Synthesis and characterisation of peripherally functionalised dendritic molecules

A number of peripherally functionalised dendritic molecules were synthesised in almost quantitative yield by a synthetic method involving the reaction between amines and isocyanates. The peripheral functional groups were incorporated by preparing a number of branched subunits, based on tris(hydroxymethyl) aminomethane (TRIS), 1, possessing three nitro, methoxy, methyl or maleimide terminal functionalities. Attachment of these branched units to the core molecules 4,4'-methylenebis(phenyl isocyanate) 13 and 1,3,5-benzene triisocyanate 20 afforded the corresponding dendritic molecules possessing 6 or 9 peripheral functional groups. Functional group conversions on the dendritic molecules have been successfully carried out, including hydrogenation of the terminal nitro to the corresponding amine and cleavage of the methoxy ether to give the corresponding phenol.