Exploring geography and evolutionary history as drivers of variation in floral scent chemistry in western sessile-flowered Trillium using parsimony-constrained phylogenetics.

Background And Aims: The sessile-flowered Trillium species from western North America have been challenging to distinguish morphologically owing to overlapping characters and intraspecific variation. Molecular phylogenetic analyses, currently inconclusive for this group, have not sampled multiple populations of the different species to account for this. Here, we query the diversity of floral volatile composition to understand its bearings on the taxonomy, distribution and evolution of this group.

Taxonomic insights from floral scents of western North American sessile-flowered Trillium.

Premise: Chemical composition of floral volatiles can be an important complement to morphological characters in describing and identifying species. Four of the five species of western sessile-flowered Trillium are challenging to distinguish morphologically due to wide intraspecific variation and overlapping characters among taxa. Characterizing their floral volatile compositions could aid future taxonomic, ecological, and evolutionary studies of Trillium and related taxa.

Chemotaxonomy of Pseudowintera: sesquiterpene dialdehyde variants are species markers.

Two sesquiterpene dialdehydes, the 1beta-E-coumaroyl-5alpha-hydroxypolygodial plus the known 1beta-E-cinnamoyl-5alpha-hydroxypolygodial, were isolated from the recently described species Pseudowintera insperata. This discovery is a further example of the rare sesquiterpene dialdehyde coumarate/cinnamate combination being found exclusively in the family Winteraceae. Another sesquiterpene dialdehyde, isopaxidal, with the rare rearranged drimane skeleton, was isolated from Pseudowintera axillaris.

O-nucleophilic amino alcohol acyl-transfer catalysts: the effect of acidity of the hydroxyl group on the activity of the catalyst.

[reaction: see text]. Amino alcohol-derived acyl-transfer catalysts are shown to operate by an O-nucleophilic mechanism, and catalysts bearing electron-withdrawing groups in proximity to the hydroxyl group are found to be more active. This is attributed to an increase in the acidity of the hydroxyl group of the catalyst.