Total synthesis of clathculins A and B.

Clathculins A and B represent a new class of vic-diamine alkaloids containing a PA2 unit as the basic structure. We report the first total syntheses of 1 and 2, which confirm the assigned structure of each. Dependence of their NMR spectroscopic behavior as a function of protonation state has been observed.

The small molecule 2-furylacrylic acid inhibits auxin-mediated responses in Arabidopsis thaliana.

Auxins, typified by IAA, are a class of plant hormones involved in a wide array of processes including cell division, cell elongation, tissue patterning, phototropism, gravitropism and root development. Despite recent descriptions of the machinery involved in auxin transport and perception, additional regulatory mechanisms and components remain to be identified and characterized. Chemical genetics has proven to be a valuable means by which to investigate the auxin response pathway in Arabidopsis thaliana.

No-D NMR study of the pathway for n-BuLi "oxidation" of 1,5-cyclooctadiene to dilithium cyclooctatetraene dianion [Li2COT2-].

[Reaction: see text] The transformation of 1,5-cyclooctadiene (1) into cyclooctatetraene (3) by way of dianion 2 is an interesting reaction of considerable preparative value. The mechanism was initially suggested to involve lithium hydride loss from 4a/4b, followed by two deprotonations to produce 2. This No-D 1H NMR study indicates the long-term stability of 4a/4b (in the absence of additional n-BuLi) and suggests a different mechanistic sequence, in which 4a/4b is deprotonated a second time prior to LiH ejection.