Studies towards the Enantioselective Synthesis of Cryptowolinol via Pd-Catalyzed C(sp)-H Arylation/Parallel Kinetic Resolution.

We report a model study towards the enantioselective synthesis of the dibenzopyrrocoline alkaloid (-)-cryptowolinol. The key step involves a challenging enantioselective Pd-catalyzed C(sp)-H arylation performed with a chiral NHC ligand, which proceeds via parallel kinetic resolution (PKR). A very efficient PKR process was achieved on a deoxygenated model substrate and was successfully transposed to a potential intermediate en route to (-)-cryptowolinol.

Remote Construction of N-Heterocycles via 1,4-Palladium Shift-Mediated Double C-H Activation.

In the past years, Pd -catalyzed C(sp )-H activation provided efficient and step-economical methods to synthesize carbo- and heterocycles via direct C(sp )-C(sp ) bond formation. We report herein that a 1,4-Pd shift allows access to N-heterocycles which are difficult to build via a direct reaction. It is shown that o-bromo-N-methylanilines undergo a 1,4-Pd shift at the N-methyl group, followed by intramolecular trapping by C(sp )-H or C(sp )-H activation at another nitrogen substituent and remote C-C bond formation to generate biologically relevant isoindolines and β-lactams.

C(sp )-H Arylation Promoted by a Heterogeneous Palladium-N-Heterocyclic Carbene Complex in Batch and Continuous Flow.

A heterogeneous reusable palladium(II)-bis(N-heterocyclic carbene) catalyst was prepared and shown to catalyze the intramolecular C(sp )-H activation/cyclization of N-alkyl-2-bromoanilines furnishing indolines. This new catalytic system was based on a bis-imidazolium ligand immobilized on a spaced cross-linked polystyrene support. The iodide ligands on the catalyst played a central role in the efficiency of the process occurring through a "release and catch" mechanism.

Chiral Catalysts for Pd -Catalyzed Enantioselective C-H Activation.

In the past few decades, processes that involve transition-metal catalysis have represented a major part of the synthetic chemist's toolbox. Recently, the interest has shifted from the well-established cross-coupling reactions to C-H bond functionalization, thus making it a current frontier of transition-metal-catalyzed reactions. Constant progress in this field has led to the discovery of enantioselective methods to generate and control various types of stereogenic elements, thereby demonstrating its high value to generate scalemic chiral molecules.

Quantitative analysis of γ-glutamylpeptides by liquid chromatography-mass spectrometry and application for γ-glutamyltransferase assays.

γ-Glutamylpeptides are largely produced via the action of γ-glutamylcysteine synthetase or γ-glutamyltransferase (GGT). GGT transfers the γ-glutamyl moiety from glutathione (GSH) and other γ-glutamyl compounds to amino acids, peptides, or water. A conventional GGT assay employs a synthetic donor substrate, which facilitates monitoring cleavage activity by means of colorimetric analyses but provides no information on the resulting γ-glutamylpeptides.

Improved synthesis of 2,4,6-trialkylpyridines from 1,5-diketoalkanes: the total synthesis of Anibamine.

Many pyridine syntheses have been developed to date. In this study, we focused on pyridine synthesis with 1,5-diketone derivatives and hydroxylamine. Treatment of simple 1,5-diketoalkanes and hydroxylamine in basic or acidic conditions gave aldol adducts without any pyridine compounds.