Strongly orthogonal geminals: size-extensive and variational reference states

Properties and some applications of strongly orthogonal geminals (APSG) are reviewed emphasizing the motivations for their use and their shortcomings. An overview presents some techniques capable of improving the APSG function.     

Chemoselective Suzuki–Miyaura reactions of 4-trifluoromethylsulfonyloxy-6-bromocoumarin

Suzuki–Miyaura reactions of 4-trifluoromethylsulfonyloxy-6-bromocoumarin provide a convenient access to arylated coumarins. The reactions proceed with excellent chemoselectivity in favour of position 4.     

Retrovirus-mediated transduction of a cytosine deaminase gene preserves the stemness of mesenchymal stem cells

Human mesenchymal stem cells (MSCs) have emerged as attractive cellular vehicles to deliver therapeutic genes for ex-vivo therapy of diverse diseases; this is, in part, because they have the capability to migrate into tumor or lesion sites. Previously, we showed that MSCs could be utilized to deliver a bacterial cytosine deaminase (CD) suicide gene to brain tumors. Here we assessed whether transduction with a retroviral vector encoding CD gene altered the stem cell property of MSCs. MSCs were transduced at passage 1 and cultivated up to passage 11. We found that proliferation and differentiation potentials, chromosomal stability and surface antigenicity of MSCs were not altered by retroviral transduction. The results indicate that retroviral vectors can be safely utilized for delivery of suicide genes to MSCs for ex-vivo therapy. We also found that a single retroviral transduction was sufficient for sustainable expression up to passage 10. The persistent expression of the transduced gene indicates that transduced MSCs provide a tractable and manageable approach for potential use in allogeneic transplantation.     

Synthesis and application of novel carbohydrate-based ammonium and triazolium salts

The synthesis of nine new carbohydrate-based quaternary ammonium salts and two new triazolium salts starting from d-glucose has been accomplished. Our synthesis utilized the regio- and stereoselective ring opening reaction of 2,3-anhydro sugars by nucleophilic reagents to afford the key intermediates. In these new types of phase transfer catalysts, the ammonium and triazolium functions are directly attached to the carbohydrate scaffold in different positions (2-, 3-, 6-positions of the sugar). The efficiency of the altrose- and glucose-based quaternary salts were tested in the alkylation of N-(diphenyl) methylene glycine tert-butyl ester with benzyl bromide. To our knowledge this is the first example when sugar-based quaternary ammonium or triazolium salts were used successfully as phase transfer catalysts. The enantiomeric recognition ability of the synthesized salts towards racemic Mosher’s acid silver salt was also investigated by ¹⁹F NMR spectroscopy.