Nickel-Catalyzed Chemo-, Regio- and Diastereoselective Bond Formation through Proximal C-C Cleavage of Benzocyclobutenones.

The first catalytic intermolecular proximal C1-C2 cleavage of benzocyclobutenones (BCB) without prior carbonyl activation or employing noble metals has been developed. This protocol operates at room temperature and is characterized by an exquisite chemo-, regio- and diastereoselectivity profile, constituting a unique platform for preparing an array of elusive carbocyclic skeletons.

Chemical genetics reveals cross-activation of plant developmental signaling by the immune peptide-receptor pathway.

Cells sense and integrate multiple signals to coordinate development and defence. A receptor-kinase signaling pathway for plant stomatal development shares components with the immunity pathway. The mechanism ensuring their signal specificities remains unclear. Using chemical genetics, here we report the identification of a small molecule, kC9, that triggers excessive stomatal differentiation by inhibiting the canonical ERECTA receptor-kinase pathway. kC9 binds to and inhibits the downstream MAP kinase MPK6, perturbing its substrate interaction. Strikingly, activation of immune signaling by a bacterial flagellin peptide nullified kC9's effects on stomatal development. This cross-activation of stomatal development by immune signaling depends on the immune receptor FLS2 and occurs even in the absence of kC9 if the ERECTA-family receptor population becomes suboptimal. Furthermore, proliferating stomatal-lineage cells are vulnerable to the immune signal penetration. Our findings suggest that the signal specificity between development and immunity can be ensured by MAP Kinase homeostasis reflecting the availability of upstream receptors, thereby providing a novel view on signal specificity.

Mechanisms and kinetics for sorption of CO2 on bicontinuous mesoporous silica modified with n-propylamine.

We studied equilibrium adsorption and uptake kinetics and identified molecular species that formed during sorption of carbon dioxide on amine-modified silica. Bicontinuous silicas (AMS-6 and MCM-48) were postsynthetically modified with (3-aminopropyl)triethoxysilane or (3-aminopropyl)methyldiethoxysilane, and amine-modified AMS-6 adsorbed more CO(2) than did amine-modified MCM-48. By in situ FTIR spectroscopy, we showed that the amine groups reacted with CO(2) and formed ammonium carbamate ion pairs as well as carbamic acids under both dry and moist conditions. The carbamic acid was stabilized by hydrogen bonds, and ammonium carbamate ion pairs formed preferably on sorbents with high densities of amine groups. Under dry conditions, silylpropylcarbamate formed, slowly, by condensing carbamic acid and silanol groups. The ratio of ammonium carbamate ion pairs to silylpropylcarbamate was higher for samples with high amine contents than samples with low amine contents. Bicarbonates or carbonates did not form under dry or moist conditions. The uptake of CO(2) was enhanced in the presence of water, which was rationalized by the observed release of additional amine groups under these conditions and related formation of ammonium carbamate ion pairs. Distinct evidence for a fourth and irreversibly formed moiety was observed under sorption of CO(2) under dry conditions. Significant amounts of physisorbed, linear CO(2) were detected at relatively high partial pressures of CO(2), such that they could adsorb only after the reactive amine groups were consumed.

Discovery of synthetic small molecules that enhance the number of stomata: C-H functionalization chemistry for plant biology.

The increasing climate changes and global warming are leading to colossal agricultural problems such as abatement of food production and quality. As stomatal development is considered to play a key role in crop plant productivity and water-use efficiency, studying stomatal development is useful for understanding the productivity of plant systems for both natural and agricultural systems. Herein, we report the first-in-class synthetic small molecules enhancing the number of stomata in Arabidopsis thaliana that have been discovered by screening of the chemical library and further optimized by the Pd-catalyzed C-H arylation reaction. The present study shows not only huge potential of small molecules to control the cellular and developmental processes of stomata without using genetically modified plants, but also the power of C-H functionalization chemistry to rapidly identify the optimized compounds.

Manganese-catalyzed intermolecular C-H/C-H coupling of carbonyls and heteroarenes.

Manganese-catalyzed intermolecular C-H/C-H coupling of carbonyls and heteroarenes has been developed. The presence of NaIO4 as an oxidant is crucial for the catalytic reaction. These new, inexpensive reaction conditions allow the gram-scale synthesis of α-heteroaryl carboxylic acids.

Formal γ-alkynylation of ketones via Pd-catalyzed C-C cleavage.

A formal γ-alkynylation of ketones via Pd-catalyzed C-C bond-cleavage is presented. The method allows for the coupling of tert-cyclobutanols and bromoacetylenes, giving access to versatile alkynes that are beyond reach otherwise.

Ligand-accelerated Pd-catalyzed ketone γ-arylation via C-C cleavage with aryl chlorides.

A highly efficient Pd-catalyzed arylative ring expansion of cyclobutanols via C-C bond cleavage is presented. The method allows the coupling of aryl chlorides at low catalyst loadings with a wide range of functional groups and substitution patterns, thus constituting a straightforward alternative for preparing rather elusive γ-arylated ketones.

Microwave-assisted palladium-catalyzed cross-coupling of aryl and vinyl halides with H-phosphonate diesters.

A general and efficient method for the microwave-assisted formation of the C-P bond was developed. Using a prevalent palladium catalyst, Pd(PPh3)4, a quantitative cross-coupling of various H-phosphonate diesters with aryl and vinyl halides was achieved in less than 10 min. The reactions occurred with retention of configuration at the phosphorus center and in the vinyl moiety. Using this protocol, several C-phosphonates, including those bearing nucleoside and cholesteryl moieties, were prepared in high yields.