An alkoxide-catalyzed directed diboration of alkenyl alcohols is described. This reaction occurs in a stereoselective fashion and is demonstrated with cyclic and acyclic homoallylic and bishomoallylic alcohol substrates. After oxidation, the reaction generates 1,2-diols such that the process represents a method for the stereoselective directed dihydroxylation of alkenes.

The cis- and trans-stereoselective radical additions to α-methylene-γ-alkyl- γ-lactams were investigated and the scope and limitation of the reaction were also revealed. This stereoselective radical reaction was used for synthesis of chiral pyroglutamic acid derivatives starting from a commercially available chiral amino acid.

Stereoselective formation of substituted 1,3-dioxolanes was achieved through an assembly of three components: alkene, carboxylic acid and silyl enol ether. The reaction proceeded via stereospecific generation of a 1,3-dioxolan-2-yl cation intermediate during oxidation of alkene substrates with hypervalent iodine. The stereoselective trapping of the cation intermediate with silyl enol ether comp...

A tetrasaccharide repeating unit corresponding to the cell-wall lipopolysaccharide of E. coli O40 was synthesized by using a convergent block glycosylation strategy. A disaccharide donor was coupled to a disaccharide acceptor by a stereoselective glycosylation. A 2-aminoethyl linker was chosen as the anomeric protecting group at the reducing end of the tetrasaccharide. All glycosylation steps a...

The kinetics of propranolol enantiomers are stereoselective when high doses of the racemic drug are given po. To document whether the dose and/or the route of administration determines the stereoselective kinetics of propranolol enantiomers, conscious rabbits received 40, 80, or 120 mg/kg po or 0.5 or 10 mg/kg iv doses of racemic propranolol, and serial blood samples were obtained to assay prop...

The stereoselective metabolism of lansoprazole enantiomers was evaluated by incubation of human liver microsomes and cDNA-expressed cytochrome p450 (p450) enzymes to understand and predict their stereoselective disposition in humans in vivo. The intrinsic clearances (Clint) of the formation of both hydroxy and sulfone metabolites from S-lansoprazole were 4.9- and 2.4-fold higher than those from...

We report an indium triflate-catalyzed stereoselective intramolecular tandem conjugate addition of secondary amines to α,β-bisenones to afford a 1,2,3-trisubstituted six-membered ring bearing diketone substituents in good to excellent yields at room temperature. Various kinds of α,β-bisenones and amines were employed to expand the scope of this chemistry. Intramolecular trapping of indium-enola...

Monomeric Ti(IV)/C3 trialkanolamine complexes are effective catalysts in the stereoselective sulfoxidation of alkyl aryl sulfides (ee’s up to 84%, 0.1% of catalyst). Such complexes were shown to have a biphilic nature, behaving as electrophilic oxidants towards sulfides while a nucleophilic pathway dominates the oxidation of sulfoxides. The analogous Zr(IV) complexes, likely dimeric, are even b...

(2S,3R)-3-Hydroxy-2-(hydroxymethyl)-3,6-dihydro-2H-pyridine 8, an important precursor for the synthesis of polyhydroxylated piperidine azasugars, has been prepared from L-serine. Highly stereoselective nucleophilic addition to amino aldehyde 5 gave the corresponding allylic alcohol 6 which proceeded to give dihydro-2H-piridine 7a via a Grubbs II catalyzed RCM. Stereoselective H-bond directed ep...

In this study, we aimed to investigate the dysfunction of zebrafish embryos and larvae induced by rac-/(+)-/(-)- PCB91 and rac-/(-)-/(+)- PCB149. UPLC-MS/MS (Ultra-performance liquid chromatography coupled with mass spectrometry) was employed to perform targeted metabolomics analysis, including the quantification of 22 amino acids and the semi-quantitation of 22 other metabolites. Stereoselecti...