A divergent approach to synthesize dendritic aliphatic polyester structures based on 2,2-bis(hydroxymethyl) propionic acid (bis-MPA) is described. The key building block is the anhydride of isopropylidene-2,2-bis(methoxy) propionic acid which is synthesized in high yields through self-dehydration, utilizing N,N'-dicyclohexylcarbodiimide (DCC) as reagent. The high reactivity of the anhydride toward hydroxyl groups makes the divergent synthesis of dendrimers and dendrons viable. Dendritic growth occurs in the presence of protecting groups sensitive toward hydrogenolysis, such as benzyl esters and ethers. The acetonide-protecting group is easily removed under acidic conditions using DOWEX 50W-X2 resin in methanol. Fourth-generation dendrons and dendrimers were successfully synthesized in high yields utilizing 1.3-1.5 equiv of anhydride per hydroxyl group. Common characteristics of the esterification reaction were short reaction time, mild reaction conditions, easy monitoring by NMR analysis, and simple workup. This synthetic approach opens up the possibility to utilize orthogonal protecting groups of acetonide-protected 2,2-bis(hydroxymethyl) propionic anhydride as a novel building block.

Three sets of aliphatic polyester dendrimers based on 2,2-bis(methylol)propionic acid (bis-MPA) were synthesized. Two of the sets had benzylidene terminal groups and either a trimethylolpropane or triphenolic core moiety. The last set had acetonide terminal groups and a triphenolic core moiety. Benzylidene-[G#1]-anhydride and acetonide-[G#1] -anhydride were used as the reactive building blocks in the construction of all dendrimers. The large excess of building blocks used in the coupling reactions initially resulted in considerable material loss. This waste was eliminated through the development of a recycling method. H-1 and C-13 NMR and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) analysis were used to verify the purity of all compounds. Size exclusion chromatography (SEC) was used, as well as MALDI-TOF, for molecular weight determinations. The SEC measurements were conducted with a universal calibration method and an online right-angle laser light scattering detector. Measured dendrimer molecular weights were close to their theoretical molar masses. Observations were also made of the hydrodynamic radius and intrinsic viscosity for the different dendrimers.

Dendronized, hybrid dendritic-linear polymers were synthesized by either the "graft-onto" route or by atom transfer radical polymerization (ATRP) of macromonomers. In both ways, the main chain was composed of acrylate repeating units and the dendrons were based on the aliphatic ester skeleton obtained from 2,2-bis(methylol)propionic acid (bis-MPA). ATRP of macromonomers was not a viable route for monomers with side chains larger than second-generation dendrons, which is why a combination of the two approaches was required to obtain polymers with larger side chains. The "graft-onto" route was conducted by reacting hydroxyl groups on the main chain with the acetonide-protected 2,2-bis(hydroxymethyl)propionic anhydride. The acetonide protecting group was easily removed by treating a solution of the polymer with an acidic ion-exchange resin. Dendronized polymers with 1-3 generation dendron side groups were synthesized with a maximum molecular weight of ca. 86 kDa. The products were analyzed by H-1 and C-13 NMR, SEC, and MALDI-TOF.

First to fourth generation dendritic substituents based on 2,2-bis(hydroxymethyl)propionic acid and (1R,2S,5R)-menthoxyacetic acid were attached to 2-(hydroxymethyl)pyridinooxazoline and his[4-(hydroxymethyl)oxazoline] compounds. The new ligands obtained were assessed in palladium-catalyzed allylic alkylations. The first type of ligands exhibited enantioselectivity similar to that of a benzoyl ester derivative, whereas the latter type of ligands afforded products with higher selectivity than the analogous benzoyl ester. The activity of the dendritic catalysts decreased with increasing generation.