Sinapyl alcohol derivatives

Coniferyl and sinapyl alcohol derivatives Ligularia duciformis SiOj B + Me2CO B + AcOEt UV 254 nm H2SO4 + temperature Identification 74... 

In normal softwood lignin, usually referred to as guaiacyl lignin, the structural elements are derived principally from coniferyl alcohol, (1) (more than 95% of the total number of structural units), with the remainder consisting mainly of p-coumaryl alcohol-type units (Fig. 1.1, unit 2) and trace amounts of sinapyl alcohol-derived units (Fig. 1.1, unit 13). 

Whilst it is not possible to give a completely detailed structure for lignin, a great deal is known about the molecule. All lignins appear to be polymers of 4-hydroxycinnamyl alcohol (/>-coumaryl alcohol) or its 3- and/or 3,5-methoxylated derivatives, respectively coniferyl and sinapyl alcohol (Figure 3.1). 

Lignin has a complex structure that varies with the source, growing conditions, etc. This complex and varied structure is typical of many plant-derived macromolecules. Lignin is generally considered as being formed from three different phenylpropanoid alcohols— coniferyl, coumaryl, and sinapyl alcohols, which are synthesized from phenylalanine via various cinnamic acid derivatives and commercially is sometimes treated as being composed of a Cg repeat unit where the superstructure contains aromatic and aliphatic alcohols and ethers, and aliphatic aldehydes and vinyl units. 

The second type of data is derived from biochemical experiments related to the three cinnamyl alcohols—/>-coumaryl alcohol (I), coniferyl alcohol (II), and sinapyl alcohol (III) and their phenolic glucosides— >-glucocoumaryl alcohol (IV), coniferin (V), and syringin (VI). These and the following formulas do not differentiate between cis and trans isomers. 

The syringyl unit, derived from the frans-sinapyl alcohol, which is present with the guaiacyl unit in hardwoods... 

Cycloaddition of orf/io-quinone 162 with ferf-butyldimethylsilyl ether of sinapyl alcohol (163) yielded the 1,4-dioxane-linked adduct 164, as shown in Scheme 10b, but no regioisomer was detected. The ketal group in 164 was removed under acidic conditions and the derived ketone, a trans-cis mixmre in the ratio of 2 1, on treatment with alkali, yielded the frans-isomer, 165, in a good yield. The ketone 165 was converted to the key intermediate aldehyde 166 through the iodoform reaction, esterification, LAH reduction, and oxidation with Dess-Martin periodinane after protection of the hydroxy groups by MOM groups (Scheme 10b). 

The alcohols formed from some cinnamic acid derivatives, namely /7-coumaryl alcohol, coniferyl alcohol (LI), and sinapyl alcohol (L2), commonly known as monolignols, undergo dimerization reactions that yield lignans such as (-l-)-pinoresinol (L3), (-l-)-sesamin (L4), (-)-matairesinol (L5), and podophyllotoxin (L6) (Fig. 13). Several thousand lignans are found to occur in nature. Lignins, the structural components of plant cell walls, are polymers of monolignols and/or lignans. 

Similarly, the change in resinols C from being almost entirely derived from sinapyl alcohol in the wild-type to being derived from all three monomers, and p-coumaryl alcohol in particular, in the transgenic plants, is striking. It is logical that sinapyl alcohol monomers find themselves only rarely able to dimerize (with other sinapyl alcohol monomers) in this sinapyl-alcohol-depleted plant, so presumably P-P-cross-couple with coniferyl, and possibly p-coumaryl alcohol studies are... 

Traditionally, the organic components of expander formulations are derived from natural products such as wood pulp. The composition of such materials is poorly defined. Lignin extracts, frequently obtained from waste sulfite liquors in the papermaking industry, are purified by removing sugars and various metals, and then depolymerized to different degrees. Lignin molecules are formed from three primary precursors, p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol the... 

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