Organocatalytic ester activation is developed for a highly selective cascade reaction between saturated esters and amino enones. The reaction involves activation of the β-carbon atom of the ester as a key step. This method allows a single-step access to multicyclic oxoquinoline-type heterocycles with high enantiomeric ratios.

Plants of the genus Taraxacum Wigg., have long been used as medicinal herbs. A phytochemical investigation of the aerial parts of Taraxacum bessarabicum (Hornem.) Hand.-Mazz. subsp. bessarabicum (Hornem.) Hand.-Mazz. (Asteraceae) yielded two coumarins [esculetin (1), cichoriin (2)], three flavonoids [ luteolin (3), luteolin 7-O-β-D-glucoside (4), gossypetin (5)] and six phenolic acids and their...

The functional determinants of the insulinotropic action of α-d-glucose pentaacetate were investigated in rat pancreatic islets. The ester mimicked the effect of nutrient secretagogues by recruiting individual B cells into an active secretory state, stimulating proinsulin biosynthesis, inhibiting86Rb outflow, and augmenting45Ca efflux from prelabeled islets. The secretory response to the ester ...

Heteroaromatic sulfinates are effective nucleophilic reagents in Pd0-catalyzed cross-coupling reactions with aryl halides. However, metal sulfinate salts can be challenging to purify, solubilize reaction media, and not tolerant multi-step transformations. Here we introduce base-activated, latent reagents: β-nitrile β-ester sulfones. We show that under the conditions, these species generate salt...

An effective synthesis for syn-β-lactams was achieved using a Rh-catalyzed reductive Mannich-type reaction. A rhodium-hydride complex (Rh-H) derived from diethylzinc (Et2Zn) and a Rh catalyst was used for the 1,4-reduction of an α,β-unsaturated ester to give a Reformatsky-type reagent, which in turn, reacted with an imine to give the syn-β-lactam. Additionally, the reaction was applied to the s...

An entomopathogenic fungus, Paecilomyces lilacinus, was found to grow on chitosanase-detecting plates. Besides an endo-chitosanase, an exo-β-D-glucosaminidase was purified by cation-exchange chromatography from this microorganism cultivated in M9 minimal media containing 0.5% chitosan as the sole carbon source. The molecular weight of the enzyme is 95kDa; the optimum pH and temperature for acti...

NAG-thiazoline is a strong competitive inhibitor of GH20 β-N-acetyl- hexosaminidases and GH84 β-N-acetylglucosaminidases. Here, we focused on the design, synthesis and inhibition potency of a series of new derivatives of NAG-thiazoline modified at the C-6 position. Dimerization of NAG-thiazoline via C-6 attached triazole linkers prepared by click chemistry was employed to make use of multivalen...

The study of the chemical constituents of the whole plant of Erigeron bonariensis (L.) has resulted in the isolation and characterization of a new and nine known compounds. The known compounds were identified as stigmasterol (1), freideline (2), 1,3-dihydroxy-3R,5R-dicaffeoyloxy cyclohexane carboxylic acid methyl ester (3), 1R,3R-dihydroxy4S,5R-dicaffeoyloxycyclohexane carboxylic acid methyl es...