Polyether dendrons, Frechet-type

Preparation of Frechet-type Polyether Dendrons and Aliphatic Polyester Dendrimers by Convergent Growth An Experimental Primer... 

FRECHET-TYPE POLYETHER DENDRONS BASED ON 3,5-DIHYDROXYBENZYL ALCOHOL... 

PREPARATION OF POLYETHER DENDRIMERS BY ASSEMBLY OF FRECHET-TYPE DENDRONS AROUND A CORE... 

For this purpose, a series of Frechet-type polyether dendrons of zeroth-to third-generation containing an NCN-pincer metal complex (M = Pt, Ni) at the focal point of the wedge were prepared [69]. Their synthesis was either... 

Dendrons have also been used as the capping moieties for rotaxane cores (Figure 8). Amabilino et al. reported the Williamson coupling of the third generation Frechet-type dendrons 6 to cap polyether macrocycles threaded around linear bipyridinium oligomers.241 When the linear component consisted of multiple viologen units, 171, shuttling of the... 

In 2004, Fan and coworkers synthesized a series of chiral dendrimer hgands bearing a chiral diphosphine Pyrphos at the focal point of the Frechet-type polyether dendrons (Figure 4.6) [43]. The relationship between the primary structure of the dendrimer and its catalytic properties was established in the Rh-catalyzed hydrogenation of a-acetamidocinnamic acid (Scheme 4.5). High enantioselectivi-... 

Frechet-type polyether dendrons were complexed with Pt for use as SO2 sensor and with Ni for the Kharasch addition of CCI4 to methyl methacrylate [37]. The dendron wedges, when functionalized at their focal point, displayed adequate catalytic activity with easy recovery and good stability. 

Dendrons and dendrimers are the most intensely investigated subset of dendritic polymers. In the past decade, over 6,000 literature references have appeared dealing with this xmique class of structure-controlled polymers. The word dendrimer is derived from the Greek words dendri- (tree branch-like) and meros (part of), and was coined by Tomalia et al. about 20 years ago in the first full paper on poly (amidoamine) (PAMAM) dendrimers [47,72]. Since this early disclosure, over 100 dendrimer compositions (families) and 1,000 dendrimer surface modifications have been reported. The two most widely studied dendrimer families are the Frechet-type polyether compositions and the Tomalia-type PAMAM dendrimers. PAMAM dendil-mers constitute the first dendrimer family to be commercialized, and represent the most extensively characterized and best-understood series at this time [46]. 

J.M.J. Frechet, H. Ihre, and M. Davey. Preparation of Frechet-type polyether dendrons and aliphatic polyester dendrimers by convergent growth an experimental primer, in Dendrimers and Other Dendritic Polymers. J.M.J. Frechet and D.A. Tomaha, Eds. John Wiley Sons West Sussex, pp. 569-586, 2001. 

Ethers are chemically and coordinatively more inert than amides. Indeed, Frechet-type polyether dendrimers prepared in solution demonstrate a broad spectrum of chemical and coordinative compatibilities. Accordingly, polyether dendron synthesis on solid support was developed, initially by Bradley and coworkers and later by Portnoy and Dahan Instead of the 3,5-dihydroxy benzyl alcohol derivatives used in the soluble Frechet-type dendrimers, a more SPOS suitable 3,5-bis(hydroxymethyl)phenol unit was conceived as a building block for the dendron construction. 

Most recently. Fan s group [66] readily synthesized a series of chiral diphosphane-functionahzed Janus dendrimers (up to 16 BNIAP units, 39) by using liquid-phase organic synthesis with the third-generation Frechet-type polyether dendron as the soluble support. The ruthenium complexes of these dendritic ligands were... 

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