Metallierte Stickstoff-Derivate der Kohlensäure in der organischen Synthese, XIII. Selektive Mono- und Dialkylierung vonN-[Bis(alkylthio)-methylen]glycin-ethylestern zum Aufbau von kettenverlängerten und α-verzweigten α-Aminosäureestern

Biocatalytic, Stereoselective Deuteration of α-Amino Acids and Methyl Esters

α-²H amino acids are valuable precursors toward labeled pharmaceutical agents and tools for studying biological systems; however, these molecules are costly to purchase and challenging to synthesize in a site- and stereoselective manner. Here, we show that an α-oxo-amine synthase that evolved for saxitoxin biosynthesis, SxtA AONS, is capable of producing a range of α-²H amino acids and esters site- and stereoselectively using D₂O as the deuterium source. Additionally, we demonstrate the utility of this operationally simple reaction on preparative scale in the stereoselective chemoenzymatic synthesis of a deuterated analog of safinamide, a drug used to treat Parkinson's disease.

Synthesis of intervenolin, an antitumor natural quinolone with unusual substituents

Synthesis of intervenolin, a natural quinolone discovered by screening for selective growth inhibitors of cancer cells cocultured with stromal cells over monocultured cells, was achieved. The synthesis utilized a thiocyanate-isothiocyanate rearrangement and Suzuki-Miyaura coupling to furnish the characteristic substituents, the iminodithiocarbonate moiety, and the geranyl side chain, respectively. In vivo studies showed that intervenolin inhibited tumor tissue growth in model mice.

Synthesis of sulfur containing dihydro-pyrrolo derivatives and their biological evaluation as antioxidants

The 1,3-dipolar cycloaddition to N-phenylmaleimide of azomethine ylides, generated in situ from sulfanyl-substituted imines of glycine esters, yields 5H-dihydro-pyrrolo products with syn diastereoselectivity. The syn (major) and anti (minor) products were isolated chromatographically and fully characterized by spectroscopic methods and in two cases also by X-ray analysis. The diastereomeric cycloadducts were tested for their antioxidant activity with good results.

Asymmetric Oxidative Dimerization of the Enolates of N-[Bis(methylthio)methylene]- and N-(Diphenylmethylene)glycine Esters

The oxidative dimerization of glycinates 1 with iodine takes place under kinetic control. The stereochemistry of the resulting 3-aminoaspartate 3 depends on the method used (base/solvent) to generate the corresponding enolate 2. Under suitable conditions, high yields and diastereomeric excesses in favor of the threo derivatives 3-I, which have C(2) symmetry, were obtained. In the presence of 8-phenylmenthol as chiral auxiliary (2S, 3S)-3-aminoaspartic acid 5-I was synthesized.

Diastereoselective Synthesis of alpha,alpha-Disubstituted gamma-Carboxypyroglutamates via Sm(III)-Azomethine Ylide Cycloadditions

Sm(III)-azomethine ylides 2 have been generated from ketones 1. Cycloaddition of ylides 2 with alpha,beta-unsaturated esters 3 through a transition state chelation-controlled by the metal allowed for the asymmetric synthesis of gamma-carboxypyroglutamates having a quaternary alpha-carbon that are potentially useful in the synthesis of neuroprotective agents.