, only the N‐9 substitution products were obtained. Removal of the protecting groups provided the target products.     

Synthesis of 4-Benzidinyl Butyric Acid: A Key Intermediate for Antibodies Production Against Benzidin

a four-step synthesis of monoalkylated benzidin is reported for immunogen preparation against benzidin dye. Use of 10% H₂SO₄/ dioxan for N-Boc cleavage avoids the cyclisation of 4-benzidinyl butyric acid into the corresponding lactam observed with the classical TFA/ CH₂Cl₂ system.     

Cyclodextrin-Containing Polymers for Gene Delivery

Cyclodextrin-containing polymers are now being explored as vehicles for delivering nucleic acids into cells. The structures of the cyclodextrin-containing polycations affect the nucleic acid delivery efficiencies and their toxicities. Of interest is the fact that the cyclodextrin-containing polymers reveal lower toxicities than polymers that lack the cyclodextrins. The cyclodextrins endow the nucleic acid delivery vehicles with the ability to be modified by compounds that form inclusion complexes with the cyclodextrins, and these modifications can be performed without disruption of the polymer-nucleic acid interactions. Thus, cyclodextrin-containing polymers provide unique properties for gene delivery.     

Binding affinities of commonly employed sensitizers of viral inactivation

Methylene blue (MB), riboflavin (RB) and psoralen sensitizers (4' aminomethyl-4,5',8-trimethylpsoralen [AMT] and derivatives) are under study as sensitizers of viral inactivation of blood products such as plasma proteins, platelets and red cells, all of which lack genomic nucleic acid. To predict where these sensitizers accumulate in viruses and in cells, their relative affinities for calf thymus DNA, neutral and negatively charged phospholipids and albumin were determined by dialysis. MB has a strong affinity for nucleic acid and negatively charged phospholipid, but little affinity for albumin or neutral phospholipid. RB has modest affinity for nucleic acid and little affinity for albumin or either phospholipid. AMT has substantial affinity for nucleic acid, neutral and negatively charged phospholipids and albumin. Neither AMT nor RB binds to poly G, although MB has some affinity for this polymer. Evidence of association of RB with guanosine monophosphate, adenosine monophosphate and tryptophan methylester hydrochloride in PBS buffer in the presence and absence of formamide was obtained from nonlinear Stern-Volmer plots and shifts in the ground state absorption spectrum of RB.     

Solvent-Free Condensation of Methyl Pyridinium and Quinolinium Salts with Aldehydes Catalyzed by DBU

Methylpyridinium and methylquinolinium salts were condensed under solvent-free conditions with aromatic aldehydes in the presence of 1,8-diazabicyclo[5.4.]undec-7-ene (DBU) as catalyst, by grinding at room temperature. The products are dyes or useful intermediates. The DBU can be easily recycled and reused.     

Rapid analysis of triterpenic acids by liquid chromatography using porous graphitic carbon and evaporative light scattering detection

An original system which uses Porous Graphitic Carbon as support and a mixture of organic solvents as mobile phase is proposed for the analysis of triterpenic acids by liquid chromatography. The separation of betulinic acid, ursolic acid, oleanolic acid, and 18alpha- and 18beta-glycyrrhetinic acids was carried out within a short time and monitored by evaporative light scattering detection as universal detection method. Molecular modelling studies show that the main contribution to the selectivity comes from the electrostatic interaction characterised by the dipole moment of the products.     

DEUSS: a perdeuterated poly(oxyethylene)-based resin for improving HRMAS NMR studies of solid-supported molecules

A novel resin called DEUSS (perdeuterated poly(oxyethylene)-based solid support) has been prepared by anionic polymerization of deuterated [D4]ethylene oxide, followed by cross-linking with deuterated epichlorohydrin. DEUSS can be suspended in a wide range of solvents including organic and aqueous solutions, in which it displays a high swelling capacity. As measured by proton HRMAS of the swollen polymer, the signal intensity of the oxyethylene protons is reduced by a factor of 110 relative to the corresponding nondeuterated poly(oxyethylene)poly(oxypropylene) (POEPOP) resin, thus facilitating detailed HRMAS NMR studies of covalently linked molecules. This 1H NMR invisible matrix was used for the solid-phase synthesis of peptides, oligoureas, and a series of amides as well as their characterization by HRMAS NMR spectroscopy. On-bead NMR spectra of high quality and with resolution comparable to that of liquid samples were obtained and readily interpreted. The complete absence of the parasite resin signals will be of great advantage, for example, for the optimization of multistep solid-phase stereoselective reactions, and for the conformational study of resin-bound molecules in a large variety of solvents.