ROMP-spheres

Scheme S.5 Synthesis of ROMP-spheres used for combinatorial chemistry.

ROMP-Spheres A Novel High-Loading Polymer Support Using Cross Metathesis between Vinyl Polystyrene and Norbor-nene Derivatives, A. G.M. Barrett,... 

Barrett AGM, Bibal B, Hopkins BT, Kdebberling J, Love AC, Tedesebi L. Facile and purification free synthesis of peptides utilizing ROMP gel- and ROMP sphere-supported coupling reagents. Tetrahedron 2005 61 12033-12041. 

An alternative to Merrifield resins, that is, the synthesis of ROMP spheres for use in combinatorial chemistry, was reported hy Barrett et Here, surface functionalization... 

Among the first 18-electron (18e) Fischer-type metal carbene complexes to be used as part of an olefin metathesis catalyst system were W[=C(OMe)Et](CO)5 with BU4NCI (for pent-l-ene)79, and W[=C(OEt)Bu](CO)5 with TiCLt (for cyclopentene)80. These complexes may also be activated thermally, e.g. for the polymerization of alkynes81, or photochemically, e.g. for the ROMP of cycloocta-1,5-diene82. The essential requirement is that a vacancy be created at the metal centre to allow the substrate to enter the coordination sphere. Occasionally the substrate may itself be able to displace one of the CO ligands. 

A variety of NHC-ruthenium catalysts exhibiting different coordination spheres were synthesized, for example Schiff base (see complex 28) [77], arene (see complex 29) [78], and metallic moieties (see complexes 30) [7,79, 80] (Fig. 5) and show activity in RCM and ROMP. 

By ROMP of norbornenyl-(PS-b-PEO) macromonomers, amphiphilic spheres with hydrophilic or hydrophobic outer layer have been synthesized. Scheme 5. The peculiar topology of these polymacromonomers makes them particularly suitable for applications such as unamolecular micelles or associative thickeners. 

Examination of the catalytic activity of the vinylidene complex 17 revealed this complex to be more active than 15, pointing out to a higher unsaturation in the coordination sphere of the metal. This characteristic behaviour of 17 has been evidenced in RCM of diethyl diallylmalonate, metathesis dimerization of allyl benzene, and ROMP of 1,5-cyclooctadiene (Scheme 11). 

Figure 3.10 Synthesis of glycopolymer via ROMP and its conjugation to ChSA using click chemistry. ChSA is represented by solid sphere in the scheme. Reproduced with permission from T. Lipinski, P.I. Kitov, A. Szpacenko, E. Paszkiewicz and D.R. Bimdle, Bioconjugate Chemistry, 2011,22, 274. 2011, American Chemical Society [27]...

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