Syringaldehyde resin

Wang Ratio resin Min Yield (%) HMPB-AM resin Ratio Min Yield (%) Syringaldehyde resin Ratio Min Yield (%) ... 

For the development of an appropriate strategy for cleavage from the novel syringaldehyde resin, the authors adapted a previously elaborated solution-phase model study on intramolecular Diels-Alder reactions for the solid-phase procedure (Scheme 7.60). The resulting pyridines could be easily separated from the polymer-bound by-products by employing a simple filtration step and subsequent evaporation of the solvent. The remaining resins were each washed and dried. After drying,... 

Utilizing the novel syringaldehyde resin, smooth release from the support could be achieved upon microwave heating of a suspension of the resin-bound pyridinones in trifluoroacetic acid/dichloromethane (5 95) at 120 °C for just 10 min. The very mild cleavage conditions for this new linker, as well as its stability towards various reaction conditions and its easy accessibility, make it highly suitable for ongoing pyrazinone chemistry. 

Wang resin HMPB-AM resin Syringaldehyde resin... 

For the solid-phase experiments [115], the commercially available Wang and HMPB-AM resins were chosen due their stability under the applied reaction conditions and an easy cleavage with TFA/DCM mixtures. Moreover, a novel, tailor-made and readily available linker, derived from inexpensive syringaldehyde was designed and proven to be superior to both standard Wang and HMPB-AM resins. For an initial study, as a proof of concept , the Wang linker was mimicked with a 4-methoxybenzyl group at N-1 position of a pyrazinone, and the sequence was evaluated in solution (Scheme 41). 

The novel linker was produced by cesium carbonate activated coupling of commercially available syringaldehyde to Merrifield resin, under microwave heating conditions. Subsequently, the aldehyde moiety was reduced at room temperature within 12 h and the benzylic position was finally brominated by treatment with a large excess of thionyl bromide (10 equiv) leading to the desired polymeric support (Scheme 7.44). 

Many phenolic compounds other than phenylpropanoids can be obtained from plants catechol, guaiacol, syringic acid, syringaldehyde, gallic acid, vanillin, and vanillic acid are obtained from plants. These phenolic compounds have become candidates for monomers used in the polymer industry. They undergo oxidative polymerization and serve as monomers for phenol-formaldehyde type resins, and some compounds having a hydroxyl group and a carboxylic acid serve as monomers for polycondensation. 

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