Structure revision of 4-hydroxyaloin: 10-hydroxyaloins a and B as main in vitro-oxidation products of the diastereomeric aloins1.

A reinvestigation of the anthrone derivative 4-hydroxyaloin as main product of the mild IN VITRO-oxidation of aloin has led to the revision of the proposed structure as the aloin-analogous oxanthrone derivative, the new 10-hydroxyaloin, which was prepared from aloin by an improved procedure in ammonia at pH 9. 10-Hydroxyaloin was separated into its C10-diastereomers A and B by analytical and preparative chromatographic methods. Their structures were elucidated by spectroscopic methods (FAB-MS; (1)H/ (13)C-NMR; CD), which show that 10-hydroxyaloin A is the 10 R,1' R compound and that 10-hydroxyaloin B has the 10 S,1' R-configuration.