Polyfunctionalized products

Functionalized propargyUc organolithium compounds are probably involved in the transformation of chlorinated ethers or amines 211 into polyfunctionalized products 212, which were achieved through a DTBB-catalyzed lithiation under Barbier-type reaction conditions (Scheme 73). The reaction failed for the corresponding thioethers (Y =... 

A special case of functionalized aryllithium reagents appears when the corresponding aryl group bears a ketal moiety at the benzylic position due to the lability of the benzyUc carbon-oxygen bonds. However, working under Barbier-type conditions and using naphthalene (10%) as the electron carrier catalyst, the reaction of chlorinated materials 242 afforded, after hydrolysis with water, the corresponding polyfunctionalized products 243 (Scheme 81). ... 

Asymmetric C-C bond formation is the most important and most challenging problem in synthetic organic chemistry. In Nature, such reactions are facilitated by lyases, which catalyze the addition of carbonucleophiles to C=0 double bonds in a manner that is classified mechanistically as an aldol addition [1]. Most enzymes that have been investigated lately for synthetic applications include aldolases from carbohydrate, amino acid, or sialic acid metabolism [1, 2]. Because enzymes are active on unprotected substrates under very mild conditions and with high chemo-, regio-, and stereoselectivity, aldolases and related enzymes hold particularly high potential for the synthesis of polyfunctionalized products that are otherwise difficult to prepare and to handle by conventional chemical methods. 

Polyfunctionality of the reactants is not sufficient in itself to assure formation of polymer the reaction may proceed intramolecularly with the formation of cyclic products. For example, hydroxy acids when heated yield either lactone or linear polymer (or both),... 

The selective functionalization of saccharose and sorbitol with fatty acids for the construction of a perfect amphiphilic structure cannot be realized in simple technical processes because of the polyfunctionality of the molecule. This is why the products offered on the market contain different amounts of mono-, di- and... 

Polynuclear Phenol—Glycidyl Ether-Derived Resins. This is one of the first commercially available polyfunctional products. Its polyfunctionality permits upgra ding of thermal stability, chemical resistance, and electrical and mechanical properties of bisphenol A—epoxy systems. It is... 

When pyrimidinone 3 is allowed to react with 1,3-dicarbonyl compounds 19 in the presence of piperidine, polyfunctionalized pyridones 12 are prepared (Table 12) [62], In the present reaction, /3-keto esters 19b and 19i, diester 19k and cyanoacetate 191 are usable as the reagent to give corresponding pyridones 12, however /J-dikc tones 19c and 19j affords no RTF product, which is due to further decomposition of produced pyridones 12c and 12j under the employed conditions. 

Fell also described the hydroformylation of fatty acids with heterogenized cobalt carbonyl and rhodium carbonyl catalysts [37]. The products of the reaction with polyunsaturated fatty acids were, depending on the catalyst metal, poly- or monoformyl products. The catalyst carrier was a silicate matrix with tertiary phosphine ligands and cobalt or rhodium carbonyl precursors on the surface. The cobalt catalyst was applied at 160-180°C and gave mostly monofunctionalized fatty acid chains. With linoleic acid mixtures, the corresponding rhodium catalyst gave mono- and diformyl derivatives. Therefore, the rhodium catalyst was more feasible for polyfunctionalized oleocompounds. The reaction was completed in a batch experiment over 10 h at 100 bar and 140°C rhodium leaching was lower than 1 ppm. 

A wider available panel of purified enzymes, or of characterized microorganisms performing a particular biotransformation, could increase the potential of this technique. Its main limitations are the stability of the enzymes, both to organic solvents and to different temperatures, which could be significantly improved by their immobilization on a solid support, and the solubility in aqueous media required in most cases for the biotransformation substrates. Anyway, the extreme usefulness of combinatorial biocatalysis for specific classes of products (complex natural products, polyfunctionalized chiral scaffolds) has already been assessed. 

The electrostatic attraction between oppositely charged molecules is an adjustable driving force for structured material construction. The current synthetic routes of polymer production often offer many variations in size, topology, functionality and polydispersity. An electrostatically driven assembly of nanostructures allows for the controlled incorporation of materials available by synthetic routes. Biological macromolecules, nevertheless, offer superior polyfunctionality compared to synthetic macromolecules. We preferentially use them. 

Metalation of the amidine 87, followed by introduction of 2-methoxyallyl bromide, furnished the intermediate 88, which underwent acid-induced cyclization to the product 89 (Scheme 12), illustrating an interesting approach to polyfunctionalized indoles suitable for further elaboration <20020L1819>. 

The use of norbomene as a scaffold for aromatic C-H functionalization, a process we dubbed the Catellani Reaction, is a useful and mechanistically interesting method for the polyfunctionalization of aromatic molecules. Through the development and study of palladium complexes with norbomene, a powerful synthetic method has emerged which has been proven useful primarily through the research efforts of Catellani and Lautens. Future studies in this area should focus on expanding the already wide variety of products available, and to develop and/or utilize new reactions which can be performed on either the palladacycle intermediate or terminal arylpalladium(II) species. 

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