Molecular diversity of novel amino acid based dendrimers

We have expanded the recently introduced methodology for the preparation of a novel amino acid based dendrimer in order to be able to synthesize a diversity of dendrimers. For this purpose different hydroxybenzoic acids and amino alcohols were used to prepare the required monomers, necessary for construction of the respective dendrimers. © 1997 Elsevier Science Ltd. In the preparation of the first molecules to be named (starbust) dendrimers advantage was taken from the formation of the stable amide bond, [1] leading to defined macromolecules ultimately containing several hundreds of amide bonds, i.e. as many as there are present in proteins. Not surprisingly, a significant number of subsequent dendrimer syntheses featured the repeated formation of amide bonds in their construction. [2] In a previous communication we have described the efficient synthesis of a novel amino acid based dendrimer [3]. The BOP coupling reagent, [4] normally used in high-yielding and clean syntheses of peptides, was employed for the preparation of this particular dendrimer. In addition to the development of a reliable strategy for efficient construction of novel amino acid based dendrimers, it was our wish to introduce a considerable degree of molecular diversity in our dendrimer synthetic strategy, so that it could be employed for the preparation - in the future also by combinatorial methods - of dendrimers with a variety of branching patters, interior cavity size, interior and surface functionality. We realized that a significant molecular diversity of dendrimers could be generated by using aromatic residues bearing varying numbers of amino and carboxylic acid functions. On their turn, these amino acid building blocks can be derived from various commercially available hydroxy benzoic acid derivatives and amino alcohol derivatives, which are either commercially available or easily synthetically accessible. A few representative examples of amino acid based dendrimer monomers containing a substituted aromatic residue are schematically depicted in Fig. 1. From this figure it also follows that already twelve different (homo)dendrimer monomers are possible by combination of the four depicted hydroxy benzoic acid derivatives and the three shown amino alcohols

Synthesis of a novel amino acid based dendrimer

An easy accessible dendrimer monomer 3,5-bis(2-tert-butyloxycarbonyl aminoethoxy) benzoic acid methyl ester 1 was designed. The monomer was converted to both the “surface” and “braching” monomer in a versatile synthesis of a novel amino acid based dendrimer by the covergent method, using the well established and high-yielding BOP-peptide coupling method

Semisynthesis of some 7-deoxypaclitaxel analogs from taxine B

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Synthetic receptors based on peptidosulfonamide peptidomimetics

We have synthesized tweezer-like receptor molecules based on peptidosulfonamide peptidomimetics. These compounds were screened for binding against a ∼25,000 member encoded tripeptide library. One of these synthetic receptors showed a remarkable binding selectivity

An Approach to Canthine Derivatives Using the Intramolecular Pictet-Spengler Condensation

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Synthesis and catalytic application of amino acid based dendritic macromolecules

The use of amino acid based dendrimers as molecular scaffolds for the attachment of catalytically active organometallic Ni ''pincer'' complexes, via a urea functionality, is described; the dendrimer catalysts have comparable activity to their mononuclear (NCN)NiX analogues