Eight avenanthramides, amides of anthranilic acid (1) and 5-hydroxyanthranilic acid (2), respectively, and the four cinnamic acids p-coumaric (p), caffeic (c), ferulic (f), and sinapic (s) acid, were synthesized for identification in oat extracts and for structure-antioxidant activity studies. Three compounds (2p, 2c, and 2f) were found in oat extracts. As assessed by the reactivity toward 1,1-diphenyl-2-picrylhydrazyl (DPPH), all avenanthramides except 1p showed activity. Initially, the antioxidant activity of the avenanthramides decreased in a similar order as for the corresponding cinnamic acids, that is: sinapic > caffeic > ferulic > p-coumaric acid. The avenanthramides derived from 2 were usually slightly more active than those derived from 1. All avenanthramides inhibited azo-initiated peroxidation of linoleic acid. 1c and 1s were initially the most effective compounds. The relative order of antioxidant activities was slightly different for the DPPH and the linoleic acid assays run in methanol and chlorobenzene, respectively.

The diastereoselectivity in intramolecular oxymercurations of γ-hydroxyalkenes bearing a remote allylic oxy substituent has been investigated. It was found that the best selectivity was obtained by employing a combination of (Z)-alkene geometry and a tert-butyldiphenylsilyl protecting group attached to the remote allylic oxygen as in 4a−g. Cyclization, using mercuric acetate in dichloromethane, of all the (Z)-alkenols gave the syn diastereomer, 5a−g, as the major product. For example, cyclization of 4b gave syn diastereomer 5b and anti diastereomer 6b in a ratio of 7:1. It was found that this ratio could be improved by replacing dichloromethane with acetonitrile. Under these conditions the ratio of 5b to 6b increased to 19:1. Cyclization of (E)-alkene 9 gave very poor diastereoselection. These syn-selective intramolecular oxymercurations were exploited in enantioselective syntheses of two diastereomers of methyl nonactate.

Pine weevils (Hylobius abietis) fed less on bark of lodgepole pine (Pinus contorta) than on bark of Scots pine (P. sylvestris). Two pine weevil antifeedants, ethyl trans-cinnamate and ethyl 2,3-dibromo-3-phenyl-propanoate, were isolated from bark of lodgepole pine. These two compounds significantly reduced pine weevil feeding in a laboratory bioassay. In field assays, the second compound significantly decreased pine weevil damage on planted seedlings. Ethyl 2,3-dibromo-3-phenylpropanoate has not previously been reported as a natural product.

Syntheses of the metabolites from platyphylloside, a phenol causing digestibility inhibition in rumen fluid, have been performed to identify the active metabolite. 1,7-Bis(4'-hydroxyphenyl)-3-heptanone (3-platyphyllone), racemic, and the two enantiomers of 1,7-bis(4'-hydroxyphenyl)-3-heptanol (centrolobol) and 1,7-bis(4-hydroxyphenyl)heptane (platyphyllane) were synthesized and tested regarding digestibility inhibition in vitro in cow rumen fluid. All compounds tested induced a decreased digestion. Centrolobol was found to be the metabolite causing the observed effect, and (R)-centrolobol was found to be the enantiomer formed in the rumen liquor in vitro.