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Ordered molecular self-assembly of glycoamphiphiles has been regarded as an attractive, practical and bottom-up approach to obtain stable, structurally well-defined, and functional mimics of natural polysaccharides. This study describes a versatile and rational design of carbohydrate-based hydrogelators through N,N’-substituted barbituric acid-mediated Knoevenagel condensation onto unprotected carbohydrates in water. Amphiphilic N-substituted β-C-maltosylbarbiturates self-assembled into pH- and calcium-triggered alginate-like supramolecular hydrogel fibers with a multistimuli responsiveness to temperature, pH and competitive metal chelating agent. In addition, amphiphilic N,N’-disubstituted β-C-maltosylbarbiturates formed vesicle gels in pure water that were scarcely observed for glyco-hydrogelators. Finally, barbituric acid worked as a multitasking group allowing chemoselective ligation onto reducing-end carbohydrates, structural diversity, stimuli-sensitiveness, and supramolecular interactions by hydrogen bonding.

PROBLEM TO BE SOLVED: To provide a method for preparing a urea compound by fixing carbon dioxide. SOLUTION: This invention relates to a method for preparing the urea compound by reacting a carbon dioxide raw material with an amine compound raw material by a reaction system with a medium containing at least carbon dioxide as a reaction medium, chemically fixing carbon dioxide to the amine compound, and synthesizing the urea compound corresponding to the amine compound raw material. This invention also relates to a method for preparing the urea compound by synthesizing the urea compound corresponding to the amine compound with water in which carbon dioxide is dissolved or carbon dioxide containing water as the reaction medium. According to this invention, the corresponding urea compound can be synthesized at a high selection rate from the amine compound by the carbon dioxide fixation process. COPYRIGHT: (C)2012,JPOandINPIT

Alkyl isocyanates react in the presence of triethylsilane and catalytic amounts of to give 1,3,6,8,10-pentaazaspirodecane-2,4,7,9-tetrones.The novel spiroheterocycles consist of alternating CO and NR building units.Diisocyanates result in the formation of duroplastic polymers with CO-NR sequence and spiro-C ties.