Functionalized Silver-Ion-Mediated α-dC/β-dC Hybrid Base Pairs with Exceptional Stability: α-d-5-Iodo-2′-Deoxycytidine and Its Octadiynyl Derivative in Metal DNA

Silver-mediated α-dC–Ag⁺–β-dC hybrid base pairs decorated with 5-iodo- or 5-octadiynyl residues are well accommodated in duplex DNA. A strong T_m increase and favorable thermodynamic data for duplex DNA were observed after addition of silver ions. The phenomenon is particularly obvious when both nucleobases of the base pairs are functionalized. Neither the position of the base pair, nor the type of 5-substituent had a negative influence. On the contrary, functionalization of conventional silver-mediated β-dC–Ag⁺–β-dC homo base pairs showed a negative impact induced by the bulky substituents. To this end, cytosine modified 12-mer oligodeoxynucleotides were prepared by solid-phase synthesis employing new α-anomeric 2′-deoxycytidine phosphoramidites. A multigram scale synthesis was developed for 5-iodo-α-d -2′-deoxycytidine ( 1 ) employing the direct glycosylation of cytosine with Hoffer's α-d -halogenose followed by separation of anomeric DMT nucleosides. Regarding base-pair stability and functionalization silver-mediated α/β-dC hybrid base pairs were found to be superior to β/β-dC homo pairs. According to their extraordinary properties, they might find applications in DNA diagnostics, material science, or nanotechnology.     

Nucleophilic Vinylic Substitution in Perfluoroacylchromenes. Diastereoselective Synthesis of Push–Pull Enamino Ketones

Russian Journal of Organic Chemistry - The reactions of 2-perfluoroacyl-1H-benzo[f]chromenes and 6,7-dimethyl-3-trifluoroacetyl-4H-chromene with primary aliphatic amines and ammonia afforded a...     

Electrochemical reduction of functional groups in the cathodic exfoliation of an ethylene-vinyl acetate copolymer

A study was carried out on the electrochemical processes involving the functional groups of an ethylene-vinyl acetate copolymer upon its cathodic exfoliation from metal. Electron transfer to the polymer is facilitated by the activation effect of an adhesion interaction with the metal.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 30, No. 6, pp. 346–349, November–December, 1994.     

Transamination of 2-piperidinochromanes with (het)arylamines as a convenient route to 2-(het)arylaminochromanes

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Mass Transfer of Salt Ions in an Electromembrane System with Violated Electroneutrality in the Diffusion Layer: The Effect of a Heterolytic Dissociation of Water

The effect of water dissociation on the mass transfer of salt ions is studied with allowance for the space charge. The Kharkats problem, which considers exaltation of the limiting diffusion current, and the Rubinstein problem, which accounts for violation of the electroneutrality condition in a membrane system, are generalized.