Highly diastereoselective 1,3-dipolar cycloaddition of nonstabilized azomethine ylides to 3-nitro-2-trihalomethyl-2H-chromenes: Synthesis of 1-benzopyrano[3,4-c]pyrrolidines

Reactions of 3-nitro-2-trifluoro(trichloro)methyl-2H-chromenes, including 2-unsubstituted derivatives, with N-alkyl-α-amino acids (sarcosine, proline) and paraformaldehyde proceed diastereoselectively to give 1-benzopyrano[3,4-c]pyrrolidines in good yields as a result of a 1,3-dipolar cycloaddition of the intermediate nonstabilized azomethine ylide at the Δ3-bond of the chromene system. © 2013 Elsevier Ltd. All rights reserved

Synthesis in a gel and sorption properties of N-2-sulfoethyl chitosan

A new procedure was developed for preparation of chelate amino-containing polymer N-2-sulfoethyl chitosan by synthesis in a gel through the reaction between chitosan and sodium 2-bromoethanesulfonate, yielding a polymer with the degree of substitution of up to 0.5. The structure of the resulting polymers was confirmed by 1H NMR spectroscopy. The sorption characteristics with respect to transition and alkaline-earth metal ions were determined for the cross-linked polymers. © 2013 Pleiades Publishing, Ltd

Novel methods for synthesis and sorption properties of N,O-(2,3-dihydroxy) propylchitosan

The direct addition of glycidol to chitosan in a gel medium under exposure to ultrasound afforded the chelating aminopolymer N,O-(2,3-dihydroxy) propylchitosan with a degree of substitution up to 2.3. The sorption characteristics of the crosslinked aminopolymers with respect to boron-containing ions were estimated. © 2013 Pleiades Publishing, Ltd

Synthesis of poly[N-(2,3-dihydroxypropyl)aminostyrene], a new sorbent for boron(III) ions

A procedure was developed for preparation of poly[N-(2,3-dihydroxypropyl) aminostyrene] via successive stages of nitration, reduction, and glycidol treatment of polystyrene, which gives the polymer with a maximal degree of functionalization. The composition and structure of the intermediates and end products of the polymer-analogous reactions were characterized by elemental analysis, IR spectroscopy, and solid-state 13C NMR spectroscopy. The sorption characteristics of poly[N-(2,3-dihydroxypropyl)aminostyrene] toward boroncontaining ions were assessed. © 2013 Pleiades Publishing, Ltd.This study was financially supported by the Ural Division, Russian Academy of Sciences (project no. 12-S-3-1003) and by the Council of the President of the Russian Federation for Young Scientists and Leading Scientific Schools Supporting Grants (project no. МК-5745.2013.3)