Design and Synthesis of Novel Polyester-type Dendrimers Having Cell Recognition Ability.

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The purpose of this research project is design and synthesis of a new polyester-type dendritic skeleton that is biodegradable and applicable to a dendritic caged compound, a new drag delivery system.The building block was synthesized using acetoacetic acid ester synthesis of benzyl acetoacetate and t-butyl acrylate. 2:1 addition product was obtained > 90% after addition, hydrogenolysis and decarboxylation. The optimum reaction conditions for dendrimer synthesis were examined. The dendrimers from [G1, MW: 821] to [G5, MW: 15327] were obtained in an average more than 80% yield by divergent method using iterative reaction using [deprotection by HCOOH then condensation by EDCI/DMAP]. They were easily purified by silica gel column chromatography using hexane and ethyl acetate (1:1 v/v). The dendrimers thus obtained were colorless viscous liquid that was soluble in organic solvents such as dichloromethane or ethyl acetate. The structural characterization was carried out by elemental analysis, NMR, and ESI-MS. ^1H and ^<13>C NMR signals were accurately assigned using versatile NMR measurement techniques such as NOESY, ROESY, HMBC. Also, the conformational mobility of outer and inner shells of these dendrimers were assessed by ^<13>C NMR relaxation time (T_1).For the application of these dendrimers, tetraethylen glycol, 1-pirenyl, or sugar derivatives were indroduced at their peripbhery. Their characterization was now in progress.