Cinnamyl alcohols polymerization

In order to avoid polymerization and to achieve better stereocontrol by quasi-intramolecular addition, a carbanion-stabilizing group and a complexing substituent for capturing alkyllithium/(—)-sparteine in the substrate are useful. This carbolithiation protocol was realized with great success by Marek, Normant and coworkers (equation 125) Addition of n-BuLi/(—)-sparteine (11) onto the lithium alcoholate derived from ( )-cinnamyl alcohol (457) in cumene at 0°C afforded the addition product with 82% yield and 80% ee. 

It has been reported that reaction of n. 3-unsatu rated carboxylic acids with bis(collidine)bromine(l) hexafluorophos-phate leads to the formation of 2-oxetanones in moderate yields (Equation 33) <1999JOC81>. As with the related reaction of cinnamyl alcohols (discussed in Section 2.05.9.1), this 4- electrophilic intermediate. The cyclization reaction was diastereospecific single (E)- or (Z)-isomers were reacted to give single stereoisomeric products. Lactonization was favored by substrates that were /3-dialkyl-substituted, or ct-alkyl/aryl-, /3-aryl-substituted on the C-C double bond. ct-Monoalkyl/aryl, /3-unsubstituted substrates gave either polymeric products or exclusive vinyl bromide formation. 

Lignin Complex molecules that constitute part of the insoluble dietary fiber. It is formed from cinnamyl alcohols that form the phenylpropaue units by a complex polymerization process. Lignin is viewed as a three-dimensional molecule formed by the aromatic hydroxyphenyl, guaiacyl, and springyl moieties. It is the main structural component of plant tissues. It is highly resistant to enzymes and chemical degradation. 

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