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The relative stabilities of several cis- and trans-hydrindanones were compared using both isomerization experiments and MM2 calculations. The generally believed rule that cis-hydrindanones are more stable than trans-isomers is applicable, but is not always true. This review introduces examples, mainly from studies in our laboratory, to explain these facts.

One-electron reductive intramolecular cyclization of enones with ketones or aldehydes mediated by samarium diiodide and electrolysis to afford cis-trimethyl- hydrindanolones. The reactions gave selectivities ranging from 1:1 to 100:0 depending on the conditions.

Two samples of Cremanthodium stenactinium (Asteraceae) were collected in Sichuan Province, China. From the ethyl acetate extracts of the roots, three new eremophilane-type sesquiterpenoids and one new trinoreremophilane compound were isolated, together with other known eremophilanes. Their structures were determined based on the spectroscopic data. This is the first report of isolation of eremophilane-type compounds from the genus Cremanthodium.

Medium sized carbocycles are particularly difficult to synthesize. Ring closing metathesis reactions (RCM) have recently been applied to construct eight-membered carbocycles, but trisubstituted double bonds in the eight-membered rings are more difficult to produce using RCM reactions. In this review, model examples and our own results are cited and the importance of the preparation of suitably designed precursors is discussed. Examples of RCM reactions used in the total synthesis of natural products are also outlined.

Allylic alcohols were isomerized into ketones by the action of the Grubbs reagent. Some model alcohols were prepared and tested under similar conditions to reveal that less substituted alkenes rearrange more easily. More hindered alcohols are stable under these conditions, however, the simple allylic alcohols tend to isomerize producing ethyl ketone and the corresponding degraded methyl ketone.

(12E,14E,17E)-11-Hydroxy-12,14,17-dodecatrienoic acid was isolated from the stems of Ilex integra and its structure was determined on the basis of the spectroscopic data of its methyl ester.

The title compounds have been synthesized starting from l-menthone by application of a ring-closing metathesis reaction to confirm their reported absolute and relative stereochemistry. Comparisons of the NMR spectra and specific rotations are also discussed.

The diversity in root chemicals and evolutionally neutral DNA regions in the complex of Ligularia duciformis, L. kongkalingensis, and L. nelumbifolia (the d/k/n complex) was studied using eight samples collected in central and northern Sichuan Province of China. Cacalol (14) and epicacalone (15), rearranged eremophilanes, were isolated from the complex for the first time. Two new phenylpropanoids were also obtained. Seven of the eight samples produced phenylpropanoids and the other produced lupeol alone. Two of the seven samples also produced furanoeremophilanes or their derivatives and one produced oplopanes. The geographical distribution of the sesquiterpene-producing populations suggests that the production of sesquiterpenes evolved independently in separate regions. L. limprichtii collected in northern Sichuan was also analyzed and its chemical composition and the sequence of internal transcribed spacers (ITSs) in the ribosomal RNA gene cluster were found to be similar to that in the d/k/n complex and L. yunnanensis, which are morphologically similar.