Nomenclature and Structure-Activity Relationships

In older literature, a cydopentane-based nomenclature was often used, where, the side-chains were located at C-1 and C-2, and the carbonyl carbon atom was assigned the number 3. From time to time, the absolute configuration at C-1 was wrongly denoted as (S). Newer literature treats jasmonates as derivatives of fatty acids, and numbers the carbon atoms accordingly. The correct absolute configuration ofthe most stable methyl jasmonate is (3R,7R). [79] 

The primary product of biosynthesis is the (3R,7S)-jasmonate. The thermodynamic equilibrium lies at 7 93 in favour of the trans isomers, which results very easily from keto-enol tautomerism. It is not clear whether epimerisation takes already place in the plant or first occurs duringthe extraction process. The four diastereomers of methyl (Z)-jasmonate can be separated by preparative HPLC. 

Remarkably, only the (3R)-diastereomers are scented they are described by the perfumer as floral, jasmine-like, and mildly friiity. Both of the other diastereomers are almost odourless. The scent thresholds of the (3R,7S)- and (3R,7R) diastereomers differ fi om each other by a factor of approximately 20 (Fig. 3.22). [80] 

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