
TY  - JOUR
A1  - Russell, RA 
A1  - Collin, GJ 
A1  - Crane, MP 
A1  - Gee, PS 
A1  - Krauss, AS 
A1  - Warrener, RN 
T1  - Anthracyclines. XI. A short, site-specific synthesis of unsymmetrical 3-Acetyl-5,8-dialkoxy-1,2-dihydronaphthalenes; key precursors to daunomycinone AB-synthons
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1984
VL  - 37
IS  - 8
SP  - 1721
EP  - 1728
KW  - 
UR  - https://doi.org/10.1071/CH9841721 
N2  - 5,8-Dihydronaphthalene-1,4-diol, readily available from benzoquinone and buta-1,3-diene, is isomerized by heating with strong sodium hydroxide, and acetylated (Ac2O), in situ, to form 5,8-diacetoxy-1,2-dihydronaphthalene. Catalysed (AlCl3) addition of acetyl chloride followed by dehydrochlorination (LiCI/HCONMe2) yielded 5,8-diacetoxy-3-acetyl-1,2-dihydronaphthalene (11) in 82% overall yield. Base hydrolysis of (11), followed by methylation (Me2SO4) gives 3-acetyl-5,8-dimethoxy-1,2-dihydronaphthalene in 94% yield, the most direct route to this product so far described. More importantly, the diacetate (11) is selectively deacetylated at C5 (Cs2CO3 in tetrahydrofuran, or K2CO3 in Me2SO) to form the related phenol, alkylation of which produces the 5-alkoxy compound. Further hydrolysis followed by alkylation yields the unsymmetrically, but regiospecifically substituted, 3-acetyl-5,8-dialkoxy-1,2-dihydronaphthalenes. This method is specifically illustrated by the production of 3-acetyl-5-benzyloxy-8-methoxy-1,2-dihydronaphthalene which is formed in a short, cost effective synthesis in a moderate overall yield (25%) based upon benzoquinone as starting material;significantly, no chromatographic separations are required. 
ER  -

