Natural Product-Derived Chiral Pyrrolidine-2,5-diones, Their Molecular Structures and Conversion to Pharmacologically Important Skeletons.

The versatility of the natural products (2,3)- and (2,3)-3-hydroxy-5-oxotetrahydrofuran-2,3-dicarboxylic acids ( and ), isolated in large amounts from tropical plant sources, has been demonstrated by the construction of 3-substituted and 3,4-disubstituted chiral pyrrolidine-2,5-diones. The absolute configurations of chiral pyrrolidine-2,5-diones have been ascertained using chiroptical spectroscopic methods and/or single-crystal XRD data. A combination of different reaction strategies delivering a diverse matrix of fused heterocyclic ring systems is presented.

Dissymmetry Factor Spectral Analysis Can Provide Useful Diastereomer Discrimination: Chiral Molecular Structure of an Analogue of (-)-Crispine A.

(1,10)-1'-(()-1,2-Dihydroxyethyl)-1-hydroxy-8,9-dimethoxy1,5,6,10-tetrahydropyrrolo [2,1-]isoquinolin-3(2)-one, an analogue of (-)-crispine A, with three stereogenic centers is synthesized and its absolute configuration (AC) established using the combined information derived from the synthetic scheme and single crystal X-ray diffraction data. The experimental chiroptical spectra (namely, optical rotatory dispersion (ORD), electronic circular dichroism (ECD), and vibrational circular dichroism (VCD)) and the corresponding quantum chemical (QC) predicted spectra for all diastereomers are used to evaluate the AC. The AC of the synthesized compound could be correctly established using any one of the three chiroptical spectroscopic methods (ORD, ECD, or VCD) when the relative configuration is constrained to be that derived from X-ray data or when the ACs of two of the chiral centers are constrained to be those derived from the synthetic scheme.