Optical activity Neolignans

Katayama T, Kado Y (1998) Formation of optically active neolignans from achiral coniferyl alcohol by ceU-free extracts of Eucommia idmoides. J Wood Sci 44 244-246... 

Neolignans are also compounds composed of two phenylpropanoid units, but linked in a manner other than C8-C8 (Fig. 12.1) [10]. The compounds of this class are often chiral and naturally occurring neolignans are usually optically active, which evokes the involvement of DPs in the biosynthesis of neolignans. 

A crude enzyme preparation from Vinca rosea catalyzed the enantioselective coupling of coniferyl alcohol to give rise to an optically active C8-C5 neolignan, dehydrodiconiferyl alcohol, with a ratio of (—)-enantiomer to (+)-enantiomer of 2 1 (Fig. 12.10) [66],... 

Incubation of coniferyl alcohol with a crude enzyme preparation from Eucommia ulmoides in the presence of hydrogen peroxide resulted in optically active C8-0-C4 neolignan dimers, (+)-eryf/rro-guaiacylglycerol-( >-coniferyl ether (38% e.e.), and (-)-t/ire<9-guaiacylglycerol- 3-coniferyl ether (34% e.e.) (Fig. 12.11) [68]. In... 

The term lignan typically refers to dimers of monolignols that are linked via an 8-8 (P-P ) bond, whereas the term neolignan refers to dimers and oligomers that contain bonds other than the 8-8 bond. Most lignans are optically active, and typically only one enantiomer is found in a given species. Examples of lignans include (+)-pinoresinol (1.72), (+)-sesamin (1.73), and (-)-plicatic acid (1.74). 

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