REACTIONS OF KETENE ACETALS 16. THE REGIOSPECIFIC SYNTHESIS OF PARTIALLY METHYLATED PURPURINS

Article abstract of DOI:10.1016/S0040-4020(01)87530-X

Two novel vinylketene acetals, 1,4-dimethoxy-1,3-bistrimethylsiloxybutadiene and 1,3,4-trimethoxy-1-trimethylsiloxybutadiene have been prepared in view of their eventual application to the synthesis of the antitumor antibiotic bikaverin.Use of the former in the elaboration of anthraquinones has shown that structures proposed for two natural products, purpurin 1-methyl ether and 8-hydroxypurpurin 1-methyl ether are in fact those of anthragallol derivatives.The second diene has afforded confirmation of the nature of xanthorin 5-methyl ether as well as of a degradation product of bostrycin.A substitution pattern claimed for another natural product, 5-hydroxyanthragallol 2,5-dimethyl ether, is also incorrect.