Gábor Günther

Synthesis and stereochemistry of 1,3,2-oxazaphosphorino [4,3-A]isoquinolines

Abstract 1,3,2-Oxazaphosphorino[4,3- a ]isoquinolines 8a,b, 9a,b and 10a were synthesized by the reactions of homocalycotomine 7 with appropriate dichlorophosphorus derivatives, such as phenylphosphonic dichloride, bis(2-chloroethyl)phosphonic dichloride or phosphoryl chloride. In spite of the blocking effect of the connecting isoquinoline ring system, the oxazaphosphorinane moiety exists as a chair–twist equilibrium, where the conformer ratios are strongly dependent on the P-4 configuration and the stereoelectronic properties of the substituents.

Isolation and structure elucidation of four new dihydro-β-agarofuran polyesters from Euonymus sachalinensis

Four new dihydro-β-agarofuran polyesters 1–4 have been isolated from the fruit of Euonymus sachalinensis(Celastraceae) and their structures elucidated by means of 1H and 13C NMR spectroscopy, including 1H–1H COSY, DEPT, 1H–13C COSY and COLOC measurements, mass spectrometry and chemical reactions. The configurations have been determined on the basis of NOESY spectra and X-ray analysis. The isolated compounds are the first native representatives of 3, 12-oxygenated dihydro-β-agarofuran in which the usual macrocycle is missing. The structural similarity of compounds 1–4 and the macrocyclic derivatives is noteworthy from a biogenetic point of view.