Polymer-supported protective groups, reviews

E. C. Blossey and D. C. Neckers, Eds., Solid Phase Synthesis, Halsted, New York, 1975 P. Hodge and D. C. Sherrington, Eds., Polymer-Supported Reactions in Organic Synthesis, Wiley-Interscience, New York, 1980. A comprehensive review of polymeric protective groups by J. M. J. Frechet is included in this book. 

The present chapter will review the current state-of-the-art regarding the use of polymers as supports for catalysts and related systems. The variety of applications where polymer supports have proved invaluable has expanded enormously in the last decade or so, and to review comprehensively even the limited area of polymer-supported reagents, catalysts and protected groups [1] would be a major undertaking. This chapter will not therefore attempt to do so, but instead will refer to the many excellent books and reviews on this subject, and then describe some more recent works which exemplify the strategically important developments that are currently underway. 

A wide variety of reagents, catalysts, protecting groups, auxiliaries, etc. have been immobilised on polymer supports (Figure 6.1). The literature has been reviewed fairly comprehensively up to 1988 [18], but thereafter the number of papers appearing has escalated so that full coverage has become difficult. One particularly useful summary appeared in 1981 [70] with an up-date in 1983 [71], and the value of this lay in the convenient tabulation of the polymer structures which had been explored, and the reactions in which the supported species had been exploited. 

Polymers as Supports and Protecting Groups,—Although almost all of the early work involving polymer supports was concentrated on repetitive sequential syntheses such as those of polypeptides, nucleosides, and polysaccharides, many other applications have now been devised and have led to a better understanding of both the advantages and limitations of polymer-supported species. There have been a number of reviews. ... 

While PEG-based supports are widely used for liquid-phase combinatorial chemistry, other non-PEG-based soluble polymers have also been reported for combinatorial applications. A recent review (276) contains an exhaustive list of homo- and copolym-eric soluble supports used in peptide, oligonucleotide, and oligosaccharide synthesis, including combinatorial chemistry. Two of these supports have also been used for small organic molecule synthesis. Homopolymeric polyvinyl alcohol was used in conjunction with PEG for a protection/derivatization strategy in solution (284), and the copolymer between isopropylacrylamide and acrylic acid was used in the catalytic hydrogenation of a Cbz group (285). 

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