The aldol reaction of tetrahydro-4H-thiopyranone with 1,4-dioxa-8-thiaspiro[4.5]decane-6-carboxaldehyde (I) gives four possible diastereomeric adducts (II). Aldol reactions of I with each of the diastereomers of II and their corresponding methoxymethyl ethers III via the Ti enolates were investigated. Using racemic reactants, reactions with II proceeded with high levels of mutual kinetic enantioselection (MKE) and double stereodifferentiation (DS) to give one of the eight possible bisaldol adducts. Similar reactions of III proceeded with low levels of MKE and DS and gave two bisaldol adducts, one from each of the possible combinations of enantiomeric reactants. By extension, 11 of the 20 possible diastereomers of the bisaldol adduct could be obtained selectively. These adducts are useful for polypropionate synthesis.

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The plant hormone abscisic acid (ABA) plays many important roles in controlling plant development and physiology, from flowering to senescence. ABA is now known to exert its effects through a family of soluble ABA receptors, which in Arabidopsis thaliana has 13 members divided into three clades. Homologues of these receptors are present in other plants, also in relatively large numbers. Investigation of the roles of each homologue in mediating the diverse physiological roles of ABA is hampered by this genetic redundancy. We report herein the in vitro screening of a targeted ABA-like analogue library and identification of novel antagonist hits, including the analogue PBI686 that had been developed previously as a probe for identifying ABA-binding proteins. Further in vitro characterization of PBI686 and development of second-generation leads yielded both receptor-selective and universal antagonist hits. In planta assays in different species have demonstrated that these antagonist leads can overcome various ABA-induced physiological changes. While the general antagonists open up a hitherto unexplored avenue for controlling plant growth through inhibition of ABA-regulated physiological processes, the receptor-selective antagonist can be developed into chemical probes to explore the physiological roles of individual receptors.

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