Immobilized Catalysts

Over the last decade the environmental setup has changed for synthetic organ­ ic chemists to a considerable degree. So far synthetic organic chemistry had focussed on methodology development which mainly deals with the develop­ ment of new reactions as well as new reagents and catalysts. These ought to be able to perform preferentially highly selective (chemo-, regio-and stereose­ lective) synthetic transformations, often applied in the context of complex and highly functionalized molecules. Except for the synthesis of peptides and oligonucleic acids, little attention has been spent on the question of how synthesis can be carried out in an envi­ ronment of sophisticated technologies which includes improved hardware. While peptides and oligonucleotides are conveniently prepared by Merrifield's solid phase technique, solution phase synthesis of most other synthetic targets have not been substantially replaced by this solid phase approach. Without discussing this aspect in detail it is obvious that today a renaissance of sophis­ ticated solution phase synthesis can be noted. Immobilization of reagents and particularly catalysts, an old concept indeed, recently returned back onto the stage and this is addressed in this volume of Topics in Current Chemistry in a broader sense.