
%0 Journal Article
%A Bercich, MD 
%A Cambie, RC 
%A Howe, TA 
%A Rutledge, PS 
%A Thomson, SD 
%A Woodgate, PD 
%T Experiments Directed Towards the Synthesis of Anthracyclinones. XXV. Synthesis of a Vineomycinone B<sub>2</sub> Methyl Ester Intermediate From Anthrarufin
%J Australian Journal of Chemistry
%D 1995/03/01
%V 48
%N 3
%P 531-549
%K 
%R https://doi.org/10.1071/CH9950531
%U https://www.publish.csiro.au/paper/CH9950531 
%X 6-(1'-Formyl)-1,5-dimethoxy-2-(2&#8243;-oxopropyl) anthraquinone (1), a key intermediate in Danishefsky's synthesis of vineomycinone B2 methyl ester (5), has been prepared by a new route from anthrarufin (6) via the intermediate 1-methoxy-2-(2&#8242;-methylprop-2&#8242;-enyl)-5-(2&#8242;-methylprop-2&#8242;-enyloxy) anthraquinone (20). An alternative synthesis of the diketone (40) has been achieved via Claisen rearrangement of (20) and a subsequent ozonolysis of the resulting bis ( methylpropenyl ) anthraquinone (26). Other routes to (1) from anthrarufin have been developed. In one, compound (1) was formed in yields of 10-16% as an anomalous product from the ozonolysis of (27). Ozonolyses of mixtures of (27), (37) and (44), obtained by isomerization of (27), afforded (1) in yields of 28-43%. Isomerization of the diphenol (25) with palladium(II) chloride bis ( acetonitrile ) in refluxing chloroform proceeds at a faster rate than the isomerization of (27), thereby affording the mono isomerized  diphenol (38) in 37% yield. Methylation of (38) affords (37), a known precursor of (1). 
