Hydroxy-Functionalized Dendritic Building Blocks

Abstract

A convenient and practical multi‐gram procedure for the synthesis of second‐ (G2; 4a, 5a, 5d) and third‐generation (G3; 6a) dendrons with orthogonally protected functional groups in the periphery (hydroxy) and at the focal point (carboxylic acid) is described. It uses the amply available first‐generation dendrons with amine and carboxylic ester functions (1) and tetrahydropyranyl‐protected hydroxy and carboxylic acid functions (2b, 3), respectively, which are connected via amides by peptide methods. Purification is either done by recrystallization or simple filtration through silica gel and yields the products as analytically pure materials on a several‐gram scale (even for G3). ‘The dendrons’ protective groups are proven to be orthogonal (500‐MHz NMR) which makes them useful components (building blocks) of a future dendron construction kit for a versatile synthesis of, for example, dendronized polymers.

Convergent Dendrons and Dendrimers: from Synthesis to Applications

“…A wide variety of other convergent syntheses have been developed for the preparation of dendritic poly(amides), 132,153-160 poly(esters), 161,162 poly-(urethanes), 163,164 poly(carbonates), 165 poly(aryl ethers), [166][167][168][169] poly(arylamines), [170][171][172][173] poly(aryl ketones), 174 poly(aryl alkynes), 175 poly(aryl methanes), 176 poly(arylammonium) salts, 177 poly (thioureas), 178 poly-(ether imides), 179 poly(keto ethers), [180][181][182] poly(amine ethers), 183 poly(amino esters), 184 poly(amide ethers), [185][186][187][188][189] poly(pyridyl amides), 190 poly(uracils), 191 poly(triazenes), 192,193 poly(saccharides), 194 poly(glycopeptides), 195 and poly(nucleic acids). 196 In addition, chiral dendrimers 197,198 including amide, [199][200][201] ether, 96-108 and ester 202 linkages, and organometallic dendrimers, [203][204][205][206][207] including silicon, 208 germanium, 209 palladium, 210 and platinum 211-214 containing rep...…”

On the Improved Accessibility of Dendronized Macromonomers with Peripheral Protected Amine Groups

“…In order to engineer the properties of dendronized polymers, it is desirable to have access to surface functionalized representatives. Recently, we described the synthesis of dendronized polystyrenes with hydroxy [6,7] and amino groups [7,8] in the periphery, as well as glucose decorated dendronized polyacrylates. [9] To more broadly explore the possibilities of "surface" patterning, including the area where multivalency [10] comes into play, we looked for dendronized polymers with orthogonally protected functional groups.…”

“…All monomers are based on methacrylate (and acrylate) polymerizable units and carry the same 1,4-benzenedimethylene spacer. The branching units may be unsymmetrical (6), or symmetrical (15). Branching units are connected to one another, and to the polymerizable unit carrying the spacer (7 and 8), by conventional amide coupling chemistry (see below).…”

Polyester Dendrimers

“…Different types of dendrimers, called alternating dendrimers here, can be produced if orthogonal coupling methods are used in alternation to produce dendrimers with different functional groups joining alternate dendrons [40,73,[85][86][87][88][89][90][91][92][93][94][95][96][97][98][99][100][101]. The first example of this strategy incorporating ester units, shown in Schemes 4 and 5, used the Mitsunobu reaction to form esters [102] and Sonagashira coupling as its orthogonal partner [102].…”