SYNTHESES, CONSTITUTIONS AND PROPERTIES OF STENTORIN AND ISOSTENTORIN

Stentorin and Isostentorin were synthesized from 2-isopropyl-1,3,6,8-t etrahydroxyanthrone by dimerization and chromatographic separation of the resulting regioisomers. The anthrone was prepared in four steps st arting from easily available properly substituted benzene derivatives; the overall yield of the stentorins was 11%. The constitutions of ste ntorin and isostentorin could be unequivocally assigned from the H-1 N MR spectra of their potassium salts and were found to be in agreement with those derived recently by means of a rational synthesis. The spec troscopic, dissociation, and acid-base properties in ground and excite d states as well as the chiroptical properties of the human serum albu min complexes were investigated and discussed comparing them with resp ective data of hypericin, fringelite D, and the natural Stenter pigmen t.