Three nepetalactones were isolated from Nepeta racemosa (mussinii) by traditional methods. An improved method was developed to isolate nepetalactones from N. faassénii. An epimerization procedure was used to prepare the fourth 7S-nepetalactone diastereomer. The cis-fused nepetalactols were prepared by reduction of the corresponding nepetalactones, while the trans-fused nepetalactols were unstable and found to undergo ring-opening reactions yielding iridodials. The characterizations and structural assignments by means of NMR agree with quantum chemical density functional calculations.

Enantioselective Preparation of the Stereoisomers of 4-Methylheptan-3-ol Using Candida antarctica Lipase B.-The four stereoisomers of 4-methylheptan-3-ol (V), components of the aggregation pheromone of some bark beetles, are prepared through fractional crystallization of a mixture of their racemic dinitrobenzoates (III) and (IV), followed by hydrolysis and enantioselective, lipase-mediated transesterification.-(UNELIUS, C. R.; SANDELL, J.; ORRENIUS, C.; Collect.

The four stereoisomers of 4-methylheptan-3-ol were prepared through fractional crystallization of a mixture of their racemic 4-methylhept-3-yl 3,5-dinitrobenzoates, followed by hydrolysis of each crystalline racemate and enantioselective, lipase-mediated transesterification of each pair of enantiomeric alcohols liberated, using the Candida antarctica lipase B as catalyst and S-ethyl octanethioate as the acyl donor. An analytical method of determining the enantiomeric composition of mixtures of 4-methyl-heptan-3-ols was developed. The optical purity of the separated isomers was in the range of 29-97%.