Syringaldehyde

Syringaldehyde is easily methylated or ethylated with the known procedures in high yields forming the highly-desirable 3,4,5-trimethoxybenzaldehyde or the 3,5-di-MeO-4-EtO-benzaldehyde (Escaline, 72, 40-60 mg, 8-12 hrs.). 

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). 

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

The total phenolic content in XRPP was 1.10%. The major components were found to be p-hydroxybenzoic acid (0.44%), vanillin (0.19%), syringic acid (0.13%), and syringaldehyde (0.13%). The contents of p-hydroybenzaldehyde, vanillic acid and ferulic acid were 0.032, 0.015 and 0.020%, respectively. Gallic acid, protocatechuic acid and cinnamic acid were detected in trace amounts. 

Experimental Procedure19 for 4-bis(4-dimethylaminophenyl)methyl-2,6 dimethoxyphenol (55a). A mixture of syringaldehyde (5.46 g, 30 mmol, A.A-dimethylaniline (7.26 g, 60 mmol), urea (2.7 g), and concentrated sulfur ic acid (4.41 g) in isopropanol (100ml) was heated at 90°C under a nitrogen atmosphere for 24h. The reaction was cooled to room temperature and 40ml of water added followed by 50% NaOH until alkaline. The mixture was filtered and the residue washed with 200ml of cold water. The solid was recrystallized from ethanol and yielded 12.0g (97%), mp 136-138°C. 

Sulfuric acid, fuming, 31, 23, 45 Sulfuryl chloride, 33, 45 Syringaldehyde, 31, 92... 

Treatment of suberin with nitrobenzene generates vanillin, p-hydroxy benz-aldehyde, but not much syringaldehyde that arises mostly from lignin. 

Reported redox potentials of laccases are lower than those of non-phenolic compounds, and therefore these enzymes cannot oxidize such substances [7]. However, it has been shown that in the presence of small molecules capable to act as electron transfer mediators, laccases are also able to oxidize non-phenolic structures [68, 69]. As part of their metabolism, WRF can produce several metabolites that play this role of laccase mediators. They include compounds such as /V-hvdi oxvacetan i I ide (NHA), /V-(4-cyanophenyl)acetohydroxamic acid (NCPA), 3-hydroxyanthranilate, syringaldehyde, 2,2 -azino-bis(3-ethylben-zothiazoline-6-sulfonic acid) (ABTS), 2,6-dimethoxyphenol (DMP), violuric acid, 1-hydroxybenzotriazole (HBT), 2,2,6,6-tetramethylpipperidin-iV-oxide radical and acetovanillone, and by expanding the range of compounds that can be oxidized, their presence enhances the degradation of pollutants [3]. 

For this approach a novel, tailor-made and readily available linker, derived from inexpensive syringaldehyde, was developed [69]. This novel linker was produced by... 

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. 

To correlate these changes in absorption with theory, the ultraviolet spectroscopic behavior of model compounds closely related to the degradation products isolated from bagasse native lignin, i.e., p-hydr-oxybenzaldehyde, vanillin and syringaldehyde, was determined. The compounds used were p-hydroxypropiophenone, vanillin, acetovanillone and acetosyringone and their derivatives. 

Benzoic aldehydes mainly cover syringaldehyde and vanillin. Natural vanilla is prepared from the seeds (beans) of Vanilla planifolia, which may contain about 21 mg/ 100 g FW total phenols, including the major components vanillin (19.4 mg/100 g FW), 4-hydroxybenzaldehyde (1 mg/100 g FW), and vanillic acid (0.4 mg/100 g FW) (Clifford 2000b). In mango, vanillin has been found as free as well as vanillyl glu-coside (Sakho and others 1997). It has also been found in lychees (Ong and Acree 1998) and wines (Moreno and others 2007). For analysis of both brandy and wine aged in oak barrels, the limits of detection were found to be 27.5, 14.25, 14.75, and... 

Benzoic aldehydes Syringaldehyde Ripe walnut fruit... 

Colaric M, Veberic R, Solar A, Hudina M and Stampar F. 2005. Phenolic acids, syringaldehyde, and juglone in fruits of different cultivars of Juglans regia L. J Agric Food Chem 53(16) 6390-6396. 

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