Argogel™ polymer

In Scheme 51, an example for the immobilization of the germanium-based precursor 100 to Argogel polymer is shown208. The clean release of several biaryl compounds from the polymer 101 was achieved by electrophilic degermylation with various reagents (i-iv) (Scheme 51). 

Hallman and Moberg described the preparation of a chiral bis(oxazoline) grafted on ArgoGel [120] (87, in Scheme 48). In the zinc-catalyzed Diels-Alder reaction, polymer 87 was found to be less active than the analogous... 

In another example, a polymer-supported chromium porphyrin complex was supported on ArgoGel Cl and then employed for the ring-opening polymerization of 1,2-cyclohexene oxide and C02 [95], This complex showed higher activity than a C02-soluble equivalent, and the solid nature of the catalyst meant that recycling of the catalyst was much easier. 

Cyclization of the bisurethane 198 to the oxazolidin-2-one 199 was examined by using the polymeric catalyst derived from 197 (Scheme 3.64), which was prepared by using ArgoGel-NH2 as the polymer support. Altliough a somewhat lower enantioselectivity was obtained with the non-supported catalyst than with the supported catalyst, the former could be recycled several times without any significant differences in either yield or enantiomeric excess [127]. 

Scheme 54). This supported catalyst was formed by grafting a phenolic bis(oxazoline) derivative onto an ArgoGel Wang-Cl resin and presented 0.071 mmol of ligand/g polymer. 

Merrifield resin, polystyrene matrix, Argogel matrix Figure 31.7 Polymer-supported Fischer carbene chromium complexes. 

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