Total Synthesis of the Naturally Occurring Glycosylflavone Aciculatin.

The new flavone-glycoside aciculatin (1), from Chrysopogon aciculatus, has been shown to have cytotoxic, anti-inflammatory, and antiarthritis activity. Further biological studies have been limited because of the limited availability of 1 from natural sources. Herein the first total synthesis of 1 in an overall yield of 8.3% is described. The synthesis involved the regio- and stereoselective glycosylation-Fries-type O-to-C rearrangement to construct the C-aryl glycosidic linkage, followed by a Baker-Venkataraman rearrangement and cyclodehydration to form the flavone scaffold.

Discovery of tetrasubstituted thiophenes as Cisd2 activators: A potential novel therapeutic option in nonalcoholic fatty liver disease.

Down-regulation of Cisd2 in the liver has been implicated in the development of nonalcoholic fatty liver disease (NAFLD) and increasing the level of Cisd2 is therefore a potential therapeutic approach to this group of diseases. Herein, we describe the design, synthesis, and biological evaluation of a series of Cisd2 activators, all thiophene analogs, based on a hit obtained using two-stage screening and prepared via either the Gewald reaction or by intramolecular aldol-type condensation of an N,S-acetal. Metabolic stability studies of the resulting potent Cisd2 activators suggest that thiophenes 4q and 6 are suitable for in vivo studies. The results from studies on 4q-treated and 6-treated Cisd2hKO-het mice, which carry a heterozygous hepatocyte-specific Cisd2 knockout, confirm that (1) there is a correlation between Cisd2 levels and NAFLD and (2) these compounds have the ability to prevent, without detectable toxicity, the development and progression of NAFLD.

The first total synthesis of cytopiloyne, an anti-diabetic, polyacetylenic glucoside.

The first total synthesis of cytopiloyne 1, a novel bioactive polyacetylenic glucoside isolated from the extract of Bidens pilosa, is described. The structure of cytopiloyne was determined to be 2-ß-D-glucopyranosyloxy-1-hydroxytrideca-5,7,9,11-tetrayne by using various spectroscopic methods, but the chirality of the polyyne moiety was unknown. Herein, the convergent synthesis of two diastereomers of cytopiloyne by starting from commercially available 4-(2-hydroxyethyl)-2,2-dimethyl-1,3-diozolane is described. The synthetic sequence involved two key steps: stereoselective glycosylation of the glucosyl trichloroacetimidate with 1-[(4-methoxybenzyl)oxy]hex-5-yn-2-ol to give the desired ß-glycoside and the construction of the glucosyl tetrayne skeleton by using a palladium/silver-catalyzed cross-coupling reaction to form the alkyne-alkyne bond, the first such use of this reaction. Comparison between the observed and published characterization data showed the 2R isomer to be the natural product cytopiloyne.

New, general, and practical preparation of methyl ketones via the direct coupling of amides with CH2Cl2 promoted by TiCl4/Mg.

The direct coupling of a variety of amides with CH2 Cl2 or CD2 Cl2 promoted by TiCl 4/Mg/THF provides an extremely simple, practical, selective, and efficient approach for the construction of methyl ketones. The efficiency and practicability of this chemistry is illustrated by the very simple synthesis of deuterated methyl ketones.

Synthesis and biological evaluation of novel C-indolylxylosides as sodium-dependent glucose co-transporter 2 inhibitors.

Sodium-dependent glucose co-transporter 2 (SGLT2) inhibitors are the current focus on the indication for the management of hyperglycemia in diabetes. Here, a novel series of C-linked indolylxyloside-based inhibitors of SGLT2 has been discovered. Structure-activity relationship studies revealed that substituents at the 7-position of the indole moiety and a p-cyclopropylphenyl group in the distal position were necessary for optimum inhibitory activity. The pharmacokinetic study demonstrates that the most potent compound 1i is metabolically stable with a low clearance in rats. In further efficacy study, 1i is found to significantly lower blood glucose levels of streptozotocin (STZ)-induced diabetic rats.

Discovery of novel N-ß-D-xylosylindole derivatives as sodium-dependent glucose cotransporter 2 (SGLT2) inhibitors for the management of hyperglycemia in diabetes.

A novel series of N-linked ß-D-xylosides were synthesized and evaluated for inhibitory activity against sodium-dependent glucose cotransporter 2 (SGLT2) in a cell-based assay. Of these, the 4-chloro-3-(4-cyclopropylbenzyl)-1-(ß-D-xylopyranosyl)-1H-indole 19m was found to be the most potent inhibitor, with an EC(50) value similar to that of the natural SGLT2 inhibitor phlorizin. Further studies in Sprague-Dawley (SD) rats indicated that 19m significantly increased urine glucose excretion in a dose-dependent manner with oral administration. The antihyperglycemic effect of 19m was also observed in streptozotocin (STZ) induced diabetic SD rats. These results described here are a good starting point for further investigations into N-glycoside SGLT2 inhibitors.

Discovery of non-glycoside sodium-dependent glucose co-transporter 2 (SGLT2) inhibitors by ligand-based virtual screening.

A ligand-based virtual screening strategy (a combination of pharmacophore model generation, shape-based scoring, and structure clustering analysis) was developed to discover novel SGLT2 inhibitors. The best pharmacophore model, generated from eight glycoside inhibitors, was utilized to virtually screen three chemical databases that led to the identification of three non-glycoside SGLT2 inhibitors. This is the first report of the generation of a pharmacophore model from glycosides that has then been used to discover novel non-glycosides hits.

Novel ambiphilic dichlorocarbenoid equivalent in alkene cyclopropanation and carbonyl olefination.

The Ti-Mg-dichloromethylene complexes derived from the oxidative addition of CCl4 to the Mg-TiCl4 bimetallic species serve as a novel class of ambiphilic dichlorocarbenoid equivalents. Not only is Ti-Mg-dichlorocarbenoid highly selective but also it seems highly reactive in both alkene cyclopropanations and carbonyl dichloromethylenations.