Dendrimers, solid phase synthesi

J. Vondrasek, and M. Pisacka, Solid phase synthesis of glycopeptide dendrimers with Tn antigenic structure and their biological activities. Part I, J. Pept. Sci., 5 (1999) 46-55. 

E. A. B. Kantchev, C.-C. Chang, and D.-K. Chang, Direct Fmoc/tert-Bu solid phase synthesis of octamannosyl polylysine dendrimer-peptide conjugates, Biopolymers, 84 (2006) 232-240. 

Monaghan, Sean, Griffith-Johnson, David, Matthews, Ian and Bradley, Mark (2001). Solid-phase synthesis of peptide-dendrimer conjugates for an investigation of integrin binding. Arkivoc, 2001, (Part (x)), 46-53. http //eprints.soton.ac.uk/19576/... 

Arya et al. used solid phase synthesis to prepare immobilised dendritic catalysts with the rhodium centre in a shielded environment to mimic nature s approach of protecting active sites in a macromolecular environment (e.g. catalytic sites inside enzymes) [51], Two generations PS immobilised rhodium-complexed dendrimers, 6 and the more shielded 7, were synthesised.The PS resin immobilised rhodium-complexed dendrimers were used in the hydroformylation of styrene, p-methoxystyrene, vinyl acetate and vinyl benzoate using a total pressure of 70 bar 1 1 CO/H2 at 45 °C in CH2C12. 

In a recent report, the divergent solid-phase synthesis of nucleic acid dendrimers was also reported and the purity assessed using PAGE [24], however, the details are not included here due to space constraints. 

Arya et al. 50) immobilized similar dendrimers for the alkene hydroformylation on polystyrene (PS) beads, using solid-phase synthesis (58—60). The rhodium-catalyzed hydroformylation of styrene was investigated, and recycling experiments... 

TABLE 4.4. Solution- and Solid-Phase Synthesis of Dendrimers... 

Further materials that have been evaluated as supports for solid-phase synthesis include phenol-formaldehyde polymers [239,240], platinum electrodes coated with polythiophenes [241], proteins (bovine serum albumin) [242], polylysine [243], soluble poly (vinyl alcohol) [244], various copolymers of vinyl alcohol [4,245,246], and soluble dendrimers [14,247]. 

Scheme 13 Solid-Phase Synthesis of Heteromeric Peptide Dendrimers on a Di-K2K Dendron[2S1...

Bradley described the first solid-phase synthesis of PAMAM dendrimers in 1997 [220]. To this end, phthaloyl-protected norspermidine was coupled to aminomethyl functionalised polystyrene-polyethylene-glycol resin ((PS-PEG)-NH2) through an acid-labile linker (see Fig. 23). PAMAM dendrons were assembled by treating deprotected scaffold-bound resin 24 first with an excess of methyl acrylate... 

Bradley developed a solid-phase synthesis of peptidomimetic dendrimers using the lysine-like peptoid monomer 25 [226] which led to G1-G3 dendrimers, bearing both primary and secondary amino groups on the periphery, with promising transfection abilities and no toxicity [227] (see Fig. 25). 

Fig. 25 Solid-phase synthesis of polycationic peptoid dendrimers...

In the present context, solid-phase synthesis has been used primarily for the preparation of peptide and glycopeptide dendrimers [23]. For example, a second-generation dendrimer could be prepared by successive addition of branched polyproline building blocks to a solid phase [24]. The divergent synthesis of polyamide dendrimers on polystyrenes was accomplished [25] by Frechet el al. 1991 (cf. Fig. 2.8) [26]. PAMAM dendrons could be grown up to the fourth-... 

Oligolysine dendrimers with terminal carbohydrate structures were functionalised by solid-phase synthesis for well-defined construction of glycoclusters . Synthesis proceeded via coupling of lysine molecules. Eight amino groups are attached by peptide bonding to the periphery via a spacer-functionalised sialic acid derivative (Fig. 8.8). 

Fromont, C., Bradley, M. High-Loading Resin Beads for Solid Phase Synthesis Using Triple Branching Symmetrical Dendrimers. Chem. Commun. 2000, 283-284. 

The thermal conversion of arylhydrazones in the presence of a protic acid or a Lewis acid to form an indole ring. See OweUen, R.J., Fitzgerald, J.A., Fitzgerald, B.M. et al.. The cyclization phase of the Fischer indole synthesis. The structure and significance of Pleininger s intermediate. Tetrahedron Lett. 18, 1741-1746, 1967 Kim, R.M., Manna, M., Hutchins, S.M. et al., Dendrimer-supported combinatorial chemistry, Proc. Natl. Acad. Sci. USA 93, 10012-10017, 1996 Brase, S., Gil, C., and Knepper, K., The recent impact of solid-phase synthesis on medicinally relevant... 

The concepts surrounding the dendrimer synthesis have been lucidly presented [15, 22], The general synthetic strategy involves the repetitive alternation of a growth reaction and an activation reaction. Often these reactions have to be performed at many sites on the same molecule simultaneously. The growth reaction dictates the way by which the branching is introduced into a dendrimer. Many dendrimer syntheses rely upon traditional reactions, such as the Michael reaction or the Williamson ether synthesis while others involve the use of solid-phase synthesis or organotransition metal chemistry [1, 24]... 

Figure 12-3 Plots of the degree of polymerization versus the cumulative number of synthetic steps for various repetitive syntheses (a) conventional linear solid-phase synthesis (b) nonlinear straight-chain sequence synthesis (c) dendrimer synthesis (branching multiplicity of three) (d) double exponential den-drimer synthesis (branching multiplicity of three). In all cases, the degree of polymerization is defined as the total number of monomer units per polymer molecule.

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