Alkene Linker Units

Linker Strategies in Solid-phase Organic Synthesis, Wiley, Chichester, UK, 2009. 611 pp. 

LINKER STRATEGIES IN MODERN SOLID-PHASE ORGANIC SYNTHESIS 

Dorwald, Organic Synthesis on Solid-phase. 2nd ed., Wiley-VCH, Weinheim, 1999. 530. pp. 

Mergler, R. Nyfeler, R. Tanner, J. Gosteli, P. Grogg, Tetrahedron Lett. 1988, 29, 4009. 

Barlos, D. Gatos, J. KaUitsis, G. Papaphotiu, P. Sotiriu, Y. Wenqing, W. Schafer, Tetrahedron Lett. 1989, 30, 3943. 

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With this aim, the group of Norrby developed a transition state force field for the study of the asymmetric dihydroxylation reaction [91]. This force field is purely developed from quantum mechanical reference data [92]. In their studies they use different ligands from the first generation (where the amine ligands are the alkaloids dihydroquine or dihydroquinidine) and second generation (where a symmetric linker couples two alkaloid units), and several alkenes. The calculated ee s are in very good agreement with experiment. 

CM has been reported to provide a synthetic tool for immobilization of reagents. Polymer-supported synthesis with an allylsilyl unit as a linker was developed. Divinylbenzene cross-linked allyldimethylsilylpolystyrene has been reported to undergo highly efficient ruthenium-catalyzed CM with functionalized terminal alkenes (Eq. 45) [78]. Products have been liberated by proto-desilylation with trifluoroacetic acid. 

Complex 33, containing a partially reduced 1,10-phenantroline-based monodentate NHC ligand led to 97% yield and 81% ee in the hydrogenation of methyl acetamidoacrylate (Figure 13.4). A bidentate NHC bearing a PPh2 unit with a chiral pseudo-o-[2.2]paracyclophane linker (34) was found to be a selective catalysts for non-functionalized trisubstituted alkenes, although functionalized alkenes were found to be sensitive to the H2 pressure. Also, the... 

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