Polymer supports synthesis

Polymer-supported synthesis of natural macrocyclic lactones and other 0-heterocycles 99AG(E)1903. 

These conceptual goals are attained by several combinatorial methods and tools. Characteristic for combinatorial chemistry is the synthesis on solid support or by polymer-supported synthesis, allowing for much higher efficiency in library production. Synthesis can be conducted either in automated parallel synthesis or by split-and-recombine synthesis. Centerpieces of combinatorial methods further include specific analytical methods for combinatorial... 

Solid Phase Synthesis Versns Polymer-Supported Synthesis in Solution... 

Scheme 7.12 Reaction strategies for the polymer-supported synthesis of dialkylaminopropenones.

Table 16 Traceless polymer-supported synthesis of 4,5-disubstituted 3-amino-1,2,4-triazole derivatives (Scheme 5)...

Highly efficient modifications of Mukaiyama s procedure, convenient for combinatorial syntheses, were reported recently, namely the polymer-supported synthesis of isoxazolines via nitrile oxides, starting from primary nitroalkanes, in a one-pot process (75) and by microwave activation of the process (73). 

M. A. Marx, A.-L. Grillot, C. T. Louer, K. A. Beaver, P. A. Bartlett, Synthetic Design for Combinatorial Chemistry. Solution and Polymer-Supported Synthesis of Polycyclic Lactams by Intramolecular Cyclization of Azo-methine Ylides , J. Am. Chem Soc. 1997,119, 6153-6167. 

High selectivity and substrate specificity of glycosyl transferases make them valuable catalysts for special linkages in polymer-supported synthesis. There is, however, still a rather limited set of enzymes available to date, and the need to synthesize a variety of natural and non-natural oligosaccharides prevails. Particularly with regard to combinatorial approaches, chemical solid-phase oligosaccharide synthesis promises to meet the demands most effectively. 

Scheme 9.1 Comparison of one-phase and two-phase polymer-supported synthesis of oligosaccharides. Continued next page.

Scheme 9.2 Comparison of polymer-supported synthesis of oligosaccharides between the attachment of a polymer to a glycosyl donor and a glycosyl acceptor.

Scheme 9.3 Polymer-supported synthesis of oligosaccharides employing a hydrophobic handle attached to the growing chain in the last step of the synthetic sequence. The handle permits separation of the majority of failure sequences accumulated during the synthesis.

Polymer-supported synthesis of S-alkyl and S-aryl dithiocarbamates (Table 4.25)... 

TABLE 4.25 Polymer-supported synthesis of alkyl dithiocarbamates R.NCS.SR1 ... 

Chiral benzamides I and the pyrrolobenzodiazepine-5,11-dio-nes n have proven to be effective substrates for asymmetric organic synthesis. Although the scale of reaction in our studies has rarely exceeded the 50 to 60 g range, there is no reason to believe that considerably larger-scale synthesis will be impractical. Applications of the method to more complex aromatic substrates and to the potentially important domain of polymer supported synthesis are currently under study. We also are developing complementary processes that do not depend on a removable chiral auxiliary but rather utilize stereogenic centers from the chiral pool as integral stereodirectors within the substrate for Birch reduction-alkylation. 

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