
TY  - JOUR
A1  - Rozek, Tomas 
A1  - Janowski, Wit 
A1  - Hevko, John M. 
A1  - Tiekink, Edward R. T. 
A1  - Dua, Suresh 
A1  - Stone, David J. M. 
A1  - Bowie, John H. 
T1  - Syntheses of Angucyclinones Related to Ochromycinone
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1998
VL  - 51
IS  - 6
SP  - 515
EP  - 524
KW  - 
UR  - https://doi.org/10.1071/C97151 
N2  - Two synthetic approaches have been investigated for the syntheses of model angucyclinones related to ochromycinone. The first involves a Diels&#8211;Alder/Friedel&#8211;Crafts strategy in which the Diels&#8211;Alder adduct formed between dimethyl acetylenedicarboxylate and 3-ethenyl-5,5-dimethylcyclohex-2-en-1- one was converted into 6,6-dimethyl-8-oxo-5,6,7,8-tetrahydronaphthalene-1,2-dicarboxylic anhydride, which was then reacted with benzene in a Friedel&#8211;Crafts reaction. Acid-catalysed cyclization of the Friedel&#8211;Crafts products gave 3,3-dimethyl-3,4-dihydrobenz&#91;a&#93;anthracene-1,7,12(2H)-trione (3) in poor yield. Angucyclinones related to (3) are formed (in 40&#8211;50% overall yield) by aromatization of the adduct formed between the appropriate 1,4-naphthoquinone and 3-&#91;(E)-2-methoxyethenyl&#93;- 5,5-dimethylcyclohex-2-en-1-one (this dienone reacts with itself by a Diels&#8211;Alder process to yield an adduct which decomposes to 3,3,8,8-tetramethyl-3,4,7,8-tetrahydroanthracene-1,6(2H,5H)-dione). When the substituted 1,4-naphthoquinone is unsymmetrical, a boron triacetate assisted Diels&#8211;Alder reaction gives a single regioisomer (e.g. X-ray investigations indicate that 8-hydroxy-3,3-dimethyl-3,4-dihydrobenz&#91;a&#93;anthracene-1,7,12(2H)-trione is the product from 5-hydroxy-1,4-naphthoquinone). An X-ray structural study of the Diels&#8211;Alder adduct in the above reaction confirms the operation of an endo cyclization. 
ER  -

