Application of polymer-bound phosphonium salts as traceless supports for solid phase synthesis

Hughes, Ian

doi:10.1016/0040-4039(96)01669-3

Cited by 120 publications

(48 citation statements)

References 11 publications

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“…[261] Piscopio et al described the synthesis of Freidinger lactams 84 by using an initial Mitsunobu loading step to obtain an intermediate resin-bound sulfonamide 81 (Scheme 57). In this way, cyclic ketones, [327] tetramic acid derivatives, [328±331] indols (through the Wittig reaction), [332] and macrocycles (through the Horner ± Wadsworth ± Emmons reaction) have been prepared. The ring-closing step can also include formation of a bond between the carbon atoms of a nucleophilic and an electrophilic.…”

Section: Cyclative Cleavage With Formation Of a Càc Bondmentioning

confidence: 99%

Modern Separation Techniques for the Efficient Workup in Organic Synthesis

Tzschucke

Märkert

Bannwarth

et al. 2002

Angew. Chem. Int. Ed.

339

133

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The shift of paradigm in combinatorial chemistry, from large compound libraries (of mixtures) on a small scale towards defined compound libraries where each compound is prepared in an individual well, has stimulated the search for alternative separation approaches. The key to a rapid and efficient synthesis is not only the parallel arrangement of reactions, but simple work-up procedures so as to circumvent time-consuming and laborious purification steps. During the initial development stages of combinatorial synthesis it was believed that rational synthesis of individual compounds could only be achieved by solid-phase strategies. However, there are a number of problems in solid-phase chemistry: most notably there is the need for a suitable linker unit, the limitation of the reaction conditions to certain solvents and reagents, and the heterogeneous reaction conditions. Further disadvantages are: the moderate loading capacities of the polymeric support and the limited stability of the solid support. In the last few years several new separation techniques have been developed. Depending on the chemical problem or the class of compounds to be prepared, one can choose from a whole array of different approaches. Most of these modern separation approaches rely on solution-phase chemistry, even though some of them use solid-phase resins as tools (for example, as scavengers). Several of these separation techniques are based on liquid-liquid phase separation, including ionic liquids, fluorous phases, and supercritical solvents. Besides being benign with respect to their environmental aspects, they also show a number of advantages with respect to the work-up procedures of organic reactions as well as simplicity in the isolation of products. Another set of separation strategies involves polymeric supports (for example, as scavengers or for cyclative cleavage), either as solid phases or as soluble polymeric supports. In contrast to solid-phase resins, soluble polymeric supports allow reactions to be performed under homogeneous conditions, which can be an important factor in catalysis. At the same time, a whole set of techniques has been developed for the separation of these soluble polymeric supports from small target molecules. Finally, miscellaneous separation techniques, such as phase-switchable tags for precipitation by chemical modification or magnetic beads, can accelerate the separation of compounds in a parallel format.

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Section: Cyclative Cleavage With Formation Of a Càc Bondmentioning

confidence: 99%

Modern Separation Techniques for the Efficient Workup in Organic Synthesis

Tzschucke

Märkert

Bannwarth

et al. 2002

Angew. Chem. Int. Ed.

339

133

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“…[15] Tin-based linker (Nicolaou): Tin hydride reagents are versatile tools for the functionalization of alkenes and alkynes. However, this bond can also be cleaved by the aid of a base in absence of an aldehyde.…”

Section: Phosphorous-based Linker (Hughes)mentioning

confidence: 99%

Traceless Linkers-Only Disappearing Links in Solid-Phase Organic Synthesis?

Bräse

Dahmen

2000

Chem. Eur. J.

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Traceless linkers, which enable the attachment of arenes and alkanes to a polymeric support, have received increased attention in recent years. These anchoring groups allow chemical transformations on the polymer-bound molecules, which can be cleaved from the resin leaving no residual functionality to bias the library. Various approaches based on different Group 14 to Group 16 heteroatoms have been developed in the past and used in new syntheses of diverse compound libraries.

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“…For example, Hughes described the application of the solid-supported phosphonium salt 108. [67] Generated from the commercially available polystyrene-bound analogue of triphenylphosphane 107, it was then reduced to the aniline and further functionalised to give 109. Traceless cleavage was achieved with sodium methoxide in methanol to release the tolyl derivative 110.…”

Section: Diversity Through An Electrophilic Componentmentioning

confidence: 99%

Diversity Linker Units for Solid‐Phase Organic Synthesis

Scott

Steel

2006

Eur J Org Chem

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In recent years an ever‐increasing number of traditional solution‐phase reactions have been adapted for solid‐phase organic synthesis (SPOS) because of the ease of application of solid‐phase techniques to combinatorial chemistry and high‐throughput screening. To accommodate the growing number of reactions being attempted on solid supports, new linker units continue to be reported in the literature. Linker units are typically grouped according to the functionality left at the “cleavage site” in the target molecule, and are normally classified as traditional (polar functionality remains following cleavage) or traceless (hydrogen residue left after cleavage) linkers. As the field continues to expand, however, more advanced linker units have been reported, which utilise the cleavage step in SPOS to incorporate additional diversity into target libraries. These linker units have been termed “diversity” or “multifunctional” linker units, and in this microreview we introduce this aspect of the field, giving representative examples indicating key stages of development including the linker units recently designed in our laboratory. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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Application of polymer-bound phosphonium salts as traceless supports for solid phase synthesis

Cited by 120 publications

References 11 publications

Modern Separation Techniques for the Efficient Workup in Organic Synthesis

Modern Separation Techniques for the Efficient Workup in Organic Synthesis

Traceless Linkers-Only Disappearing Links in Solid-Phase Organic Synthesis?

Diversity Linker Units for Solid‐Phase Organic Synthesis

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